21_BOOKS_ENGINEERING_MACHINES_EnglishTranslation_PartIV

The five books Of the Fourth Part, which the Catholic King Philip the second ordered his Chief Engineer Juanelo to write and demonstrate.

Dedicated to his Catholic Majesty by his majar domo Juan Gomez de Mora.

FoURTH VoLuME The Fourteenth Book deals with boats that go over instead of bridges, to cross rivers; and of other bridges.

Fifteenth Book deals with bridges of wood only.

Sixteen Book deals with timber and stone; when they are cut and how stone is removed; and how morter and gypsum are made, as also bricks of various kinds.

Seventeen Book deals with stones in general, and at what time they should be taken from the quarry; and at what time and season they should be placed in the work; and which break most easily; and which are most durable in the work.

Eithgteenth Book treats of how the piers of stone bridges are to be made in various ways.

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FOURTEENTH BOOK Introduction Book of pontoon bridges Now that the author has examined all the uses of water, he has to deal with water as a barrier. If a river bars the way, instead of providing a route for transport, then the barrier must be crossed. The simplest method would be a ferry, but the author is interested in structures; in tbis case therefore in bridges. The books of the fourth volume form a unit, bound togetber by this common tbeme. And since bridges are buildings, they offer a good excuse to describe all building materials in use. Perhaps the study of bridges was inspired by Alberti (IV.6), from whom tbe distinction between wooden and stone brídges may have been taken, but the treatment here is far more thorough, with a concern for detailed instructions on how to achieve each stage.

Following his own principie he starts wíth the símplest type, a ferry boat attached to a cable. Where the cable would have to be so long as to trail in the water under its own weight, posts might have to be set up, or carried on dínghies to lift it clear. That leads naturally to pontoon brídges. Despite their inconvenience as a barrier to river traffic semi-permanent pontoon bridges still crossed the Vistula and the Danube at this time, and indeed a pontoon bridge was proposed for the Seine at Rouen early in the seventeenth century. Of course, blocking a river might sometirnes be the objective; the Spanish army besieging Antwerp (1585) built a bridge of boats over the Scheldt as much to prevent supplies and reinforcements reaching the city, asto keep contact between the forces on opposite banks.

Temporary pontoon bridges, then and since, have been the stock in trade of military engineers serving armies on the march. Bridges on casks or wineskins are often described in accounts of such campaigns. The Spanish writer on artillery, Diego Ufano, in his Artillería reports various types, including one used in Friesland in 1599 (Ufano, p. 270). As the author points out- and others had noted long beforeit would be possible to prefabrícate bridges like those shown in 210r and later, and take them with the army, to be assembled ata crossing which the command knew they would have to get over. A further distinction is made here between che bridge over casks which will even take artillery, and others which are only for the lighter burden of infantry.

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The book o/ boats used instead o/ brz.dges to cross rivers: and o/ bridges

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ecessity has presented men wíth the spur to look for a solution to the problem of crossing rivers; and they have found one. Por they have met with rivers of excessive width and depth, so that there is no chance of fording them, and building bridges over them would be a matter of very great expense. So it has been necessary to discover sorne method of crossing. And so mobile bridges have been invented; that is, with a boat, which travels along a thick cable or towrope, made fast on both sides of the river. By this invention our problem is solved at small expense, although it is true that there has to be someone permanently available to control and steer this mobile bridge or boat. These boats must be located sornewhere convenient for the crossing, in a place where the water is still, and where the river is of adequate depth and banks firm enough for the boat to pull in and out easily. Boat A is attached by the towrope to the two banks of the river.

[!fol. 204v] There is another invention, a boat very different from the one we have just been talking about. When the river is too wide, the towrope can not be used, not because of the width, since it would always be possible to make a towrope to reach frorn one bank to the other; no, that is not the trouble, it is because the towrope can not be raised high enough, not even if it is tautened, so when it is in the middle of the river, it touches the surface, sometimes it is in the water for more than a hundred paces. So it has been necessary to look for sorne other invention.

It has been done by taking the towropes and doing things the opposite way round to what ís usual, placing them lengthwise in the river. By this device rnen found what they wanted and satisfied their need.

The way it is arranged is as follows: a huge stone is planted in the middle of the ríver, with a piece of chain attached to it, projecting above the leve! of the water, and the towrope attached to the chain. It is prevented frorn entering the water by laying it over sorne little dinghies, which support it on wooden forks, fixed in the dinghies. There are three or four of these, with the rope suspended from thern; [/fol. 205r] they are of very simple construction, and are used for this one purpose only. Four, five or more may be used. The rope must be rnuch longer than the width of the river, so as to go from one bank to the other. They usually [434]

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drive a large wooden post into the middle of the river bed, but when this can not be done because of the depth, then they take a huge weight, which goes to the bottom, with a chain attached to it, as we have said above, long enough to rise about two fathoms above the water. The towrope is then attached to the chain and laid over the dinghies, whereby none of the rope is wasted- for just as much is needed as in the boats which carry it across from one bank to the other.

This is the way of this invention: at A the rope is attached, with the dinghies fastened to the rope fore and aft: which is done for the reason stated, that is, so that the rope will not get wet in the water, and begin to fray. Necessity is solved by this invention, which has this advantage besides, that nobody can cut the rope, nor even make use of it by force, as it is fixed in the middle of the river, and if the boat is shifted a little from the bank, there is no fear of anyone damaging eíther boat or rope. So this invention is much more secure than the other kind.

The rope is attached at A. B B B are the dinghies, C the rope. B the boat. D its shelter: [!fol. 205v] the rope is attached to the boat at G. H is the landing to the boat. (Illustration 277) Thís boat ought to have come before1 the boat which has the dinghies; it was left out through carelessness.

[!fol. 206r] Putting boats in this work was due to their being mobile bridges, made in the opposite way to ordinary bridges of wood or stone, which are fixed in one place, so those who cross them, must go over them. It is quite the contrary with these bridges: they move and those who cross them, do not go, but stand still!

But both serve the same function, although they differ in form and operation. The boats are always under the guidance of ferrymen, who steer and control them. But bridges have no need of guidance2, being of so much greater age. In thís way both types are retained. The inventíon of the boat and dinghies is to be found on the Po in Italy, near Mantua3 .

Not content with the invention of the boats, meo have discovered others, whích are more practica!, although also more expensive. So there is yet another kind of bridge of boats, to cross a river, and it too is mobile, for as the river rises, it ís raised with it, and when the water drops, the bridge goes clown. This bridge has no need of anyone to steer or control it. The boats are laid according as the river is wide or narrow; if it is very wide, many are laid together. Eight, ten or twelve may be used, according to the width of the ríver. After you have taken the width, divide ít up between the boats and the space to be left between them, and see if the timbers can reach across. If they can, they are not doubled up, but if they can not, then beams are taken, [!fol. 206v] and four are laid across each boat, so asto project over the side of the boat as far as possíble, to equal distances, as appears by the beams joined together over the other two on each side of the boat. Once this is 1 'this boat ought to ha ve come befo re' ... further evidence that this text is la ter than the drawings: he means that boat A is actually the most primitive form 2 'bridges have no need of guidance' ... the word «tutor» is used for 'ferryman', a rather unusual term, which allows a pun- bridges are much older, so they are grown up, and have no need of tutors ... ' 'on the Po in Italy, near Mantua' ... a similar ferry is described by the Italian mathematician Baldi, in bis commentary on the pseudo-Arisrotelian 'Mechanical Problems' (Baldi 1621, p. 47), but according to him it was at Guastalla; anyway Mantua is not on che Po, although the road to Mantua did cross the Po near Guastalla, so both may well be referring to the same ferry.

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Iilustration 277

done, other beams are laid across the river, as we have drawn them here. The boats should have their gunwales very high, protected by thick planks, where the beams can be laid firm upon the boats. A is the boat, D the beams, which stand up like ribs. The planks morticed to beams D are held by C. And the deck of the bridge is E. (Illustration 278)

[/fol. 207r] These boats are lashed fast to one another, but have free play.

When loaded carts are crossing, the boats must be kept as far apart as possible, because of the things which the river often carrĂ­es along with it, and also in order that boats can pass under the bridge. Convenient entrances must be made at both ends.

If the bridge is to be made where the river is likely to fati, two piers should be made to prevent the boats being left high and dry. For this reason, care should be [436]

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Illustration 278

taken to set up the bridge in a place convenient for entry and exit, where the water always keeps full, right up to the banks. Then, when the river falls, it does not leave the boats parcly aground. And because the boats would be wasted if they were not in contact with the water, those in between are not very large, although the sĂ­ze of the river must be taken into account when making them.

So then, by this invention a bridge has been constructed which is good for all purposes, to carry pedestrians and carts alike, and for people on horseback. The strength of the bridge lĂ­es in this, that if the boats are kept firm, and held fast properly by their cables or chains, they will be as firm in the middle of the river, as at the sides. These cables or chains should cross over, with the boats on the right fastened on the left, [!fol. 207v] and those on the left fastened on the right: and in that way the bridge will be held firm. It has parapets on both sides. In addition, all the beams which go to make the deck of the bridge should be locked with iron pegs, as illustrated at A and C, and with bolts, (Illustration 279) also illustrated here, at A and B where an iron peg has been put in with a bolt to stop it working out of place. And there are others at C D, and so it goes on stage by stage until the end of the beams. Thus, when the spate comes, the bridge is divided into two parts, which are laid against the bank until the spate is passed, and then they are joined up again, and pegged together as they were before.

Illustration 279

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Volume IV And so a bridge is made by which anything can be crossed, [!foL 208r] and the problem of passing over rivers has been solved. These bridges involve attaching cables to the two banks of the rivers. They should be attached as follows: the cables or chains should be very long, because the straighter they are the more strength they have4 and the more crosswise, the less; as may be seen. (Illustratíon 280) There is a great difference in the tying of the boats with M M; their chains A B, attached at D E, and crossing at C, go sideways, and form an obtuse angle, with the other two acute, as the figure demonstrates. The boats O O, whose chains are F G I K, crossing at H and attached to the boats at I K, [/fol. 208v] form four right angles, which exert much greater force than two obtuse and two acute, and from this it may be understood that the straighter the cable or chain, the more naturally it works; and the more it tends to go sideways, the less force it possesses. We have an example of this in the hand: the straighter a thing is, the more force it exerts. This may be observed by taking a thing which is loaded vertically, to support sorne weight, then it may do so without bending. But take the same thing laterally, it can not be done without letting it bend. This may be seen very plainly under the weight; it is only tO be understood of something which will bend, like a beam.

Illustration 280

There are other kinds of bridges, made in different ways, which are not used for ordinary weights, but only to transport armies rapidly, and for no other purpose. These bridges can be conveyed on carts, and assembled in one day, so that the army can cross rapidly without the enemy noticing. These bridges of which we are speaking are for foot passengers only, and resemble boats more than bridges, in that they are mobile.

Take large planks, one jeme thick, andas long as the timber, and drill them through at the head, [!fol. 209r] in the manner here illustrated, and then join them together to form a chain, in one piece. The planks all overlap, as may be seen in the figure. At the end A, the bridge is anchored, (Illustration 281) as we have said. It is ~ 'the straighter they are, the more strength they have' ... somehow he wants to say that the cables will hold better if the two cables shown cross at ríght angles; but it ís not clear why, or really why he thought so. So often these attempts to explain phenomena by contemporary theory only tend to prove how flawed was the mechanics of the day.

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Illustration 281

built up from pieces so that it can be conveyed on carts as the army marches. Two or three pieces are joined together side by side, and pegged with iron pegs and bolts.

So the bridge is assembled, piece by piece, with no need of boats, just the pieces; and with cables to constrain it, it should be very stable. The first piece is to be specially firmly secured; [!fol. 209v] also a few stakes should be driven in with a mallet, until the river is too deep to do so any more. When the middle of the river has been reached, someone should cross with a cable, to help to constrain the bridge, so that the raging of the water can not move what has already been fixed: and so proceed, stage by stage, until you attain the opposite bank of the river.

Should the army be a large one, two or three of these planks may be laid side by side, which is much wider than a single piece. By this invention captains skilled in the art of war take their armies across mighty rivers, it being understood that one is passing through enemy territory, for the first is made for people on foot.

With this stratagem of making bridges, armies may cross without anyone realising where they are going. The bridge can be assembled without getting wet in the least, as may be appreciated from the figure. In order not to have to lay cables, stakes can be driven in, as illustrated in the bridge R S, to keep the bridge stable and secure, so the water will not exert any force against it, specially when it is loaded with troops, and sinks much deeper. For the water then exerts much greater resistance to the bridge, than it does when it cardes no weight, being then higher out of the water, which thus can exert less force against it. [!fol. 210r] (Illustration 282) This is almost the same invention, except that ít has free play at the iron members; that ís, the hook B has free play in the ring C, and in this way it is assembled.

In that way thís bridge is assembled much more rapidly than the previous one, because the ends are linked to each other, as you can see. lt istrue that you do not have to look for a peg, nor take any account to keep anything else, just M and 0[439)

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Illustration 282

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for all the rest is attached- since the members P Q, are so joined, like A B (which are iron):- all joined together. When the bridge is erected it should be covered with boards, or if no boards are to be found, then bundles of cane- and then cover them over with earth. And so it will be possible to cross the river, in a wonderful way, with the greatest of ease.

There are coundess other kinds of bridge for this same purpose, [!fol. 210v] to convey an army over a river; such as wooden butts or casks. T ake casks and lash them together, and lay them on beams, which are joined together in pairs. Lay the casks in order, drive pointed wooden bars inside the pair which is in the water. Above, lay the boards in order; and then more beams are laid lengthwise, and upon them lay more boards in due order. So a crossing will quickly be made, for while sorne men are assembling the bridge, others are laying whatever might be missing- and so the work is finished at great speed. This kind of bridge can and ought to be assembled entirely on the bank of the river; after assembly take sorne rope and draw it little by little to the opposite bank. (Illustration 283) Illustration 283

[!fol. 211,-] This bridge must be made fast to the bank most securely. A and B are the casks; they lay the deck gradually on the beams F G, putting in those pegs H to hold the casks; and upon them the beams C D. Then it is boarded over, with the planks E; and so they finish making this structure. But before the bridge is built the width should be measured, so as to know how many beams will be needed[440]

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although if beams are not laid undemeath the casks it is not inconvenient, provided the casks are linked by the beams that they carry.

This is a wonderful machine for artillery to cross, and other things- like men on horseback. So there will be an excellent passage. If needed, the casks can be doubled, to make the bridge wider, so the army can cross the faster.

There ís another kind of bridge, which can be made of wineskins- that is a very light machine which an army can carry on the road, as these skins take up little space once they have been deflated. Timber is needed, as with the rest of these bridges- the skins are attached to each other by beams and by straps, after they have been inflated. These wineskins should be laid with the hairy side out [!fol. 211v] so they can be preserved with pitch- for if they be laid with the flesh side out, the hide would spoil- through bcing in the water it would easily rot. This bridge will sustain any weight that may pass over it. Three rows of wineskins are laid, joined together, as sketched here below; they are attached to the beams with straps. A is the wineskin; it has two straps, one is B, the buckle C- the other is D, its buckle E. They may be laid in various ways- it is enough to give the procedurefour rows of them may be laid. They should be placed two varas apart from each other. (Illustration 284) [!fol. 212r] These skins are made into bridges, and different things could be fitted upon them, something handy for carriage, to make less bulk and less bother than any bridge that could be made of two hundred hides. They can be of different Illustratíon 284

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Iltustration 285

sorts- one could be built up of little dinghies with planks, crossing from one to the other, so long as they are thick enough for an army to cross. A bridge could be fitted together in thís way: joining three beams A, and laying three more at a distance, which is e, (Illustratíon 285) and so keep laying them gradually until you reach the other bank. Then lay more beams upon these, at a suitable distanceD D D; and so proceed by stages, i.e. by E E E. The upper ones are fastened to the lower enes in the water, and then lay planks on them until the end is reached. [!fol. 212v] The width of this bridge should be twenty palms or more, according to the size of the army. Countless other things could be invented by men of intelligence. The beams which go lengthwise to the river ought to be made fast most securely; those which go crosswise need to be nailed to the lower ones, A and B and C. The upper ones are to be nailed sideways on, D to E, so that the planks G will be firmer and more secure- although if they are not all nailed it is not a drawback, but one or two must be nailed at íntervals.

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FIFTEENTH BOOK Introduction Book of wooden bridges The opening passage may well have been inspired by Alberti's words on the subject; Palladio introduces his chapters on bridges in similar terms, with similar advice on appropriate sites. All distinguish between wooden and stone bridges, dealing with the wooden ones fust. Ancient evidence was sparse: unlike stone bridges, nothing in wood has survived from Roman times, and Vitruvius says hardly anything about bridges at all. The bridge which the emperor Trajan's army built to cross the Danube is depicted on Trajan's column in the centre of Rome- at a height that makes most of it inaccessible to anyone who wished to study its details. So Caesar's bridge over the Rhine became the main source of information, and Alberti adds little to his citation of Caesar's Commentaries.

Only Palladio can be compared for detail to the account here, and even he says relatively little about the process of construction.

Our author begins as usual with the simplest form, a cantilever bridge which he regards as more basic than beam or arch. The central load is transferred, he suggests, to the corbels by extra weighting. Two post-and-lintel bridges follow, also rather elementary.

For Caesar's bridge he puts forward his own theory; his explanation of the <<fibula», a notoriously knotty problem, may have put in his mind the much more elaborare bracing used in the bridges on [217r-220v], perhaps also inspired by the centring used in the building trade. A brief list of the trees which supplied the timber precedes his truss bridges [223r-225v]. The fust of these bears a definite family resemblance to the first of the three «other inventions» of bridges, by Palladio (Book ID, ch. 8), which follow Palladio's account of the bridge he erected over the Cismone in 1552, while the third bridge [224v] is close to Palladio's third. In the first case the main difference is the additional bracing perpendicular to the diagonal struts; in the second the diagonals here extend from the comers of each section. Did our author know of Palladio? When presenting a bridge of his own contrivance later on (IV, 387-93) he claims that he has not seen the like in the architecture books he has read; and Palladio's name is not among them. Palladio does acknowledge that his master carpenter Picheroni had reported to him that he had seen such bridges in Germany. The texts here differ, while our author appears to understand as well as Palladio the principies of these structures.

Maybe the author had seen wooden truss bridges on his travels, or drawings by Palladio, which were well known sorne time before their publication. Not much can be said with [443]

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any certainty; except that we have an early and exact account of a type of bridge with extended space, designed for sites where wooden piers would not be practical, which also extended the life of the wooden bridge.

Since he had offered detaíls of the iron components such as clamps, he now felt he had to provide information on the larger machines used in bridge building: The Piledriver [225v] is of the basic type which the French called sirnply «engin» and the English a «running-ratn>>.

The Rock Drill [227v] was apparently derived from the boring bars used for cannon by gun-casters of the day. A sounding tool to check depth and the nature of the river bed follow, then the piles themselves, to be shod and capped with iron. Once the nature of the bed is known, looser material can be removed with the aid of a rake, before proceeding to work on a cofferdam in which to build up the pier, modelled on a lock-gate, with rwo suggestions for paíls and scoops, and two water-raising devices to give a dry surface to work in.

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Bridges o/ wood alone

he method to be observed in the making of wooden bridges, which are of the greatest convenience where they are built and set up. They are made like streets: and they serve the same function whether they are of wood or stone, but are very different in their design, both in the material and in the form. The bridge is a principal part of any city or town, so in their construction you should reflect carefully when choosing the place where the bridge is to be built, because it should be done in a site convenient for all when it is in a city- and indeed it ís the same when ít ís in the country, ít should be convenient for all the neighbourhood[/ol. 213r] not in sorne hidden place, nor in a comer, orina ravine. Instead ít ought to be sited in a public place which can be seen from afar, because of all the different accidents that can and do happen every day. Try to build bridges in such a way that they can be completed without excessive cost; they should be stable and durable, and almost perpetual, so far as the material will permit. A site should be chosen for the bridge where it is broad; and in a part of the river where there are shallows, and the water fl.ows gendy; a part of the river where there is a good ground to drive in the posts. If ít should happen that there are no shallows, at least let the river not be too deep; nor should the water have too great a fall, nor have high banks; nor should that part of the river vary its ground, bed or path from its regular course. Neither should there be eddies or the deep pools found in bad rívers; nor should it make any bends or the like there, for they can damage the bridge or the banks. Try to avoíd all tums which the water may make- for many reasons; the banks in such a place may be about to fall in; and to avoíd what the spates or floods [fol. 213v] may bríng clown in the way of branches, trees and trunks and so on, which tend to obstruct the píers of bridges so there can be no passage, because all this rubbish piles up, and helps to check the water so ít can not pass freely.

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This wooden bridge is of no great ingenuity, but it is elegant; for sorne of the beams overlap and enter others, which project outward. To provide for what the beams lack in the rniddle, they load them with earth, so that the weíght supports them. But these things will spoil and even destroy bridges, whether of wood or stone, because with weights like that the arches and píers of wooden brídges will be broken and ruined. (Illustration 286) [fol. 214r] Wooden bridges are much easier to build than stone ones- but both types must be well and securely made[445]

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I/lustration 286

as we have said, wooden bridges should be made with a great quantity of timber, and good mortices and wonderful ties. For the construction you should have ready plenty of timber both thick and thin, plenty of nails, iron rings, ropes, pile shoes for the posts, a wooden ram, boats to be employed in the water, beds to seat the tie-beams and parapet and many other accessories. After a choice of site has been made, take the breadth of the river, to know how long your bridge is to extend, to divide up the span of the bridge- how much there should be between one pier and the next- al! should be done with due order, procedure and measure. The first thing is to have good posts; before putting them in, fix their iron shoes at the bottom- they should be made right, with flanges so they can be nailed on.

Then begin to drive in the posts in due order, {fol. 214v] according to the method that has been determined for the form which it has been agreed the bridge should have. I will now begin to illustrate the exposition, from the simplest to the most intricate that I think should be made. Every wooden bridge ought to have a parapet on both sides. (Illustration 287) The bridge is C: that boarded part of the bridge is the upright pier A. It is to be of wood, at least one and a half palms thick, and driven nine to ten palms into the ground. Beam D is to take the tie-beam B. These do not have to be morticed because they extend no further than the beam, ordinarily. The struts E [fol. 215r] go two on each side, one opposite the other, so asto abut against one another in the centre of beam D . They are to be fixed underneath, with their barriers. The parapet F is to be five palms high. The uprights G have side braces for greater stability: they should also have a brace H which helps to prevent the parapet from falling outward.

1/lustration 287 First kind of bridge

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Illustration 288 In front of the bridge piers, put these cutwaters

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This bridge H is quite different from the other. It bears more ingenuity, and has more timber- although I do think that the first is as safe as the second. But it certainly does have more linkage (Illustration 288) in its piers than the previous one- those struts E, which go underneath are of great value in supporting the three piers ABC, which forro a row. The two beams D {fol. 215v] keep all three tied, with the struts E, which help brace beam F to support the tie-beams G in which the boards H are firmly set. The bridge has parapets on both sides. In these wooden bridges the piers can not be seated without a large ram with which the posts are driven in the river bed- this ram we shall illustrate in the last of these wooden bridges.

The bridge which Julius Caesar built upon the river Rhine 1 he describes in his Commentaries. Many have tried to explain it, but in the end very few that I can see have hit the mark- especially in the 'fíbula', which is very difficult to understand, because sorne would have it that it was a rope with which all was bound together, while others want it to be an iron nail, others that it was a wooden tie. This fíbula I think must be understood to be something like a buckle, to perform almost the same function as a buckle in a belt- which is illustrated here in the middle, according to my meaning. (lllustration 289) {fol. 216r] There must be the two pieces G which are always on top and the other two I go across- they take the beam C- since the one holds it so as not to let it drop clown, while the other does not let it go up either. The two posts D in front of the piers A have great strength, since the more the water pushes post D, the more they force pier A downward- so it is not possible to carry off the piers without first removing the beam D. The two struts facing the current of the water, at the back, are a great help. All the piers should incline somewhat toward each other. Beam C should be very thick, at least two palms. Posts A are to be one and a half palms thick, and the two D the same. They are to be driven in well, and shoes should be 1 'the bridge which Julius Caesar b uilt u pon the river Rhine' ... Alberti cites Caesar's original text, without attempting to explain the difficulties. Caesar's Commentaries (Bk. IV, ch. 17) give the impression that Caesar himself desígned the bridge, no credit beíng allowed to anyone else.

He stresses that he fdt it benearh the dignity of the Roman army to cross over a pontoon bridge.

In reality perhaps he did not understand all the details, and that is why parts of his account of the construction are unclear. At all events, 'many have tried to explaín ít' since, including the emperor Napoleon III, who may have wished to emulare it. As may be seen from standard modern editions, consensus on the 'fíbula' (literally «buckle», as the author says) has not yet been achieved.

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Illustration 289

fixed at the lower ends- because otherwise they will never go in well, for when the post meets something hard, it frays and the more blows it is given the blunter it gets, and so it just does not go in. As for the shoe, the shorter its point the further it will be driven into the ground; and the longer, the less will it be driven in. That is why they collect branches in time of spate or flood, from which they will receive much damage, and even be in danger. [fol. 216v] So I say everything should be the opposite- the further apart the piers of a bridge are, the better- and besides that reason for putting in fewer piers, do so also in arder to make the spans wider- at least fifty palms each- and they could be made sixty or more, according to how much timber you have. (lllustration 290) Illustration 290

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This is the plan of the preceding bridge, A- although in this the struts H H have been put in, which are not used to make it in the form of the plan A D here.

The posts A D are defences for the starlíngs, supportíng the bridge B e E F. In each one there are eight posts forming a point toward the current- that is I K L M. The posts which support the braces G G H H should be strong. They are tied by those wooden components N N at the ends BE; and the other two atO O. And these bind together the whole structure with those wooden starlíngs or cutwaters, [fol. 217r] as a defence against the water, so it does not damage the piers of the bridge. In the form of the bridge there are many things which are not in the plan, so as not to confuse the understanding of anybody who is studying the subjectbecause you would not understand which pieces are which- and seeing the form bare like thís, it is more comprehensible.

The tirnber which is good to use in these works of water, for the piers of bridges. The first is green forest pine; oak when green is better than dry; beech, poplar, holm-oak green, ash, wild olive, alder and all the trees which grow near water- but there are many trees which are good for this, that do not grow near water, nor love water, like the hawthorn, the oak, the holm-oak, the olive, the chestnut- yet they are wonderful for putting in as the piers of bridges, because their timber is very salid and compact. (Illustration 291) Illustration 291

[fol. 217v] This truss for a bridge is almost the same thíng as the one before, save that it has certain extra components, which the other does not- it has the

struts H H, because the two parts F F and e are added to reinforce the whole structure. So I will not trouble to recount all the details, as I have dealt with it at length in the previous bridge. (Illustration 292) The method of building a bridge, where the river may be very broad, and there is no ground to drive in the piers because of the great depth of water, [fol. 218r] and the lack of firmness in the bed. Or perhaps it may have very deep banks where it can not conveniently be built, because there is no suitable passagethen this invention of a bridge should be used. So then, on both sides of the river, make two very large, thick, broad piers, which are to be the half of the bridge.

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Volume IV Illustration 292

When these two walls are raised, it is necessary to have ready some long oak beams. As the wall goes up, they are put in position-like beam E. At a certain distance, because of the great depth and breadth of the river- account must be taken of the breadth, for íf it is very broad, the bridge should be made very high, so the beams will project far enough to extend the necessary width. So, let us suppose the river is two hundred palms wide, and there is no way of putting any pier in the rniddle of it- then sorne device must be used in making the bridge.

That is a difficult thing to do- but in the end there is nothing so dífficult as not to allow human ingenuity to attain its end- even if it is not the sum of perfection.

Returning to our subject- the width of the river has been measured, because the beams have to keep advancing outward- even though they extend one before the other, so asto project a quarter of beam. The first beams which are put in position in the wall should go in at least a third part of its length. (fol. 218v] And the posts G which go in upright are to be morticed to the ones which go outside, E D. The struts C should be morticed somewhat into the projecting straight elements E D F. These struts support the whole weight of the bridge.

The component M should be added in the middle, with its two struts L and the tie-beam K, with strut I, and the two Ns. And so it will be extended as far as may be required- as the beams project, so does the bridge grow longer. And let that be enough- for with the numbers it can be understood.

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Fifteenth Book This bridge is very stable by reason of the wooden components seated in the wall, the highest of which should rise with its point upward, because that is the one which has the most weight on its baclc And as I speak of one, let it be understood of all that are put in position. (Illustration 293) [fol. 219r] This bridge is quite different from the rest- it is a single span or stretch. It is a very good invention, which is needed where there is sorne ravine or valley, because of the great depth. For if it were made broad- I mean what the river takes from one side to the other- the components would have to be very high, because the lower the beams the lower will the bridge be. This bridge can be built quite wide, or long, for all its ingenuity is in that middle section B e e D E E F F- once you know how to fit that, all the rest is easy. Three of those trusses Iltustrati012 293

should be used, that is one in the middle and the other two at the sides. The trusses should be tied to each other by beams, joined well. A will be three or four beams long, or more, morticed to one another; the other pieces, the upright posts G G, are of great value in supporting the tie-beam A. The other members K K and H H do much to support the members L L I I; they keep the whole structure bound together, with its three levels. The bridge should be erected with great dexterity, specially where the members join, for you need to know how to seat them- that is a great part of the support, which the bridge will afford itself, [fol. 219v] because of all those bonds. (lllustration 294) This invention of a bridge keeps part of the style of the previous one, although it does vary quite a lot in the construction, except in the middle-- in the rest of it, it is very different, and tied well, and very safe by reason of the struts I I and K K, which tie and secure the components H H F F G G much better. If it were desired to double the members M, that will be much better still because it will be more stable and safe, because of the members N N N, which give great support. But sorne beams should be placed underneath, to stand firmly in the earth for greater stability at the two sides, O O and PP. [fol. 220r] These two members actas a load one upon the other, and hold all those members which form a point upwards, that is F F G G H H N N. In the building of this bridge-- which it is to be supposed will be done where there are very high banks or among rocks- begin at the two sides with the raising in stone of the two beginnings of an arch- to make the bridge [451]

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Illustration 294

very much wider, and also to secure it, because the further the timber is from earth the better will it be preserved. The bridge could be made much longer still, if the wood is strong and of well cut timber. This truss is quite wonderful, not so much for a bridge as for a centring to turn a stone vault- if you know how to fit ene by keeping the proper curve for a centring or falsework. All the tie-beams should be morticed, as has been said above. That will be a wonderfully stable structure if it is made the way it should be. Here I will not bother to illustrate more of its formit is true that it should have three of those trusses, one in the middle and two at the sides in the same style- in order not to confuse the judgement and the comprehension of anyone who wants to understand a thing like this.

[fol. 220v] (lllustration 295) This invention of a bridge is a very new kind of truss, with piers fixed in the river bed. This invention has those rods, which are Illustration 295

A

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Fifteenth Book great help in two ways; one, that they tie the two piers e D, so that in no way can one alone fail, because of the cross formed by them on each of the two piers e D, and by the rods E E themselves as they are attached in the middle at G ande D. That is obvious- neither of the two can budge, or they must budge together at one stroke: for one cannot budge alone even if the water should eat away all the ground around one of the piers [fol. 221r]. The other reason is because those two m~mbers H 1 project so far forward, and support the beam B. The beams B should be tied at the head- and any beam will do- it will reach from one to the other with a great projection of the beam, so anything can be done, however wide the spans are. lt is a matter of great ingenuity, beside the two members F F which offer much support, in two ways. For those two help to keep the other two E E upright, which is great help toe D. These two are twelve or more palms apart, because the further apart they are the better, provided it is notas muchas the span. They are separated for two reasons; one, that if these posts are driven in too close they move the bed; and the other, that they collect too many branches in between the two of them, and that would cause much water to accumulate there, which could be a source of great damage. The method of the plan will be illustrated later on. Therefore they should be placed somewhat apart so as not to find the bed moved; and so it will stay stable and secure- even if the malicious will not fail to say that the piers are too far apart...

This bridge A with its tie-beams B, its struts E E E E; its piers G G G G support the tie-beams B, and the rods E E and F F [fol. 221v] forma cross on the piers- they both are to be morticed to the piers G with a half dovetail, although the other components are to be inserted, which cuts off the beam. So then it does not have any force. But for anyone who knows how to make it, who will give it much substance of timber, being tied in so many places it is not possible that it should fail with so many mortices. Someone could tell me that those rods go too far clown- but they remain so high that no flood will touch them, and that is enough for they secure the piers by binding them in different places. And so they will have great stability. Either there must be a very great disaster or nothing will be carried away at all because of the ties which hold all the members together. That, I think, is enough on the subject of this bridge.

A1l of them should be made with parapets because of the animals, which can bump into one another and fall in the river. (Illustration 296) [fol. 222r] They have those posts K andO, which form crosses along the whole parapet, and are tied with the uprights, which drop vertically. The piers L go high up, much higher than the parapet; and there is to be a transom, or transoms, M, to hold the two standards or uprights which rise on either side of the parapets. The transoms or bonds R P Q also go on both sides of each parapet; so that rises much higher than the parapets of ordinary bridges. The piers of the bridge, A E G need to be thick and very long, and at the bottom, where they are driven into the ground they should have iron shoes firmly seated. Each pair should have its struts DI T V, and the post H is forward of the bridge piers- it has its strut and makes the piers G firmer. So the more powerfully the river flows, the more it presses the upright piers G toward the bed. The brackets or blocks e e at the side of pier A support the tie-beams P- three of these go the fulllength of the bridge- two at the sides and one in the middle. These are morticed; and at the end of the posts underneath go two central half beams N N [fol. 222v] which support the three tie-beams which go from one end of the bridge to the other. The other two tie-beams R Q go on the [453]

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Illustration 296

parapet on either side- they too go from end to end on each side of the bridge.

This whole structure must be well morticed, and nailed down well with good long nails, specially iron nails and pegs and countless other fastenings which may be needed. The whole bed of the bridge should be nailed to thick planks from one end to the other. In the middle the beams F F should have the three piers A E G, which can not be removed without all three failing together. In this bridge the piers need to be well apart from one another- more than fifty feet- because of the mortices. So very few piers will go toa bridge like this. Take note that the piers should be driven home so they penetrate the ground for ten or twelve palms; and also take note of the floods, how far up their waters reach, so that the posts do not touch the water, for if they did that would cause obvious damage and even make them fall however well tied they might be. [fol. 223r] In matters of this kind the greatest care should be taken. (lllustratz"on 297)

This bridge goes through the air; it is invented for use in a place where the river is very rapid, and also where it bears along with it much wood which tends to encumber the piers of bridges. That is often the reason why they fall, when their piers have been moved. Then the flood comes and carries them away. This kind of bridge should have two thick piers, one on each side, to support it, as its weight is very great. A is the beams which cross underneath the brĂ­dge; [fol. 223v] D the upright columns; B is the iron which crosses beam A. C are the struts along the bridge, and E the crosspieces supporting the uprights D. They perform more work than any other components of the bridge. For the struts tie the whole bridge together: and it is very strong, and safe. This beam is what supports the whole bridge. The iron clamps B pass through these holes.

They should be very tough because they have to sustain a great weight, and should be fastened with nails also very tough; and underneath iron pegs should be inserted, to go through the clamp, and hold it firm. (Illustration 298) This is iron clamp B, passing through holes G in beam A. This iron peg H passes through clamp B, although it should be somewhat curved or twisted, so that it will go in with more force, and make it more secure. (Illustration 299) [454]

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Illustration 297 D

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[fol. 224r] Although I may set clown sorne more of these inventions, the same iron components can be used for all of them, or they can be varied slightly, as may · be seen at I. Il/ustration 298

(Illustration 300) The iron B clamp fastened by the peg I, whlch looks somewhat like the volute of an Ionic capital, ís much easier to make, and also safer and stronger because there is nothíng to make it lose its force. It is also better because it constrains the beam A more effectively than peg H. So as these íron parts have to carry the whole weíght of the bridge ít is better to make them too thick than too thin; better lose by giving them too much strength than 11/ustration 299 by keeping them too thin. (Illustration 301) [fol. 224v]

o. .,. ~. ~~~~~,.~. ~

This invention works on almost the same lines as the previous one, although in detall it is quite different, and is much stronger than the first. lt is constructed in the same way, but has those struts at the two ends, which are of the greatest assistance in lightening the load on the iron clamps and the rest; but the two piers must be very strong, as they have [455]

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Volurne IV to carry the whole load, and so must be very thick and broad, and stand on good foundations. (lllustration 302)

Illustration 300

A{lhl~

This invention of a bridge has no pier in the Tlllll water, [fol. 225r] and may be used where the U _p¡ river is very rapid, and so furious that no pier 1 could hold, because of the wood and branches that the water brings clown. Another is the variation in the bed, and therefore also in any foundation of the piers, for if timber píers should get wet, and then be left dry for a while, and the sun should reach them, they would rot and so perish.

Illustration 301 This imaginary design of a wooden bridge

That is why piers may not be used here, and it is necessary to rely on the two piers alone. Even where the river is quite broad, and three to fi.ve of these bridges have to be erected, it can be done with these timber arches with crossing rods and the pillars which support them, although there will also have to be iron fastenings, which are to be made of the same type and in the same positions as illustrated. This kind of bridge is stronger than any I have shown, although indeed many other variations could have been added. But the main thing was to point out how the security of the bridge depends on the construction of the end-piers, and on their stability-. lllustration 302 From one pier to the other there is a span of one hundred and twenty feer.

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[fol. 225v] Now I shall describe the method of makíng stone bridges, according to the procedure usually followed in that kínd of construction, stating what has to be observed in the work, as it will appear in our discussion of the subject what general and particular rules have to be kept and respected as essential precepts in building bridges of various types, laid clown in the previous chapter.

All those who make bridges normally use a very large instrument called a·ram2 , in order to drive the piles into the bed of the river. This ram is lifted up by means of a windlass and its mechanism, but drops of itself, and gives a very sharp blow.

But it is very heavy, and hard to carry about from one place to another because of its weight and the big job of conveying it. Besides, there is a considerable pause between blows, on account of having to raise the ram each time, by drawing clown the cord, although indeed it is quite easy to cure this problem by attaching a cord to hooks which raise the ram; and then allows it to descend.

So I find great disadvantages in having to make use of this machine. That was the reason for seeking sorne other invention that would be easier; more convenient for moving around, and for giving more frequent blows, and driving in the piles more easily and also more rapidly. [fol. 226r] Although it is a ram, yet it is different from the large one, especially in its movement up and clown.

The ram which follows is A. It has these four lugs D D. They are a palm wide, projecting outside the legs e e, undemeath which are the two shoes H H. Pegs are driven into the side to provide a stepladder, to reach the ram when it has to change are crossed at the top by the transom E, which holds position. The two legs them together. However they can be made narrower or wider at the lower end, when need be. And in the middle of the transom E are fixed two pulleys through which pass the ropes B; these same have loops at the end to raise and lower the ram. Six or eight men take hold of each loop, and all pull or release simultaneously, although indeed they must never let the loops slip out of their hands, .but only relax their grip to lower the ram.

ee

(!llustratz'on 303) [fol. 226v] The square shores I I are adjustable; they are used when the ram becomes twisted and keeps hitting the post- that is the reason why they are movable. So the ram strikes them, and they keep it straight. They are nailed to another piece of timber. But when they are driving in piles, each leg is held steady by two men, and the same is done with the leg K, which is not attached to anything but just has a man to hold it fum, and to stop it sliding. It also serves to direct the ram when it has to be pushed forward or pulled back. And with this invention, the pile is driven in much quicker, because it is up in an instant, and clown again the same, and so the blows are much more frequent. And when the machine is moved from one place to another, (Illustration 304) [fol. 227r] the rope never works loose, nor do the pulleys fall out, because sorne carry the machine and by others the ram, at the same time. The shores I I K are attached to the legs iron pegs which also fasten the said legs of the machine.

ee

2 'a very large instrwnent called a ram' ... the larger pile-driver mentioned, with its windlass and quick release mechanism, must have been what the French documents called a 'hye'. Boyer (1984, 1985) has discussed the reasons why it was less often used than the simpler 'engin', which is depicted and described here. In addition our author claims that being lighter this device is more anoeuvrable, and quicker in operation than the other, even if it needs more manpower to work it. A model very similar to this was employed by the Spanish at Antwerp in the erection of a post and lintel bridge, in 1585, according toa plan reproduced by Boyer (Boyer 1984, fig. 2). The hitch over the running nooses here (226v) may be intended to permit a relaxation of grip without letting go altogether.

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Illustration 303 F

Thís ís the way the rope wíth íts loops is placed in the ram; it is set inside the wood, the two ends passing through the pulleys opposite one another, as the figure demonstrates. lt then goes through the lower part of the ram, and as it comes it is bent round, wíth an iron band, and in the upper part there are two iron fastenings which keep ít clown. These are to be no thicker than the lugs D, in order not to rub as they go up and clown. on the legs

ee

The ram is made of holm-oak. The four lugs D do not pass right through it, but are inserted into it to a depth of four fingers only, and are fastened to it by a wooden peg. When the rope wíth the loops is very long, additionalloops are made, wíth a rod through the middle, so that it can be untied the more quickly, to shorten or lengthen ít as the situation may require.

[fol. 227v] During the construction of timber or stone bridges, it will often . happen that a rock is found in the bed of the river, such that no wood pile can be driven in. So when the piers of the bridge are to be erected this obstacle will make it impossible. In this case, the ram is of no use, and we have to look for another [458]

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I/lustration 304 Noose to shorten the rope

solution, a dífferent engine for placíng the piles. To this end I have imagíned another ínvention3 , rememberíng that those who cast artillery, after the castíng is done, bore it out with a well hardened iron drill, in order to remove the rough edges left in the metal and to make the cannon quite clean ínsíde. Remembering that metal is a very hard material, and yet the interior ís cleaned out with this instrument, in the same way the rock could be drilled by an engíne, to make boles in ít, where the timber piles could go. Thus it will be necessary to make an ' 'to this end I have imagined another invenrion' ... large drills were occasionally in use in Italy at this time to bore for wells (Scamozzi, L'Idea dell'Architettura Universale, pp. 336, 346), Besson's book of machines indudes a three-pronged crowbar, otherwise similar to this, which is to push rocks out of the way rather than bore through rock hindering the construction of bridges or jetries.

However the author here makes it dear that his inspiration was the boring bar used in the manufacture of cannon. An attractive drawing of just such a device appears in the 1603 manuscript «Encyclopaedia de Fundición de Artillería>> of Diego de Prado y Tovar, powered by a horizontal waterwheel. But this passage seems to be the only place where it is suggested that such a drill could serve to drive holes for piles.

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Illustration 305

instrument that will serve as a drill, although not of the same construction. It is to be as wide as the piles will be thick, and if the piles should chance to be thicker than the drill, they should be planed, so as not to be too thick, nor yet too thin. The drill is to be like an auger, very thick and also very heavy, weighing at least two hundred pounds of iron.

It is to be shaped like a ploughshare, and have a tail or haft si.x palms long. [fol. 228r] The bit of the drill should be square, with four corners, and steeled along both edges of the blade. The drill itself is to be inserted into a round wooden shaft. But the shaft should not be thicker than the drill. The shape or form of the drill is as follows, with those two points; and it has a slight turn at the side; and there has to be a cutting edge as in drills. (lllustration 305) The shaft of the drill should be morticed into a long pole, and after it is in position, a piece of wood must be inserted to fill the empty space, and also two iron bands, fastened securely. In the upper part of the pole, sorne few boles must be driven, so that it can be rotated r with a bar when it is required to work. The rock should be pierced to the depth of eight or nine palms, to enable the pile to have the c. strength to function as the base of the bridge. [fol. 228v] A hole will be drilled in three or four hours if it is sandstone; if it be sorne other types of stone, then it will take more or less according to the hardness of the stone. The pile can be left somewhat thicker four or five palms up, and then given a few blows with the ram, provided there is not too much extra thickness. This invention can also be used for stone bridges, to put in timber piles to divert the water, so as to lay the foundations for the piers; that is, the cofferdams or defences usually erected for this purpose. For anyone can employ these suggestions or inventions in his works, as he can invent other things because of them; and these may be of better quality, here as in various other branches of architecture. When this drill is required to operate, it involves no more subclety than the weight of the drill itself, which makes it fall, and also helps it to bore faster. Only attention must be paid to the placing of the drill in the same frame, and likewise in noting how far the drill has pierced, how far it has gone into the rock. This may be recognised from the hales in the pole, at E, when the depth will have been reached which the operator intended to go into the rock, although it should not be less than eight palms, nor yet more than ten- because all the rest would be superfluous, and in a very litcle he would be boring into the earth.

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Illustration 306

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Although tlús subject has been cliscussed elsewhere, there is always something to add in questions of ingenuity and imagination. [fol. 229r] So whenever the foundation of any edifice has to be laid in a river, especially piles for a bridge, before anything else one precaution should be taken, that is first of all test the depth of the water with an instrument4. And with this same instrument, test what ground there is, if there be much sand or gravel or stones in that place. To see this, a very long sharp thin iron tool should be made, with a sharp point, made in such a way as it is let down that you have a long spear, and near the point something which penetrates the sand, mud or stone, and when drawn up again; brings up with it something of the ground, and tlús instrument is A. allustration 306) Illustration 307

Illustration 308

After the depth has been observed, a good quantity of sawn J timber should be made ready, for that is the basis of the work; and that means thick planks, quarter beams, whole beams, plenty of nails, bolts, and the iron parts for the planks and for the piles to be driven into the ground. These iron caps for the timber parts should be of the construction here, B. (Illustration 307) They are to be wide in the lower part, where the wooden post is to be fixed. It should have this shape so that when the pile is struck it will not wear at the point like tow. [fol. 229v] For as it wears, the blow of the ram is no longer given firmly, and the pile is not driven in properly. But when shoes of this shape are used, the piles do not bend at the point, and are driven borne better, since they receive the impact squarely, and not wandering about all over the place.

At the top of the piles, there should be a thick band, narrow above and wider below, and fitted to the pile in such a way that the impact of the ram should fall on the iron band only, and not on the wooden pile. If this is done, the piles will be firmer and will not buckle. The ring or band for this purpose should be of the shape C. (lllustration 308) When it is required to erecta pier, a cofferdam should be made~. After taking sueh care as may be necessary, begin to drive it in at the front, or rather, first drive it in at the point, and then at the sides. Before proceeding, clear out all the gravel, sand or stones there may be.

This is done with an instrument, not for lifting 4 'first of all test the depth of the water wíth an instrument' ... sounding at sea was carried out with plumb and line; in shallow water this lance can be used; as at sea, it is hoped to check also the nature of the bed. ' 'when it is required to erect a pier, a cofferdam should be made' ... the author apparently prefers the Italian term 'cataratta', even if he knows the Spanish word as well as French. After sorne advice on shoeing and capping the piles, and a note on the scraper, he deals with the actual cofferdam itself.

The structure is curiously reminiscent of the leaves of lock-gates (and this was the original meaning of 'cataratta'), rather than the dovetailed sheeting of Ramelli (111, 112). Vitruvius' instructions on making cofferdams refer to moles and harbour walls. The practice had been revived in the later Middle Ages (Boyer 1981). Water was usually removed by scoops or pails, as shown here, but as Vitruvius suggests these more complex devices, the author echoes him with the final illustrations of a tympanum wheel and a 'water-bellows', a strange predecessor of suction-pumps. Weird as it looks, this device probably did exist, and appears in a number of Renaissance drawings.

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the material out of the water, but to keep it in motion so that the water will remove it, before the cofferdam is closed.

[fol. 230r] Care should be taken when driving in the piles, to place them in precise order; the three forward piles having to be particularly firm, as they sustain the whole weight of the water.

Then the gravel is removed6 with the instrument D, below. (Illustration 309) It is drawn along with a capstan or winch, which greatly increases the force. It should have along the lower face sorne iron teeth, somewhat curved, but not too much, so as to go more easily through gravel, pebbles, sand, or mud.

Then an instrument must be used, which is called a scraper. It holds in measure two fanegas. This scraper is the instrument employed for cutting out earth from one place and carrying it to another, and is mainly used by farmers for levelling their fields. By this means the place for the foundation can be cleaned out, but the instrument will be described where we treat of dredging harbours. The next step is to finish the closing of the cofferdam, and to bind the members with thinner timber crosspíeces, [fol. 230v] to make the whole secure and fast. Then two rows of planks are driven in round the cofferdam, the inner rank being capped with iron where it is to be driven into the ground, in the manner illustrated below, E . The iron shoe is F. The planks should be caulked on the sides only. (Illustratt'on 310) For the rest, Illustration 31 O

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leave them as they come from the saw. Care should be taken to mark the planks, to know which one goes next to which, as they fit into one another, and are laid clown in due succession. They are to be two fingers thick, or more, in order not to buckle under the weight of earth pressing against the outer planks. Material and labour can be saved by not using the iron shoes on the water side, where they are unnecessary.

But care should be taken in placing the planks to tie the cofferdam at top and bottom, in the manner depicted below. The planks may be cut in a different way, with a half point as the figure illustrates at M, which is more ingenious than the full point. When the space between the planks is being filled with earth, that earth should be fatty, and you must keep on tamping it clown, [fol. 231r] like a mud wall, so that it will get denser and more compact. This is done with a beetle or stamp, H.

(Illustration 311) The cofferdam is N. The French call it bastardel, but in these kingdoms of Spain it is called encajonado. This machine needs great vigilance in erecting it, 6

'then the gravel is removed' ... Thomas Platter noted a rake, perhaps like the one depicted, dredging the harbour of Lattes in Languedoc in 1595 (Jennert 1963, p. 55), and he remembered seeing something like it in a book of machines, possibly Besson's huge dredging rake (Besson 21).

This implement is altogether more modest, intended only to loosen the bed so that the river's own cunent will bear it away. The second stage scraper appears at V 445v, as promised.

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1/lustration 311

and firm support. After the cofferdam has beeo completed, it will be necessary to pump out the water from inside. This may be done with various instruments, and note should be taken of the quantity involved in order to know which is needed. For if there is a considerable depth of water, then instruments like the screw [fol. 231v] or Ctesibius' force-pump with pipes should be used. But if the water is not very deep, then a scoop can be employed, of the shape and construction of P, and provided that the cofferdam is quite shallow it will dear a great quantity of water. Much may be done with a bucket Q, lifted by two men, although if the water is deep, it would be worth harnessing one or more horses, and putting up a scaffolding or platform for them, as the job would be done more easily, at less expense and with less labour, because two beasts will do more than eight men. And this advice should be borne in mind by anyone who undertakes work of such a kind. (Illustration 312) Illustration 312

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With these implements then, water can be drawn from a cofferdam, but if the depth is too great, the instruments mentioned above, or something similar, will have to be used. {fol. 232r] Although many more details could be set clown here, they may be left to the discretion of the builder, who will know how to solve his problem with good judgement. lt is enough to have given the main procedure to be followed in the constructĂ­on, for it would be impossible to offer solutions and advice on everything that can happen in these works, because the situations differ, and so do the effects of the river's own flow. Grounds differ and currents vary, and materials are different in every province, and therefore I can not give advice about everything. As if we should say that they can only be constructed of cut stone, and lt could happen that you have to build in a region where there is no stone, but that is no reason to give up, for if there is no stone, there may be bricks; and on the contrary if it should be said that only brick might be used, and in a certaln place there was no supply, that would be no reason not to build.

Illustration 313

In cleaning the grave! of the bed, the instrument should be attached to a rope, and drawn along by a winch, and then moved back by another rope.

So the grave] will be disturbed and gradually cleared, and then the sand, until a firm base is reached, in which foundations can be laid.

A tympanum-wheel can also be employed. lt is enclosed all round, with radial sections like a wheel, and has two bases covering these sections. The water is discharged next to the axle. {fol. 232v] Next to the circumference there is a hole where the water enters.

Two men turn the wheel, once it is erected in a position where it can rotate properly.

And there should be holes at top and bottom, with two in each section, one for inlet and one for outlet. The construction of the wheel is as follows: (although this'wheel has only six sections, it can be made with a larger number, depending on the size. But there must not be less than six). The water enters atA, and leaves at B. The instrument is to be placed on a stand when in use, but even so the water is not raised very hlgh with this wheel. (Illustratt'on 313) For the same purpose, the instrument of the bellows may be used. It has the same construction as the ones used by blacksmiths, with not one detail missing. {fol. 233r] lt lifts a considerable quantity of water, and can be driven in various ways; and specially by the very water of the river. Then let two such bellows be installed, at least seven or eight foot in length, since the instrument performs its function better the bigger it is. The wheel, moved by the water, is K, and turns on the axle L. The blades are l. The bellows are driven off the cam H. allustratt'on 314) The bellows-board is raised at D, and so the boards are kept alternately in motion.

In the pipe E there are holes at F through which the water may enter, and at G there is a leather valve on a metal plate. This latter should be pierced, and fĂ­xed securely. There should be another valve in the bellows-board itself, where the pipe is attached to it, atE. {fol. 233v] The metal plates are employed because otherwise [464]

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Fifteenth Book when the leather gets wet, it will hang loase, and cease to be effective. The valves are to be fastened on one side only, so that they can lift open when the bellows attract the water, and clase during the discharge, to stop the water returning whence it carne. Countless instruments can be installed for this work, from among those that have been discussed elsewhere, when I dealt with stone bridges.

Illustration 314

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SIXTEENTH BOOK Introduction Book of Trees and Timber Until very recent times, wood was the main material for an enormous variety of tools, furniture, ships and vehides; for fue! and even for food in the form of fruít. Almost everywhere therefore, the timber trade was a vigorous and profitable branch of the economy. Naturally wood was used for most of the artefacts described in these books, and ít is hardly surprising that one 'libro' should be devoted to trees and timber.

Despite the long sub-títle, other construction materials are not tackled until the next book. In the circumstances it is disappointing that so little of the information here originares with our author. He is heavily dependent on Alberti (II 4-7), but could perhaps justify himself by pointing out how much Alberti drew from Greco-Reman sources, above all from the obvious Vitruvius who had devoted two chapters of his book on materials to wood; and the encyclopaedic Pliny. Alberti stresses that Ancient authors will be more knowledgeable than contemporary experience: read what the wise men of old have to say, rather than modern workmen. He did use more recondite works, in particular the agricultura! writers, Cato, Varro and Columella. Sometimes he did go right back to Theophrastus, fountainhead of Ancient, and Renaissance botany.

Every one of the Ancient authorities named here comes from Alberti, and every place and curious event too. These references have al1 been identified by Portoghesi. If the text seems to ramble it is because these excerpts are not well organised, and Bartoli had introduced fresh errors and misnomers. So unfortunately this book is not much use as a guide to methods and choices exercised in sixteenth century Spain. Apart from odd comments, the most original passage is the panegyric in praise of wood [246v-247r], very much in Renaissance taste; and the account of floating timber clown rivers which follows.

The 'libro' is divided into topics:

Felling [233v-236r]- the time and the techniques- most of it folklore of great antiquity.

Only the final paragraph on cutting down trees in January seems to be the author's own comment, perhaps based on the practice of the ordinary woodsmen, portrayed in the charming vignette [236r]- one of whom has evidently stopped for a quick swig.. .

Then [236v] later he notes- perhaps a little exasperated- that «actually trees are felled [467]

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at all times of the year without bothering if ... the moon is waning or waxing>>. Seasoning and Preservation [236v-239r]. This includes a long list of trees, very much longer than Alberti's, for the names from savin onward do not appear in the older list (II.6), although Alberti does refer to sorne in passing later. Identification is often uncertain, beca use Vitruvius and Alberti may not have been referring to the same tree by the one name. Information which has passed through so many changes of language and economy is likely to be unreliable. In particular, the many species of oaks, their numerous varieties and hybridisations, do make for vagueness. Our author adds near the end his own recomrnendation for almond and apple, with surprise; but the reader may be surprised that he took so much on trust from another man's reading.

Uses o/ di/ferent trees, whether for construction or furn.iture [239v-243v]- still very dependent on Alberti. H e adds comments on fir, almond, apple wood. The passage does suggest the immense versatility of wood, but without telling us much about contemporary Spanish carpentry. Otherwise the summary [244r-246r] tells us little more.

The book then ends with an enthusiastic passage on the value of trees and wood, and a discussion, illustrated by a sketch, on the potencial of Aragonese rivers for floating timber downstream.

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On tz"mber and stones) and how they are cut and hewn) and how lime plaster and different kinds o/ bricks are made

N

ow that we have cliscussed wooden bridges, we should deal with those trees which are suitable, and in what season they should be felled.

Theophrastus says1 that this should be done, especially the fir, pitch-tree and pine, when they begin to throw off certain things like grubs, and this because of the excessive moisture, which makes it much easier to take off the bark. It is true that there are sorne other trees, like maple, elm, ash and linden, which must be cut at the time of vintage, or in mid autumn. That is the best season; íf oak is cut in winter, it is very tough, and if in summer, it rots of ítself, and that ís for certain. [!fol. 234r] But if cut in winter they will not split. And pay attenúon to the advice the philosophers have left us, that wood cut when the wind is blowing from the north will rot very easily, although it be green, and although the felling is done in winter. If burnt they give off very little smoke, and from this we may deduce that they are very sappy, and of a certain fatness. This moisture is neither crude nor digested. Vitruvius says2 that timber should be felled in autumn, until the west wind blows. Isidore says that when the sun shines at its greatest strength upon us, and gives a colour like bronze to the countenances of men who go to the fíelds, that is the season for the harvest, but not for cutting clown trees. They must be cut when the leaves begin to fall, that is the season for timber for building. As for timber used for firewood, any season is good enough. Cato, who ís more drcumspect in these matters, wants oak to be cut in high summer, for cutting it in winter is out of season. Trees which have seeds must not be cut until their fruit is ripe: but trees without fruit may be cut whenever we please.

[!fol. 234v] Cut those which have their fruit ripe and green at once, when the fruit falls. The elm must be cut when the leaves fall. lt is further saíd that ít is very irnportant to know the right phase of the moon for cutting úrnber, because the philosophers, specially Varro3 , say that the moon has such power over all touching 'Theophrastus says' ... Historia Phyteon V.l.l. But the real meaning is the new shoots, nothing ro do with worms.

2 'Vitruvius says' ... TI.9.1. 'Cato, who is more circumspect' ... De Agricultura XVTI.l.

'Isidore says' ... acn1ally Hesiod, (Works and Days 383, 405); the mistake is Bartoli's. > 'the philosophers, specially Varro' ... De Re Rustica 1.37.2.

'Columella says' ... De Re Rustica XI.2.11 . 'but Vegetíus thinks' ... Epítome Reí Militarís IV.35. 'but Pliny says' ... HN XVI.l90.

1

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with iron implements, that even those who cut their hair at full moon, afterwards go bald. For this reason alllearned men agree that trees should be felled when the moon is on the wane, and for this they give a good explanation; that then their fatty phlegm dries up. Certainly it is very easy to cause them to decay. So cut under a waning moon, but not of course if the wood is worm-eaten or gnawed. Columella says that timber should be felled from the twentieth to the thirtieth day of the old moon. But Vegetius thinks it should be done from the fifteenth to the twenty second day. From this the ancients took the custom of celebrating those days, as they signify eternity, and wood cut on them lasts a long time. They further say that attention should be paid to the setting of the moon, but Pliny says that he thinks it best to cut trees when the Dog-star begins to appear, and when the moon is in conjunction with the sun, on the day called 'interlunium': [!fol. 235r] and it would be well to wait through that night until the moon has gone clown. The astrologers say the reason given for this is that the moon is the cause of the vigour of the moisture, in the direction of the moon. So all the .moisture then is in the root of the tree, and the rest is left dry and purified. They add that it should be cut all round first, and then, cut at that season, all timber will be very durable. But it should not be cut right through immediately, stillless thrown to the ground to dry out, but left standing over the roots. They say further that if the tree is not as firm as it ought to be because of its excessive moisture, in order to stand up against storms, the felling should be left to the waning of the moon. This remedy is partly used to prevent decay because of water. Sorne consider it certain that if oak, which is of itself the heaviest of trees, and when placed in the water goes straight to the bottom, should be chopped round, and then left until the leaves fall, it will be so changed that if thrown into water, it will float for three months. But others express the opposite opinion, saying that trees should be left in this manner, [!fol. 235v] upright on their trunks or roots, and cut round until you reach the centre of the tree, to drain it.

They add that trees used for sawing and for boards should not be felled until the fruit be ripe, with the seeds, and that the bark should then be removed because it ·causes them to spoil much more easily than they would without it.

Timber should always be cut clown in January because the waning of the moon is drier than in any other month of the year, and so the trees have least moisture, as their pores are more tightly closed, and their wood more solid and compact. But trees which do not shed leaves in J anuary should be cut when the moon is waxing, also because they are drier and less moist. There is this difference between trees which require felling under a waning moon, and those which require it under a waxing one; [!fol. 236r] the reason being that the trees which lose their leaves are much more porous than those which do not, and so, much moister. Someone might ask me how it is po~sible to keep this rule with all the trees that are felled. I can only say that it should be kept, and that the majority of those who are employed in this trade do keep it in each month, all the more so when timber is cut in the winter, and specially if the wood is to be used for buildings. (Illustration 315)

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Illustration 315

On the methods to be used /or preserving wood a/ter z't has been cut Sínce we have dealt with the manner of cutting it, [!fol. 236v] for various purposes specially for constructíng the bridges here ínvented, it would not be off the subject to deal with the types of wood and the nature of trees; which wiJl be good ín the water, and which not, which last more ín the ground and ín foundations, which are good for covered buildíngs, and which are better preserved in one place than another.

Holm oak, Oak, Turkey-oak, D urmast oak, White Poplar, Elm, Píne, Larch, Box, Cedar, Yew, Willow, Alder, Ash, Cypress, Olive and Wild Olive, Chestnut, Savín, Juniper, Cork, Mulberry, Maple, Black Poplar, Walnut, Sorb, Hawthorn, Cherry, Beech, Fir. Of these trees sorne are better than others for different purposes, just as they possess ín themselves different natures and properties. The method of cuttíng clown trees ín forests is too commonplace for discussion, all the more as I have already dealt with the subject.

Actually trees are felled at all times of the year, without bothering if it is better to do so when the moon is waníng or waxing.

Cato is not of the opinion\ índeed wiJl not admit at all that trees should only be felled under a waning moon: he says that they should be cut ín the afternoon, with the sun. [!fol. 237r] After they are cut clown, he ínsists that they should not be transported or dragged through frost or through dew, because that makes them very rough and brittle, and so they easily break. Therefore he says that after felling they must not be touched for three months, nor lie anywhere that is much heated ~'Cato is not of the opinion' ... De Agricultura XXXI.2.

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Volume IV by the sun, since it is very harmful for green timber. Nor should they be laid where strong winds could affect them. For this reason sorne timber is plastered with cow-dung, to preserve it from splitting.

Theophrastus tells5 us to take these precautions; the reason is that giving the timber a covering of this kind closes all the pores of the wood so that there is no place where the phlegm in the tree may exude. On account of the vapours it keeps distilling little by little at the heart, and that causes the whole tree to condense equally throughout, as the wood dries.

There are those who claim that if a tree is placed upside clown, that is with the trunk on top and the branches below, it will dry much more effectively, because the moisture descends by nature; that is, when the tree is standing, the moisture ascends through it.

[/fol. 23 7v] In addition, the philosophers give various recipes for preserving wood from decay and damage. Theophrastus says that burying timber will preserve it. This is done because it thus becomes much more solid. Cato says6 that timber after felling should be greased with dregs of olive oil, or with juniper oil, or with pitch, because that remedy would prevent it being worm-eaten, and stop grubs from causing it damage. lt is well known that wood is harmed and spoilt by water, and the cure for this is pitch and sulphur, mixed together and smeared on. The ancient architects add that wood which is coated with lees of olive oil, of pitch, or of sorne other greasy or fatty substance, catches fue as soon as it is ignited, without making any smoke.

Pliny writes that in a labyrinth in Egypt1 there were many beams of Egyptian white pine, which were plastered with a material of olive oil. Theophrastus writes that wood which is plastered with asbestos will not burn, because asbestos has just this property. l t is a stone, also called amiathus, bostrichites polia or corsois, Caristian flax, Gufeline flax, or esparto palia. [/fol. 238r] lt is ground and placed in sorne material that will stick to wood, and so keeps it from burning, even if it is in the fire.

There are other methods of strengthening wood against the injuries of weather, of different kinds. Cedar wood, which is a type of juniper, and has the same fruít, but somewhat larger, is covered over with wax, and buried in the ground, and at the end of seven days is uncovered, and then left another seven. Thereby it becomes much stronger and more supple. The reason is that this precaution removes much of the weight, and becoming lighter, the wood acquires a certain toughness; and if it be placed in sea water and then drawn out, it dries much faster. Many kinds of wood are put in water so they will dry out afterwards much faster than they would ' 'Theophrastus tells us' ... ib. V.5.6.

6 'Cato says' ... cüed by Pliny HN XV 33-4.

7 'Pliny writes that in a labyrinth in Egypt' ... HN XXXVI.89. Alberti had written wild plum; actually this structure, probably a Pharaonic mortuary temple, may have been lined with acacia wood. 'Theophrastus writes that wood that is plastered with asbestos will not burn'; this may allude to Theophrastus 'Aition Peri Phyton', V.15.4, although Alberti speaks only ofbirdlime. The string of names must come from another source; 'Amiantos' is from Pliny (HN XXXVI.l73). As the asbestos fibres, although mineral, can be woven, they were sometimes called 'earth flax', Strabo (Geographía X.6.1) refers to the supposedly fire-resistant towels of Carystos. Perhaps we do have a hint here of genuine attempts at fireproofing- however dangerous. Pliny (HN XXXVTI.191) lists 'polias', 'spartopolias' and 'bostrychites' as stones distinguishable only by peculiarities of coloration, without connection to asbestos.

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in air or in the sun. And this is plain to see, even though it may seem contrary to all reason that it should dry in water before it does so outside. So this wood is made very salid and incorruptible. At all events it has been well verified that chestnut wood is purged by sea water.

Pliny says that the wood of the Egyptian fig-tree8 dries much faster if placed in water, and becomes much lighter, for when it is put in the water it goes to the bottom, but when it is dry afterwards, it fl.oats on the surface [!fol. 238v]. It will be observed that woodcutters lay timber in water and in mud, specially wood which is to be used for turning on the lathe. This is done because they believe it then dries faster and is easier to work. Sorne hold the firm opinion that any green wood placed in water lasts an infinite time without decaying. Now whether this timber should be in water or in earth or in mud, smeared with dung, or plastered or coated, or preserved in the original forest, all those who have sorne understanding of these matters agree on one thing: it must not be touched or worked until at least three months have passed. The wood should dry out and cool, and so become seasoned and acquire a certain firmness before it is put to work. Once the wood is ready, Cato says9 that it should not be taken from the forest unless the moon be on the wane, mid-day and with the sun shining, with no fog, nor should the day be overcast, because the fog makes it fragile, and it decays very quickly. Care should be taken that the moon is already three or four days waning, and that the wind is not from the south. (This wind is Auster.) He further advises us that when removed the wood should not be carried over frost, {/fol. 239r] as we have said, which makes it very rough and fragile.

Timber should not be sawn before it has dried out; this is very important, even though it is not immediately recognised. But I want to warn you of it, for in time the deception and mischief in it will be recognised.

Which timbers are most suitable for building operations? Theophrastus says 10 that wood is not dry enough for boards for three years, specially not for doors and windows. All trees, or most of them, are good for building. As their natures differ, so they should be used for different things, rather than all for the same: sorne are good for one thing, and sorne for another, as I said. Sorne are better and last a long time in water, others under cover, and yet others in the open.

Oak, beech, holm-oak, chestnut, holly-oak, wild pine or maritime pine and alder alllast well in water if laid when green. Others last better if buried, others last for ever in contact with air and sun, others are worth more under cover, as walnut, cypress, elm, fir, white pine; and in the open, ash, olive and wild olive, savin, juniper. These stand up against sun and air, the others need shade. But there are sorne trees which do excellently in every place, in water, air, under cover, or in the ground. [!fol. 239v] Sorne take a better colour, others become more attractive in air, while others grow almost imperishable in water and acquire from day to day greater strength and force. Sorne are excellent for thin boards, others for use with masonry, others again are only good for floors and ceilings, where others will support weights and roofs.

8 'Pliny says that the wood of the Egyptian fig-tree' ... HN XITI.57- perhaps a reference to the true sycamore (Ficus sycomorus)?

9 'Cato says' ... - repeating from 234r, 236v.

10 'Theophrastus says' ... Historia Peri Phyton V.3.5.

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Volurne IV We will take first the alder, which is best for mak:ing stakes in water, or for the foundations of buildings where wood is involved; for this purpose it is better than any other tree, it endures clamp so well. But in the open air ít is worthless, for it does not last at all, nor yet under cover. The durmast oak is quite the opposite and does not endure any moisture. Elm is good both in the open air and under cover, and continually gets more solid, but it splits as soon as it touches water, and is not durable. The pine and pitch-pine if laid under the ground willlast a very long time without spoiling. But the oak, being a tree that is compact, solid, sinewy, tight, and full of little boles or pores, does not retain moisture, and therefore is very suitable for every kind of building, and for supporting great weíghts: it is almost like a firmament, in a building, and is very powerful. Nature has allotted it so much hardness [!fol. 240t'] that it can not be drilled unless it ís first soaked in water. Yet with all these features, there are sorne who say that it is not so resistan! above ground, nor so strong, because it becomes very brittle and fragile, and it warps, and even breaks very easily in sea water, although indeed there are three species of oak which are quire different from one another: I leave aside the hohn-oak or holly-oak; the muricated oak is another species; there are sorne very amenable for working, others very heavy, while others rapidly break or split. The wild and cultured olive and the evergreen oak are equal in all respects to the oak, but have this advantage, that they do not perish in sea water. These trees do not need seasoning in water. The holm-oak never decays with age, because it has in itself a certain liquid which preserves ít as if it were green. The beech and the chestnut have the same property of not spoiling or perishing in water. So they can be used for the main timbers of buildings, whether they be laid in the ground or in water.

The cork-tree is excellent at supporting weíghts in place of columns, and so are wild pine, mulberry, bitter orange, and elm. These trees are of great utility.

Theophrastus says that the walnut of Negropontell is very good for roofing timber because it gives a sign before it breaks. [!fol. 240v] The fu is the best of all trees for the wood panelling of rooms; it is one of the broadest trees and surpasses all others of its type in rigidity and strengtrh. The tree does not warp or bend easily in supporting a load, but rather stands firm and upright, without gíving way. In addition it ís light and does not make work for the walls of the building. We are much indebted to this tree, which can be employed for many purposes, but it does have one defect, that its wood catches fire very easily, and burns fast. But for all this fault, it is useful for roofing, as stated.

The same praise is given to the cypress, also good for roofing and for floors; it ís awarded the híghest esteem among trees, and is considered one of the most important and admirable of them. But the ancients gíve the most honoured place among the principal trees to the cedar, the ebony and the cypress of East India.

This latter they count also among the spices, and with good reason indeed, for it has an excellent scent, beauty, strength, and straightness, and lasts long without spoiling; and is almost imperishable. [!fol. 241r] What tree then can compare with this cypress? Worms never eat it, however old the wood may be, nor does it split of itself, which gives ít a great advantage over the fir, the pine, which is admired indeed, but the pine and spruce are not reckoned as good as the cypress. This spruce ís another species of pine, often called regulation timber. The first does not 'Theophrastus says that the walnut of Negroponte' ... ib. V.6.1-2- Negroponte was the Italian name for the Greek island of Euboea. But Theophrastus probably meant sweet chestnut.

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suffer much damage from worms because its sap is more bitter than that of the pine, which grubs therefore prefer to attack. The larch, which is also a species of pine, although not to be left out in the numbering of excellent trees, can be used for building and for supporting great weights, and sustains them well. There are buildings of this wood in various places. Any weight can be entrusted to for it has great virtue. It is suitable for any building, has great stamina, preserves "its vigour, stands firm against any adversity, and is not damaged by worms. There is a very ancient opinion that it is resistant to fire, and survives almost unscarred. Therefore it is claimed that if there is a possibility of damage by fire, larch boards should be erected to prevent it. Certainly, I have seen it burn, but only in the end, and like a dead thing, with a very miserable flame. [!fol. 241v] This tree has one fault, that when placed in sea water, worms get into it and gnaw it away. It is excellent for roofing timbers, while the oak is worthless for this purpose because-of its excessive weight, and the same with the olive, which is very heavy, and so presses clown on the walls of the building. And it bends under the weight as well, and buckles by itself. Further every tree that is fragile of itself and splits frequendy, is useless for roofing timber; as are olive, fig, linden, willow, and others of that type. It is certainly very remarkable what they write of the palm, that placed under any weight, it uses all its force to resist the weight above it, and when it can do no more, bends upwards to resist it better. For beams that are to be in the open, the juniper is recommended; it is a marvellous tree and good for any covering. Pliny says that the cedar is of the same type as the juniper, but much fumer and solider.

They say the olive lasts well. [!fol. 242r] The box is a tree that is highly thought of, nor should the chestnut be denied a mention, although its wood splits, as it is marvellous for exposed work. The wild olive is recommended, chiefly for the same reason as the cypress, that neither of these trees ever fracture. Account should also be taken of all the trees that have in them a fat gummy, resinous fluid, especially if these be bitter. Worms and grubs never get into trees of this type. Oearly, such trees do not receive any rnoisture frorn the outside which would be opposed to what they have within. It is believed that all trees which contain a sweet fluid, or one which has sorne share of sweetness, burn very easily, but the wild and cultivated olive is excepted. Vitruvius says 12 that the Turkey oak and beech have a nature very feeble at resisting storms, so they do not grow very old. Pliny says that the holm-oak perishes very rapidly out of the water, but the fir, especially the one which grows in certain rnountains, is marvellous for work under cover, within the house, for doors and boards and things of that type, because it is very light and dry, and takes glue well.

Spruce and cypress are marvellous for the sarne job. Beech is good for making chests and cupboards and beds, and for the hoops of casks and things like that.

13 The tree <<lecioÂť is a species of beech, very suitable for sawing into boards . They say that chestnut, elm, and ash are of litde use for boards, [!fol. 242v] although I have seen boards made of all these three, but then they do split very easily, and break; although they split straight, they do split. Equally, they say that ash is for Vitruvius says... IT.9.1- and Pliny, HN XVII.235-6. u 'Beech is good' ... 'lecio', from Italian, should here mean a kind of beech, although elsewhere, like Italian 'leccio' it must refer to sorne variety of evergreen oak. The '1 have seen' is our author's comment on Alberti. 'Theophrastus says the ancients used to make their doors' ... op. cit. V.5.6; e/ Cato, op. cit. XXXI.l. The author adds that comel may be used for gear teeth as well as pegs- being more interested in machinery than Alberti was.

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any work and endures any task. One thing is to be wondered at, that the ancients took very little account of the walnut, yet certainly everyone can see the great profit that is derived from this tree, and notably all the countless works that are made of it. The mulberry is highly recommended because it lasts well, and in the course of time the wood grows black, and more beautiful. Theophrastus says the ancients used to make their doors of black lote, evergreen oak, box and elm, because these woods keep their hardness for a long time, and are excellent for door posts. It is necessary for these requirements to turn them upside down, with the part where the root of the tree was, on top. Cato said that the arms of levers should be made of the wood of holly, laurel, or elm.

Cornel is highly esteemed for pegs, and the gear-teeth of waterwheels, and for the staves of lantern-gears; the rungs of ladders are made of flowering ash or of branches oĂ? maple. [/fol. 243r] The andents made pipes for fountains of pine, spruce and elm. But it is necessary when making these wooden pipes to lay them underground, for if this is not done, they are lost, because they split: and also if they are above ground the water spoils them, so they rot. And it has been discovered that the female larch, whose wood has a colour like honey, is excellent for panels, for painting, because it never splits, nor are any cracks ever found in it, the reason being that it has a short grain. It is wonderful too for wooden statues; for this, box, cedar and cypress are also used, as well as the thick roots of the olive and the Egyptian peach. This is said to be a tree which much resembles the lote.

For turning work, if it be something large and long, beech is very good, and so are walnut, box, mulberry, and pine: all these turn wonderfully, and may be used for smaller things too.

Ebony is for statues. For painting, poplar, black poplar, willow, hornbeam, setvice-tree, and fig are all good, because of their interna! dryness and evenness so that the paint will adhere wonderfully to them. But it is commonplace that linden is even more convenient for working than any of these. [!fol. 243v] The jujube is good for statues, but heavy. There are others which are quite the opposite, such as the oak, which never fits with other woods, nor does it keep glue well; the glue just does not take. The same drawback affects all trees which weep, orare granular, they do not take glue of any kind whatsoever. Woods which can easily be planed, that is the hard woods, take glue very poorly so it does not hold long. The same thing happens with woods of a different nature like ivy, laurel and linden. These are hot, and can not be glued to those which grow in moist places and are cold by nature. Elm, ash, and cherry, being dry, do not adhere well to plane and alder, since these are moist by nature. The ancients took great care not to stick together woods of opposite natures. Vitruvius admonishes us that boards of durmast oak should not be joined to those of holly-oak. Since I have not seen these trees in Spain 1\ I can not give their proper names in Spanish, and have therefore left them in my own tongue. ~ 'Since I have not seeo these trees in Spain' ... a comment on Vitruvius, VII.l.2- anda real crux. This sentence looks as if the author was not a native of Spain, contrary to so much other evidence that he was ... but what can 'my own tongue' ('mi propria lengua') mean? 'Ysquia' must be an Italianism for 'ischio', durmast oak (Quercus petraea), and there are others; ('Cerro'Q. cerris), 'lecio' (Q. ilex), 'ontano' (alder- Alnus glutioosa). But ÂŤcarrasca>> and most of the other tree names are Spanish enough. Was this, and perhaps other Alberti passages, translated for the author, who added his own comments, but left this exclamation of despair in his text?

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0/ trees: a summary Having dealt with all the trees in this chapter1', we should now go over the subject summarily [!fol. 244r]. All authors who write of the nature of trees say that those which have no fruit are much firmer and support a load better and more reliably than those which do fruit; and wild trees are much better than garden · or cultivated varieties, because those trees around which the earth is not worked have a harder wood than cultivated ones. Theophrastus says that wild trees are never affected by accidents, partly because they are dry. But there are also differences among the domesticated trees, specially those which bear fruit, and those which bear it early. Sweet trees are much weaker than those which are tart and sharp; those which are bitter are held to be the strongest. Those whose fruit comes late and tart, those which h ave fruit alternate years only, those which have no fruit at all have more knots than those which bear fruit yearly. And the shorter trees are, the tougher and more twisted they are than wild ones, which grow much better than those which are fertile and cultivated. They say that those which grow in exposed places, unsheltered by mountains or woods, [!fol. 244v] and much harassed by severe storms, are much stronger and thicker, but also shorter and knottier than those which grow in a valley, in a place where the wind can not do them any harm. They say that trees which grow in clamp, dark or shady places, will be more tender than those in dryer, more open spots, while those which face the north wind Boreas are more serviceable than those which face Auster the south wind. Trees which grow in places opposed to their natures throw out certain tumours or excrescences like swellings. Those which face south are tougher, but they warp at the heart, and are not straight or even, so as to be used in buildings.

Trees in places naturally dry are late to develop, but are stronger than those which grow in moist places, which grow fast. Varro thought16 that there are in nature male trees and female; and those which are white are better to work than those of any colour whatsoever. It is certain that [!fol. 245r] all heavy trees are much more compressed, compact and solid, and are tougher than light woods; the lighter the wood, the easier it is to b reak. The coarser and rougher the tree, the stronger it is. Those trees which live longer have been given or endowed by nature with the characteristic that after cutting they last longer than other trees. The more heart it has, the sturdier the tree and the stronger its nature. The part that is closest to the heart is tougher than any other, and the wood is also more close packed near the heart and will stand up to more. The reason is that as animals have their skin, so trees have bark; and flesh under their skin, and bones around their marrow.

Aristotle says 17 the knots in plants serve instead of nerves. Of all the parts of the tree, he holds the worst to be the moisture which makes it grow, although he gives no other reason than that it is subject to worms and grubs. They say that the part which faced south when the tree was standing will be the driest, [!fol. 245v] but also the weakest and most feeble, however it is the most compact and firm pan also. And the heart or marrow of the tree is closer to the bark there than elsewhere; the part which is nearer to the ground and to the root will be much heavier. The " 'Having dealt with all the trees' ... this summary is taken from Alberti's summary, chapter 7.

Cf Theophrastus, op. át. III.2.

J6 'Varro thought' ... op. cit. 1.41.4. l7

'Aristotle says' ... On Plants 1.9.1. (a pseudonymous work).

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proof of it is that if the tree be placed in water, the upper part is lighter, although that would seem contrary to all reason. And the greater the quantity of wood, the less it sinks into the water, this being understood of the whole piece of timber placed in water, when the root part hardly floats upon the surface. Yet one would think that it ought to be the opposite, having less quantity, it ought to go to the bottom, and the part that has more quantity ought to float; but we see it is the other way round. The central part will be more uneven and corrugated. The closer the grain of the wood is to the root, the more Ă­t twists. But for all that, this is the firmest and hardest part.

We find things which arouse amazement written in the best authors. For they say that the grapevine or stock lasts an infinite time18, and that in Caesar's day there was a statue to be seen at Pamplona, near Ponvin or Bionvino, made of a vine stock, [!fol. 246r] which was a Jupiter, and had lasted years without end without having decayed or rotted in the least. Indeed all agree that no wood lasts longer than the vine. In Ariana, a district of East India, there are vinestocks so thick that two men could not embrace them, as Strabo, a very weighty authority has related.

In Utica a cedar wood roof is said to have !asted twelve hundred and seventy eight years. In Spain, timber was found in a temple of Diana, which had been there two hundred years before the destruction of Troy, and !asted until the time of Hannibal.

Cedar has a remarkable characteristic; nails do not hold in it, nor does it endure or accept to be nailed. In the mountains near Lake Garda in Italy, there is a species of fu, which does not retain wine in vessels made of it, unless first greased with oil along the joints.

I have certainly overstepped my limits in this subject, and gone on too long. But there is one thing of which I am surprised that the Ancients have never made any mention of that tree. Nor yet do they speak of the almond tree as Ă­t is hard, compact, highly workable, long lasting, and marvellous for supporting weights. Nor indeed have they dealt with the apple tree, [!fol. 246v] which is very amenable to working, although it is not good for buildings, being a fragile and delicate wood.

So we see that God has made provision for men, enabling them to supply themselves with wood for their buildings from so many parts of the world, and from so many forested mountain ranges, and with such great diversity in trees, as we may see- and all for the use of man, so he can make buildings to live in. But on the other hand, we see that most flat countries lack building timber. So the Maker of the Universe has ordained that most rivers should have their origins in the mountains. There they have their beginnings, whereby we may use them, not for irrigating our lands, but just for carrying the timber out of the mountains, because we could seldom transport it except by water, on account of the many obstacles and hindrances that would present themselves at every turn. For this reason they help us out in our necessity, so that we can remedy our need for wood, for buildings to live in, and for all those machines, and the musical instruments, 'For they say that the grapevine or stock lasts an infinite time' ... Pliny again - HN XIV.9.

'Pamplona' has been retained- a weird hispanisation of Populonia, an ancient city near Piombino on the coast of Tuscany. Surely an Italian author would have known Piombino? Strabo (Geographia, XV.21) speaks only of India- this may be a third-hand reference to the banyan tree. Utica (e/ HN XVI.216) was another andent city, near Carthage in what is now Tunisia. According to Pliny a wooden statue in the temple of Diana at Saguntum had been brought to that city by the first Greek colonists, and so must have lasted a thousand years.

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and the decoration in our temples, to give praise unto the Lord and to preserve the sacred objects which are needed for the priesthood and d.ivine worship; [!fol. 247r] and for all the images and altarpieces that adom the temples of the Lord.

I say nothing of the benefits we obtain from all those bridges, and all the carts and agricultura! implements, without which the land could not be worked, and all the boats and ships, and other kinds of vessels that sail upon the sea, or on rivers.

For they are necessary to convey merchand.ise, as well asto give us information of all the regions of the world, which we could never know without them. Nor could so many great fleets be constructed in different places, were it not for the wood which comes to us from the mountains, by means of the rafts that bring us timber downstream t 9• These rafts may be made either large or small. They are employed in sorne places for transporting wood, after it has been cut and squared off. The timber is hauled to the ravines where it can be laid in the water to be carried away to the place where it is to be made into rafts, for men can hardly penetrate there, much less animals and carts. The timber is laid there in such a way, that when it rains the ravines take up so much water that they can carry the logs, to a place convenient for making it into rafts. Sometimes it is already two or three years since it was cut, during which time it can not be moved because such rain as fell was not enough to give the water the force to remove it. [!fol. 247v] So woodcutters on the mountains usually ensure that the timber is cut in a place where the water can get it out of the ravines freely. If it should happen to be cut in a place where there is no water, they take care that it will not be too much work to move the logs. There are sorne d.istricts where they carry the logs free until they can get them near to a quantity of water, and then make rafts of them there. Where there are no rivers, large logs can not be transported, because of the labour in hauling them to a point where they could be conveniently loaded on to carts.

So, in small rivers, neither long nor thick logs can normally be carried, while in other, neither small nor thick ones, because of the large rocks; like the river Jucar, which does not take any wood, neither bound nor free, unless it be planks of pine, up to four palms long. The river Tagus, being so poor in water in its upper reaches, can not carry timber at any time of the year because of its many turns; it can not even take free logs if they are long ones.

The river Segre can not move timber more than a palm in thickness. The river Guadalaviar does not carry big logs, I mean long ones, nor yet the river Cabriel, on account of its turns. The river Ebro carries very large, long thick square logs.

19 'were it not for the wood which comes to us from the mountains, by means of the rafts that bring us timber downstream' ... Literature on the timber trade seldom says much about this practice, which must also be very ancient. The author however does give the impression that he found the technique better developed in Italy, presumably in rivers coming off the Alps and northern Apennines. Of the Spanish rivers mentioned (see map), the Jucar (in the text, 'Chucar') and its tributary the Cabriel, the Mijares and the Guadalaviar (now usually called Turia) rise in the mountains of southern Aragon and flow into the Gulf of Valencia: the Tagus rises not very far off, but is the only one that flows west ro the Atlantic. The Segre, the Gallego and the Arga, the river on which Pamplona stands, are tributaries of the Ebro, the great river of central Aragon, while the Isabena and the Ara, perhaps intended by 'Anca' here, both flow into the Cinca, another u·ibutruy of the Ebro; indeed 'Anca' may well be Cinca. All these flow clown from the Pyrenees.

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The river Gallego does not carry long nor thick logs, and very few square ones.

[!fol. 248r] The river of Pamplona does not carry logs either thick or thin but only pieces split for firewood or for making casks.

The river Anca carries well grown timber, both long and thin. The river Isavena carries neither thick nor long. The river Mijares does not carry either large or small, since it does not go near any mountains. In Italy I have seen rivers which carry three layers of timber, one upon the other, and three interwoven lengthwise. In one part of ltaly I have seen merchandise carried on rafts, such as íron, copper, lead, and even loads of fírewood, and elsewhere various other thíngs. The rafts are lashed together with twisted branches of hazelwood which serve as cordage, and Illustration 316 Hatchet

Adze Axe

Inkwell for marking Compasses

Line

Le ver Roller Auger

Roller

oars are carried on them: however not to make them go, but only to steer them, when they get into the current, or to keep them from a collisíon. Although oars could be used to help them along, yet as the water moves them on its own, oars are only placed fore and aft, in number according to the size. The most that I have Illustration 317

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seen on one raft ís eíght, but I have seen only two, four and six. (It is understood that they are all to be placed fore and aft.)

This section has been inserted as being connected with water, [!fol. 248v] and also because Vítrívíus puts it in his work. Thus we receive so many benefíts from wood that even if there were no more profít in it than chaírs, saddles, and all our tables and beds, that alone would be a very great pleasure, with so many things especially of wood, that are useful for socíety. (lllustration 316) These are the most common tools used with timber in the mountains. Those who work the rafts only take an auger to drill the logs, and hatchet for chopping -to make oars and cut binding- and poles for punting the rafts, and for locking with the binding. (Jllustration 317)

[!fol. 249r] In many areas there are rivers that can not be navígated by rafts or anything else, not even to carry a single free log, on account of all the rocks in the stream. But I have thought of something which I believe would be of use in such a river; that is to construct a path of boards, which should be of su eh a width that a log could travel freely along ít, províded that ít does not have any corners because they would be a great nuísance. Where there might be a rock which will form an obstruction, break it, because there would be much less expense doing that just the once than havíng to convey the timber on carts all the time, as the cost of cartage is very steep.

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SEVENTEENTH BOOK Introduction Book of stones and other building materials Stone was the major building material of eastem Spain, as of Italy, and the subsequent libro on stone bridges is evidently pretext enough for an account of the stone used in structures, with notes on the properties of various types. The qualities desíred have changed but little. A modero handbook (Smíth 1966, p. 129) lists the main characteristics required as '(1) strength, (2) hardness, (3) workability, (4) durability, (5) colour and grain, (6) porosity and texture, (7) ease of quarryíng, (8) accessibility', all of which feature here. However, for architectural writers of that day, assessment had to be very rough and ready, based only on features that appear immediately to the eye.

Other inorganic materials used in construction, lime and sand, bricks, adobe, tiles are then treated also. The drawing of the woodsman's tools ís here complemented wíth those of the quarry; then working of lime and gypsum receives detailed explanatíon, with pictures of all the equipment in regular use; brickmakers are shown at work, and patterns suggested for tiling and for brick floors.

Although inspired by Alberti (II. 8-12), even as Alberti was inspired by Vitruvius (II. 3-7), this book refers much more frequently to Spanish material than the timber section.

Alberti in fact drew m u eh of his information from just two books of Pliny (HN XXXV-VI), and consulted stonemasons and quarrymen less than he claims. As ever, what an Ancient author wrote had greater authority than contemporary craftsmen. Our text however clearly does slip in many remarks about practice in Aragon. The illustrations of the tool-kit of the quarryrnen and lime-burners show that he was attempting to be more comprehensive than his sources, describing techniques about which they had not bothered.

The book does open with an Albertian passage on weathering stone, followed by observations on the qualities of yarious types of stone. These are distinguished mainly by colour markings, and texture, in such a vague way as to make ídentifícation difficult.

Modero commentators on Alberti have wisely been cautíous in asserting which type of stone such accounts describe, seeing that our modero identífications are based on a geochemistry and a historical geomorphology unknown in the Renaissance. Hence the whole passage reads like a series of disjointed notes, our text addíng one or two to Alberti's collection. No doubt there were names used in the quarríes and in the building [483]

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trade already; sorne Italian terms have entered general use; two of them are mentioned here, travertine and pozzolana. Our text also includes a few Spanish terms not now in common use.

After inserting his pictures of the stonemason's tools, the author goes back to Alberti [252v], but although all Italian and the more exotic places and persons come from this source, no passage in all the Twenty-One Books contains so many Spanish names, which suggests as do the drawings a personal acquaintance with the building stones of Aragon and with methods of construction.

Lime and mortar for building get a section of their own, as they do in the sources, [256r], but here a remark by Alberti on creatures found live within stones and zoomorphic fossils encourages our author to give a fascinating list of fossils he has seen himself in Aragon. It is only a pity there are no pictures, which would have been among the earliest illustrations of fossils.

Lime and mortar lead naturally to sand [260v-262r], and sorne notes on curious alternative substitutes for ordinary building materials, interpolated before an account of gypsum manufacture, and of alabaster, largely independent of Alberti, which again suggests direct knowledge; this is one of the first good accounts of the production of these materials.

Brick follows; comments are so intertwined with the paraphrase of Alberti, that sometimes a sentence in which <<l>> means Alberti is dosely followed by one in which the author gives bis own first person observation. It does appear however that he has consulted Vitruvius directly here, and possibly Pliny also. The notes on adobe and its Moorish origins, and the extended passage on ornamental tiles, are as might be expected not found elsewbere. Indeed the information on tiles does not appear in any other architectural handbook untillong after. After all, this text was compiled in the dassic land of tiling; what in Italy was a minor craft, here was a very popular and successful feature in the aesthetic of interior and exterior decoration, in walls and floors alike.

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Chapter on stones in genera~ and at what time they should be hewn at the quarry, and at what season they should be worked, and which are the most easily breakable and which the hardest

reat care should be taken with stones that are to be used in construction, especially in the walls of buildings; and likewise with the stones of which limeis to be made. We shall deal with this briefly, as the subject is well known among the common people, being so simple. There is no need to recount the causes, whence stones take their origin and principle, [!fol. 249v] leaving aside the differing opinions of different philosophers; as it is not relevant to our subject; we shall continue to adapt ourselves to the craftsmen who deal with it and not bother about these opinions, as I say. Cato used to sayl that stone should be hewn or removed from the quarry in summer, and kept exposed to sun and air for two years befare it is placed in the work, because if it did not make any movement in those two years, it would not do so in the work either- through having been in the sun, air, rain, frost, and mist; and thereby its goodness will be known by the weathering it has undergone. But if it be worked straight after it has been extracted from the quarry, it will be full of its own moisture; and sorne stones disintegrate, and others split, after contact with frost, air, sun and rain. So after they have been taken from the quarry, the stones should be kept in a place where they are exposed to the weather, and those which stand up to it, show their quality, if they are soft or strong. Then it will be seen in which stones you can have confidence. By making this test, the craftsman is reassured of the quality of his stones, for no kind of stone should be worked without first obtaining information as to its goodness and quality, for there are sorne kinds of stone that in the course of time decay like wood [!fol. 250r] and disintegrate of themselves, while others burst or crack under frost, and others are eaten away by exhalatĂ­ons.

G

Thus the opinion of the Ancients was not to use any stone in their work befare two years had past, and this they did in arder that if the stone should have any 1

'Cato used to say' ... actually Pliny (HN XXXVI.l70).

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fault, it would be marked in thls time. Oearly in the same species of stone there may be two qualities, so the same thíng may be found, one hard and one soft. There is one kínd of stone that after removal from the quarry will barden in air, and others which crumble when frost touches them, and others again that break or split with time. But those craftsmen who have great experience know well how to recognise and distinguish the good stones from the bad. Por the value of stones is much better learnt from ancient buildings than from the writings of philosophers. However we should speak of all the varieties of stones. In short, I say that with all the respect that is owed to the wise, it is still permitted for me to speak.

I say then that all white stone is softer than red. And transparent stone is more workable than dark, and the more closely stone resembles rock-salt the more difficult it will be to work. [!fol. 250v] Stone that looks as if sand has been thrown over it2, and sparkles like glass, will be very rough and coarse; and if it has sorne little shining pieces mixed in, like gold, it will not be a stone to suffer anythíng. If it has sorne little black poínts, it will not be possible. A stone which has spots: if the spots are like drops with angles, the stone will be strong and safe, but not if the drops are round; and the smaller the drops or spots, the better and harder the stone. The stone will be more durable if it has a clear, clean colour. It will also be more durable in the work if it has less veins, and the more closely the colour of the veins conforms to that of the stone, the more even its texture. The thinner the veins, the more beautiful the stone. But the more twisted, confused, and fragmented the veíns are, the rougher and coarser the stone; and the more knotted they are, the cruder it will be. Stone which splits easily will be the cheapest. Those stones which have in the middle a russet or a yellow vein will easily decay. And the stone that has spots, sometimes white sometimes grass-green, will be of the same type as the above said, which spoils easily; and the green stone more so. [!fol. 25lr] Norte of the others is as refractory as the stone that looks like clouded ice. Many veins signify that the stone lacks strength, it will rapidly break or collapse. The straighter the veins, the less confidence can be put in the stone. The finer and smoother a stone appears when cut, the more compact it is. If at the time the stone is broken, its outer surface looks less rough, it will be better for working than if the outer surface is rougher, for then the stone will be coarse and rough.

With coarse stone, the whiter it is the less it allows working with tools. Black stones are the less amenable to the worker's tools, the more they retain their roughness and coarseness, and are small-grained.

All stone is of less value the spongier it is, I mean that the more holes it has, the harder it will be; although there is a stone with boles which is very soft; they call it caracolina, snailstone. It is very good in water.

It is true that there is a type of stone which has holes and is red, which is very strong, and laborious to work: and there is also a yellow one, with still yellower spots, which is very strong. There is another stone of this same colour, but it has no spots, which is consumed of itself, and is very weak. When stone has been 2 'stone that looks as íf sand has been thrown over it' ... a very coarse sandstone- or perhaps quartzite? The 'shining pieces' sound rather like pyrites, while the references to 'drops' and 'blotches' may be a breccia. Then again, 'the stone like clouded ice' further down could be quartz. But such identifications are necessarily tentative. The wugh black stone may be basalt.

Since 'caracol' = snail, 'caracolina' is probably a fossiliferous, shelly limestone: it is here inserted into Alberti's account.

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evenly or smoothly moistened, [!fol. 251v] the longer it takes to dry, the cruder it is. The heavier any stone is, the firmer and safer it is, and the more easily it will take polishing, compared to lighter stones. All other light stones crumble easily when worked, which those we have named above do not do. Stone which when struck gives off a clearer sound is better, as being more compact and tight knit than that which gives a dull sound. That stone which on being rubbed vigorously gives off a smell of sulphurJ, will be very strong; that which has no such smell, will not.

The more stone resists the tool, the stronger and more robust it will be to resist the damage of weather and storm. There is a belief that the larger stones are in the quarry, and the larger they can be when removed from the quarry face, the more resistant they will be in the work to every adversity that can befall them, more than any other stone of any kind whatsoever. However soft any stone may be when taken from the quarry, after it has been exposed to the air and to moisture, it becomes pliable. And it is better for working after it has been soaked in water, than when it is dry. And if it is wet, and then dries, it will have a closer texture. [!fol. 252r] They also claim that it will be more workable when the wind blows from the south, than when it is northerly, for the stone is then more liable to split than when there is a south wind. But if someone should decide to make this experiment- when you will have two kinds which you have worked when those two winds were blowing; then wet sorne but not others, and if the stone that you have wetted grows in weight, it is a sign that it will decay, and resist neither the heat of the sun, nor the weight of the load it will have upon it.

(Illustration 318) The hafts of picks and hammers should be thin, because they will then give a better stroke. These tools are for extracting stone in the quarry, [!fol. 252v] and are all that is needed for this trade.

On the qualz'ties o/ stones) and the method o/ making tz'les and other earthenware decorations /or buzldings The ancient philosophers have said things worth knowing about stones, of great marvel, and of their varieties, and how each one can be applied to its necessary function. Near the fields of Bolsena, in Italy, and the place called Stratone4, there ís a kind of stone which is wonderful for every kind of building. It ís resistant to fire, and to everything else that could cause damage, and so it lasts very well. It ís an incorruptible stone. This kind of fire-resisting stone is to be found in countless places, for wherever ovens are made for baking bread, it may be supposed that there is sorne of this species of stone: and that is a great truth. There is also another species of stone which resists fire even more than this; of which crucibles are made, to hold glass in the furnace, sorne being found near Calatayud, and countless other > 'stone which on being rubbed gives off a smell of sulphur' ... perhaps refers to sorne bituminous substance in a limestone.

4 'near the fields of Bolsena ... and the place called Stratone' ... Lake Bolsena is in southern Tuscany; Stratone must refer to the Statones, an Etruscan people of that region (HN XXXVI.168).

The stone is presumably a tufa; that utilised from the Alban hills for the reconstructton of Rome after the great fire (Tacitus, Annals, XV.43.3) was a peperino. The Roman walls of Saragossa are limestone too: a section remains. The refractory clay found near Calatayud is well known.

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I/lustration 318 !ron Mallet.

Spike Thick Wedge Pick with sparrow beak head Pick wi.th heavy back Wedge Pick with diamond head Pick with cutting blade Adze or cutter Iron crowbar Mattock Double-headed piek Stonemason's hammer Harnmer head mattock Mallet

places. So we see that this stone must be very resistant to fíre. It is very good for working into statues. [/fol. 253r] Tacitus writes that when Nero rebuilt the city of Rome because of the great conflagration he had made, he used the stone of Albanum and Gabinium for beams, as this stone resises fue. But the stone which Julius Caesar used for the walls of Saragossa is quite the opposite. As soon as it feels fire it is turned to gypsum, although it is a marvellous stone if placed in a position where fire can not affect it. It lasts for ever, and may be used in any kind of building. It is white, but tending to ash-grey.

In the territory of Genoa, and that of the Venetians, and many other places, specially in Aragon, in various parts of that kingdom, a species of white stone is found', which can easily be sawn like wood and alabaster, and worked with tools like wood. This stone is resistant to any strain. But there is one species of this stone which is extremely white, and crumbles by itself: but sorne 1 have seen as wlúte as snow, and yet it kept great stability for anything that might be entrusted to it. lt is remarkably workable, and suitable for every kind of building. In Istria there is a species of stone wlúch closely resembles marble, but it is such that it splinters if touched by steam or flame. [/fol. 253v] And this holds for every kind of very hard stone, especially white flint- but the black ones too can not endure fire at all. A species of stone is found, ash-grey in colour and very dark, in which it seems that sorne coal must have been mixed. It is quite light, and very suitable for working, and wonderful when placed in the work, for it resises any strain. There is sorne of this type of stone at Madrid. If it rests unevenly for a considerable time over something, it warps like wood. it is so dry that it attracts all the moisture of the [488)

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mortar and absorbs it; when they want to work it, they wet it, and then the surface of the stone rises. There is a type of this stone that absorbs all the moisture of another and leaves it like dust, quite useless, so that within a short while the building is ruined because the lime does not unite with the stone. But round river stones have the opposite property, they never make a good join with lime, because of the quantity of moisture that is in them, and so it never succeeds in binding.

There is a whitish stone, which has holes in it, and snailshells. It is very good for working, and suitable for every kind of building, specially standing in water, where it is wonderful, for after water and moisture have touched it, a skin forms over it, which makes it very strong.

[!fol. 254r] In Aragon there is free stoné in various places, chiefl.y in the territory of Teruel, in Cañada Vellida, and in the territory of Roca, in Gallocanta in the county of Belchite, Pobla de Abortón, in the county of Aranda, in Epila: but from what I have seen, the whitest is in Alquezar and Lencina. In Fonz near Monzon, in Leciñena near Saragossa, at the Muela on the limits of the city; this is the softest of all, and also the darkest of all that I have seen- and there are countless places near T olosa. This stone of which we have been speaking is wonderful for making mouldings, and figures, and all kinds of work. There is sorne too which is very good in the magistracy of Montesa. In Aragon many varieties of marble itself may be found.

It has been discovered that with Travertine stone, many pieces consolidate by themselves7 into a single piece. This joining together into one is caused by the moisture of the earth, over the passage of time. It has been observed that near .where Lake Pie di Lobo8 in Italy falls or is precipitated into the river Nera, the stone keeps growing on the river bank from day to day, so sorne people believe that as the stone has increased, it has closed the outlet of the water into the valley, [!fol. 254v] and so has caused this lake to form. Below Basilicata, not very far from the river Sebari where the water falls from such high banks toward the east, very large pieces of stone are seen to grow each day, congealing on account of the water.

These stones hang over, and are so big that one alone would be enough to load up countless carts. Befare this stone is extracted from its site, and even afterwards, it is very soft; but after it dries out, it turns very hard and is suitable for all kinds of buildings. I have seen likewise, with this stone, that the pipes of a fountain had been closed up with a material so strong that material and pipe had conglutinated into a single piece of stone: and in another place I have seen the water keeps loading daily a material which is turned to stone; and thus it may be seen in various places how stones grow. It may be observed on mount Monguy, near Barcelona, where an ash-grey stone is extracted for use as millstones, that where sorne of this ' 'a species of white stone' ... presumably chalk. The Istrian stone <<like marble» must be a limestone. The 'ash-grey stone' at Madrid replaces Alberri's Italian references; it may refer to the granite north of Madrid, which contains black mica, which could gíve the impression that sorne coal 'must have been mixed' in it. But it is not light.

6 'In Aragon there is free stone' ... workable quarries in severallocalities- see map. 'many pieces consolidate by themselves' ... a calcareous deposition.

'Lake Pie de Lobo' ... a Spanish forro (literally, wolfs foot) of the Italian Pie di Luco, a lake near the famous falls of Le Marmore on the Nera in central ltaly. 'Sebari' represents Bartoli's 'Silari', now the Sele, which rises in the southern Apennines of Basilicata. Our text replaces s~me of Alberti's references with Monguy (now Montjuic) in Catalonia. All these 'growths' are accrenons of calcium carbonate. from the streams.

7

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stone has been removed, at the end of ten to twelve years the stone ís found to have grown agaín, and to have closed and filled the empty space. There are different opínions on thís: sorne claím that stone grows in its own place, wbile others say that the earth whích falls into the empty space, [!fol. 255r] ís converted into stone. But all agree that it grows, and that the same stone is rísing upward. On the way to Florence9 , near the river Chiana, there ís an estate whích ís full of very hard stones in great abundance, whích look as íf they had been placed there by hand, and every seven years they turn into clods of earth. Plíny writes that near Espiga and near Cassandría, clods of earth turn into stone. Close to Pozzuoli in Italy, one league from Napks, a powder is found which when kneaded wíth sea water, hardens in such a way as to turn into stone. Diodorus writes that in Arabia there are clods of earth which when taken from their place have a marvellous gentle odour; if put on the fire they dissolve or melt, and run off like metals, and then on coolíng are transformed to stone. If they are put in buildings, and rain water touches them, they turn soft, in such a way that the whole wall after it dries turns to a single stone.

At Assus in the Troad, the sarcophagus stone is extracted. It has veins whích split easily. And if a tomb is made of thís stone, and a dead body placed therein, it is consumed; body and clothes are transforrned into that same stone, except for the teeth, which retaín theír own material. But anything else placed in it is transformed into stone.

There is another stone, quite the opposite of thís, [!fol. 255v] the stone Quernites, which preserves dead bodies for a very long time without lettíng them decay. King Darius was buried in a sepulchre of thís stone. But íf all the types of stone that exist were to be treated here, wíth their effects and virtues, there would not be a book big enough in the world, since there are so many types that all that I have written here is no more than a summary. Por I have not discussed marble, nor alabaster, nor porphyry, nor serpentine, nor jasper, which has so many colours and different spots, but have only dealt wíth the common stones used in building. A lengthy discussíon would be needed only to deal wíth the species of sandstones, how much more then the stones which are associated wíth gypsum of different colours, and the bastite stone, which is black, and of which there are various types, as sorne are very hard and sorne very soft. I leave aside mixtures and compounds of one wíth another, for there is a vast ocean of coloured stones; and various types of light coarse stone. Those whích are engendered by water are marvellous for ashlar, for vaulting arches and tracery, ·because they are as light as wood, and can be worked wíth an axe, just as timber is squared off. I leave aside stone of a single colour, yellow, red, blue, green, black, tawny, whíte, and countless other colours, like crírnson, dark brown, violet, and so on. 'on the way to Florence' ... these hard stones may be flints, gradually buried by topsoil.

'Pliny writes' ... HN XXXV. 167. Cassandria was in Macedonia. But 'Espiga' is mysterious; the name replaces Cyzicus, an ancient city on the Sea of Marmara. Pozzuoli (here Puzol) is the original source of pozzolana.

'Diodorus writes' ... a string of dubious Ancient tall tales; e.g. Diodorus Siculus, Bibliotheca Historiae II.49. Assus was a town in the Troad, the north-west corner of Anatolia, although the sarcophagus story (from Pliny, HN XXXVI.l31) may mean that quicklime was put into the tomb to speed up decomposition. The «quernites» (or 'chernites') is also from Pliny (HN XXVI.l32)who had it from Theophrastus. It may be onyx marble.

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What type o/ stone zs best /or making mortar [!fol. 256r] Mortar is made from various stones10. There are different opinions asto what it should be made from; sorne say, the harder the stone the better the mortar. But others hold to the contrary, that the lime will be better when it is made of a moderately hard stone, and that it then bakes better, whereas when it is very hard, it never bakes completely, sorne stone being left. And after the lime has been laid in the work, this stone crumbles into powder. Cato the Censor disparages mortar made of different types or kinds of stone, nor does he like mortar made of pebbles, which he says is good for nothing. Beside the fact that making it of whole stones is uneconomical, I have seen mortar rnade of round white river stones, which are wonderful, and not bigger than a fist. This stone is very greasy and full of such a moisture, that after it has been baked and slaked it goes like butter. Lime made of snailstone is worthless. Lime made of coarse stone which is somewhat glassy, will be a very rough mortar. The mortar made of flint stone will be wonderfully good. All mortar needs to be greasy in order to take better. [/fol. 256v] The worst mortar is that which is made of a stone which crumbles by itself when baked on the fire, which can only consume it-like coarse stone which is very dry in itself, as happens with light desiccated stones. Stones which are very white, of a deathly pale colour, are no good at all, for the stone has to be heavyin baking it should lose a third of its weight in the crude state. Likewise, stone which is very greasy and full of moisture is much more disposed to vitri.fy, in such a way as to be quite unsuitable for a good mortar. Pliny says that green stone is no good for mortar, because it never bakes completely. This is serpentine stone, of which there are many species, but I can not identify the species he is discussing.

He says that it is highly resistant to fire, and the same is to be seen in porphyry, which does not burn and does not even let any stone round it burn, if there is contact. Stones which are somewhat earthy and have earth mixed in with them are worthless for making mortar, because it does not come out clean.

Ancient architects praised highly mortar made of a very hard, compact white stone specially for doing anything in a building, as it takes wonderfully with the stone. This mortar the ancients put in the first grade, [!fol 257r] the second being given to the mortar made of light spongy stone. Although this mortar is made of a stone that usually spoils, there is sorne good in it for whitewashing walls, and making them white and shining. In France they normally use no other mortar than what they make of certain stones, no bigger than a fist or an egg, which is collected in the river beds. They are blackish, very hard and look like pebbles. For all that, placed in the work, it is marvellous whether with stone or with brick. In París, they normally usell a species of white earth, which is neither mortar nor yet gypsum.

When wet it is wonderful for work, takes very well with anything that is a mixture and never perishes even though the stone or brick may spoil. This material they called plaster.

10 'mortar is made from various stones' ... largely derived from Alberti; but Cato (De Agricultura XXXVIII.2) ís really cited from Pliny (HN XXXVI.174). The comment on the use of mill stone (257r) is from the same passage, the «green stone» from XXXVI.169. Alberti thought he meant a porphyry, but our author may be right for serpentine does often have thís colour.

11 'in París, they normally use' ... only our author mentions plaster of París in this context.

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Pliny writes that the stone from whlch millstones are made is wonderful for making mortar. I have seen mortar made from millstones, whlch had sorne spots like glass. lt was a very rough harsh lime, and very dry too; and the drops were like rock -salt, so that the stone sparkled. That whlch does not ha ve these spots, is a very compact and solid stone, and if when it is worked, the dust that comes off is very fine, it is very good. [/fol. 257v] Any quarry stone I say, will be better for mortar than stone which is collected. And the best will be the stone extracted from the quarry where the sun does not touch it, and better where there is sorne dampness than where it is dry, and better the mortar of white stone than that made from blacker stone. In France, in the maritime regions of the Eduy people12, they make it of sea shells and oysters and the like, through not having stone.

Mortar after being burnt and taken from the kiln must be placed where neither sun nor moon nor wind would touch it, especially in summer, for it would crumble and turn to dust. It should be put in the shade, in a dry place. If it is left in the kiln, it becomes useless. lt should be slaked and then preserved as I have said, that is in the shade and not in the sun, for it would get very coarse, and take badly when laid in the work. lt should be observed, and care taken, with stones, that before they are put in the kiln, the large stones should be broken up into pieces- however not smaller than a man's head, because then they will be more convenient to handle and put in the kiln, and will bake more easily. Sometirnes in round stones a hole is found in the middle, which causes great damage in the kiln, as air is enclosed in the holes, [!fol. 258r] whlch causes the kiln to blow up, and lays all in ruins. For when the fire begins to work on the outside, the cold keeps fleeing the heat, and the air is enclosed within the stone, so that the fue causes the stone to be transformed into vapour. lt is quite certain that the stone swells up in the kiln, and so explodes, and then everything is ruined. But if the stone is broken up, all these nuisances and difficulties are avoided, whlch could otherwise occur. Sorne clairn that in such stones they have seen certain worms, which have many feet, and whose back is covered with hair. These worms do great damage toa kiln.

Since we have begun to recount the strange things 13 whlch happen to be found in stones, I have seen a stone, which when they were excavating for a foundation, was broken in a way like when a meat-pie is opened- and inside they found a stone snake, which had all the scales it would normally have. It was detached from the stone and brought to the Archbishop of Saragossa, Don Hernando of Aragon, in Tolosa. In King Francisco's time sorne quarrymen found a free stone with a live toad enclosed in the middle .of it. Nothing was to be seen whereby it could have 12

'in France, in tbe maritime regions of the Eduy'... the Aedui, an ancient Gallic tribe really lived in tbe centre of France, in the region of tbe upper Loire. Presumably 'oysters' (perhaps fossil?) misled later writers. l } 'Since we have begun to recount tbe strange things' ... Alberti's weird worms were probably fossils; he adds the live snake found near Rome (according to him, while Martin V was Pope, 1417-31), as were the (probably echinoderm) five-leafed stones from Verona, which evidently inspired this fascinating digression. The stone snake could well have been an ammonite, or possibly traces of worm, or reptile tracks. The iron nail could be a natural iron concretion. Otherwise the author sees, as with tbe fossil wood, and the crabs, shells, snails that these fossils are just like tbe living creatu1·es. However tbe heart-shaped stone could well be another echinoderm. As for the toad in the hole stories, they were widespread. Probably the animal had found sorne small crack in the rock, while the Maltese fish were almost certainly living in fissures of the shoreline rock.

Hernando de Aragon, grandson of King Ferdinand, was archbishop of Saragossa 1539-75.

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got in, and the part where it lay was much harder than the rest of the stone- [/fol. 258v] and as soon as it saw the air, it died. It is believed that it had hardened in that place through licking the stone. On the island of Malta, there are sorne rocks near the sea, as solid as can be; but when they are broken open little live fish are found, inside, which are even good to eat. Near Rome sorne quarryrnen found a live snake inside a great stone, which was hollow in the centre, and it was enclosed on all sides. Near Monzon a master working a stone found quite a large iron nail in it.

I have seen countless things in stones, which were very different in character frorn the stone itself. I have seen crabs transformed into stone, inside another stone, but much firmer than that stone. I have seen frogs inside stones, also of a stone firmer than the stone itself. I have seen fishes and scarab beetles, I have seen a piece of stone which had first been a trunk of a tree, since it had a knot in it with the same veins that pine wood usually has when water is poured over it, so as to leave them higher than the rest. I have seen various things of this type, such as little animals inside stones, shells, snails, forrned by thernselves, without being in sorne other stone, with all the lines which the natural ones in the sea would have. Near a city in Italy called Verona, there are sorne stones like flat onions, which have a flower with six leaves, like what is made with a cornpass in a circle, with little veins, like blue lilies usually have. [!fol. 259r] But rnost have five, so they look as if five olive leaves had been put together to make that flower. I have seen stones as rnuch like hearts as could be, with those details that hearts of flesh would have; and countless other stones. I have seen stones which look like animal bones 14 , rnade of a material which ran out of a rock, and were of the sarne colour as it. And I have seen stones which seerned by nature like white coral, with its knots. I have seen sorne stones, which were nourished by the rnoisture which seeped frorn a rock, like grapes- really like them even to the pips, but they were three palms in length. They were hangĂ?ng frorn the roof of a cave. That was near Roda in Aragon. And the others, like bones, were in the county of Rivagorza, and the white corals were in Catalonia. So if I were to describe all the stones I have seen, stones like coined money, with a kind of letters, an.d sorne sort of figures ... I have seen stones which really seemed lentils, in shape, colour, and size; in one cave there were so rnany round stones, as if they had been made in a rnould, and almost all of the same dimensions, a cartload of them.

15

Now let us return to the subject we had begun. Here I shall not bother to keep recounting the rnethod of rnaking the lime-kiln, nor how they begin to set up the stones, nor how they close it, [!fol. 259v] nor yet where the fue should be located, as all these are matters well known and cornmonplace. Nor indeed how one should start the fue. There is one thing I want to note, that when the fire begins to take, it rnust do so gradually, until the stones begin to sweat, because otherwise nothing would come of it, nor would the stone ever roast, if it did not first sweat in the kiln; so let the fire take little by little, until the flames reach the top of the kiln; then give it a great spurt. This is the cause why sorne kilns burst;

1 ~ 'stones which look like animal bones' ... as they were ÂŤmade of a material which ran out of a roclo>, these are surely stalactites; those like bunches of grapes are botryoidal stalactitic aggregates.

The corals would be of the same origin, whereas the stones like money or lentils could be fossil Foraminifera.

15 'I shall not bother' ... in fact he does give advice on the management of the lime-kiln, as well as having it depicted. Basically, the process is one of calcining the limestone to quicklime.

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Volume IV it is because the fue was made too vigorous before the flames had reached the top, and as the moisture was not exhaled, it was enclosed inside, and necessarily had to burst out and blow off somewhere.

So the flame should go up to the top, without any smoke mixed in with it, and the highest stones should begin to flow. Nor on this account is the kiln fully heated until the stone begins to swell and keeps splitting and opening, and the stones descend to close the opening. It is a wonderful thing and also to be noted, that when the lime kiln is roasting, the Eire has this property, that it begins to grow cold below, while the fire is still in the lime in the upper part of the kiln. When buildings are made with lime, sand must be mixed with it, since lime alone grips very poorly, [!fol. 260r] because it is dry by itself and that is why sand is added, in order that from these two extremes a good cure may be provided, for the moist mixed with the dry, and the cold with the hot, form a temperament which is very strong. This is done in the way that copper is mixed with tin, as they are both soft by themselves, but mixed together form a very strong medium. And lime does the same with sand, forming a third material, different from either, although in the mixture there is more of the one than the other, justas in bronze, there is more copper than tin, so here there is more sand than lime. (Illustration 319) Illustration 319 How the stone goes in the

kiln Lime kiln

Poker Shovel Scoop.

Mattock for stirring the lime Spade

[/fol. 260v] These are the instruments which are needed to make lime and slake it and make mortar of it, for use in construction. (Illustration 320) There are three kinds of sand mixed with lime 16. One is from pits, one from rivers and one from the sea. Although many do not distinguish between sands, yet 16 'there are three kinds of sand mixed with lime' ... sand too gets a chapter to itse!f in Vitruvius and Alberti, on whom this section is based (II.lO). Vitruvius (II.6.6) does recommend sand which

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Illustration 320 Pail Small Basin Basin or trough Basin Mortar of lime and sand Fose

UaJnttt rnaftJ1 Ár(atún.a ...)

_

:."\ ..-::_ ,...

r · ..... - ..

there is a great difference in their taking with lime, as sorne of them do ít very tenaciously.

Of the three dasses or types of sand, the first and best is that whích is taken from píts. The second ís that deríved from rívers, and with it ís counted the sand made by aíd of the rain, which ís better than that of rívers, because ít is less modífied by the water. And the third species ís that of the sea; it is the most useless of them all. [!fol. 261r] Pit sand is of different varieties, as different as the places from which it is dug, since there is a white species and a yellow one and a reddish one, another that is ashen in colour, another the colour of fme charcoal, and countless others. Sand is certainly formed from stones reduced and gradually worn away, until they have so diminished that they can not get any smaller unless they become dust. Vitruvius praises the sand which is of fine charcoal colour more than any other. Of pit sands, the white is held to be the worst. Gravelly sand is very good for foundations, when ít has in ít fine stones, no bigger than the largest nuts. But the best sand is held to be that composed of thin fine little stones, which the Italians call fine ghiaía, gravel, but here is called grainy sand: it comes with the floods. A sand called cantoluta, ís like the gravelly, but much finer, like thíck pinheads, and ít has nothing of the earthy in it. And after this, river sand comes in second place, once the coating of dirt has been removed. [!fol. 26lv] The sand of torrents is better than that of rivers, especially that found at the foot of mountains, where the mountain is very steep. The last is the sand taken from the sea shore. It is black, and shines like glass. Sorne do praise sea sand, and say that it is as desirable as pit sand, but the type they esteem is not to be found everywhere. For they say that the sand along a shore facing south is the most worthless of all sands. But the regions whích face a south-westerly direction have very good sand. But of all sea sands, the best is certaínly that which is found under appears 'carbunculus', although not so exclusive!y as is implied here. 'Ghiaia cantoluta' is an archaic term, used at that time in the Tuscan building trade for grave! whose grains are coarse and sharply pointed.

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cliffs, and has a thick grain. It is also certain and has been investigated, that there is a great difference berween sands, because sea sand dries out with difficulty; it is naturally stícky and always clamp, and does not run, because of the salt in it; and for this reason it does not hold firm in construction work, particularly where it would have to support great weights. River sand is not so clamp, and therefore is much more suitable for such work, especially for dressing walls.

Pit sand is strongest because of its heaviness, but in work it cracks a lot befare it is smoothed clown, and therefore this kind of sand is better for making vaults than for plastering walls. But of all sorts of sand, [!fol 262r] that will be best which when we take it in our hands, and keep squeezing it between them, makes a sound like something rough. And also that sand which when placed on a white cloth leaves no trace of earth, or stain upon it. On the contrary that which is fatty, and not rough, and has the smell and colour of earth, like a reddish colour, will be bad sand.

That sand which when put in a vessel containing water, and the water stirred, does not make it turbid is good sand, but if the water does become turbid, then the sand will be bad, having too great a proportion of earth.

If sand after it has been dug is laid in an open courtyard and then in a few days sprouts grass, that sand is not good. If after it has been extracted, it is a long time exp osed to air and sun and moon and frost, it will turn to earth again, because it gradually decays, especially when it is of the type that produces bushes or wild figs, and this qualíty of sand is foul and bad, and worthless for mixing with lime, since walls made with the like sand, will not last for long.

Now we have dealt with the woods and the stones, and the lime and the sand, which the Ancients praised as very good- of which I see that today no account is held of them, and they are considered of little importance in the judgement of many experts who deal with these matters every day. Yet it certainly is very important, although it is not noticeable immediately in the work, [!fol. 262v] and that is why buildings put up nowadays last no longer than they are líved in.

But let us return to the subject. We do not find all those things which are necessary and suitable for construction in every place17 • Cícero says that Asia is very abundant in trees, and that is why there are so many buildings there, for it has always flourished with buildings and statuary or images of marble; but marble is certainly not to be found everywhere. There are sorne places that lack stone, never mind marble for building, there is no variety of stone at all, and others where, if there is any, it is unsuitable for building. In many districts there is no pit sand; but 17 'we do not find aU those things ... suitable for construction in every place' ... this list of peculiar building materials is raken from Alberti. However he cites Cicero for Asian abundance of marble, not trees, which does not make sense. For Babylonian asphalt, HN XXXVI.l82; and mud at Carthage, 169. Herodotus (Histories IV.108) describes the Budini who inhabited what is now eastern Ukraine; the Nervi or Neuri were their neighbours. Such 'facts' appear first in Herodotus and other early Greek writers; they were still being retailed by those anempting encyclopaedic geographies and histories in imperial Rome, like Pomponius Mela and Diodorus Siculus; and as was remarked in the hydrography of Vol. I, were still current in the sixteenth century. The cave dweUings of Sardinia may be the mysterious 'nuraghi'; our text converts Diodorus' 'India' to the 'East Indies', without referring to any contemporary traveller's account of the region: did any people of the Indian Ocean ever really build their homes of whale-bone? In all this, the author inserts a reference to reallife- in the treeless plain of the · Terra de Campos in north-eastern Castile, people still used cow-dung for fue!.

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Seventeenth Book in others there is abundance of everything necessary for construction. Pliny says that the Babylonians used asphalt instead of lime, and the Carthaginians used mud. Elsewhere there is neither lime nor stone for building, and dwellings are made of roots, osiers and branches, and covered with clay. In other places people make their habitations of wood alone. Herodotus says the Budini make theír buildings of no other material, both public and prívate, as well as temples and the bulwarks of cities and towns.

Pomponius Mela says that the Nerví do not have any kind of timber, or even firewood, in place of which they hum bones. In Egypt they make fue of dung, as ís customary today in many dístricts, especially in the territory of Campos [!fol. 263r], where they bum nothing but cow-dung and straw, and heat their kilns with it.

Thereby it may be seen and understood that sorne people have different things from others, and each of us works accordíng to what he has available. Like in sorne parts of Egypt, the king's palaces are made of rushes, and in the East Indies, the framework of the houses is made of the rib-bones of whales. In the city of Cary in Arabia the walls, includíng the city ramparts, are made of rock-salt. But I think we have dealt with this subject, when I say that very seldom are all the things necessary for buildings to be found, since nowhere is everything so abundant that there is no need to avail oneself of other places, be it for stone, timber, sand or bricks.

What is allotted to the world varíes, and various kinds of buildings are made, each employing what is found in the place where he dwells; we must know how to accommodate ourselves to the material and also how to arrange them skilfully and carefully in the right places, as befíts hard-working and intelligent men.

In Italy may be found a species of black sand, which in theír language ís called pozzolana18, which mixed with lime makes a material as strong as stone once it is dry [!fol. 263v]. It may be used like stone and wonderfully strong floors are made of it. When a building is demolished, they take out these floors in pieces; and lay them together with a little of the same material for the joins, and it comes out as a single piece. So anything can be made of this mixture, big pieces too, like ashlars, which may be used instead of stone where there is a shortage. Buildings are made of it, and it does not deteriorate at all, as stone normally does, which is consumed by itself in the work. So if there is need, this sand and lime can be used in place of stone for making cornices and other things of that type. This species of sand is found at Rome, Naples, and other places in ltaly; someone told me that he had seen it here in Spain, in Aragon, but he did not remember where, but he knew it well.

They make another kind of material resembling lime. It is a stone and is bumt like lime. This substance is gypsum19• But its manufacture differs from that of the lime, differing in the kiln, and the lining it with stone, and the roasting and the 18 'in Italy may be found a species of sand ... called pozzolana' ... understandably there is less said here of this invaluable material, which set under water and could be so handy for docks and moles, than is to be found in Italian authors, from Vitruvius on.

19 'this substance ís gypsum' ... gypsum ís treated more fully here than dsewhere, although the distant sources (Cyprus, Thebes, Syria) are taken from Pliny (HN XXXVI.182), via Alberti. Gypsum, a hydrated calcium sulphate, ís sddom found in anything like a pure state, which ís why our text recogníses so many varieties. As wíth lime, a calcination process in .rhe kiln .removed ~uch of the water content. lt is here proposed that gypsum makes a good floormg and m foundauons to keep the structure dry and hard, as well as for plastering walls and ceilings.

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reduction. This gypsum stone is ash-grey for the most part, although sorne is white, and of various colours. It is roasted with much less fire than mortar, over twenty four hours. After roasting, it is taken from the kiln, and made into small pieces. [!fol. 264r] Sorne grind it up, and others pound it with pestles. Those who grind it do not do so in a flour-mill, but with a roller, like the one for crushing olives. Sorne say that in Cyprus and Thebes it is extracted from caves, already roasted, like what ís said to be dug up in París, but the species of gypsum stones are different from the gypsums extracted ready roasted from mines, and also gypsum is very different from limestone, since it is very soft and crumbles when rubbed with the hand.

There is a kind of gypsum in Syria however which is very hard.

Gypsum comes in different varieties and colours. As I say, it is not roasted in the same way as lime, and is not ready until the smoke comes up all white out of the kiln, wíthout any trace of black. A gypsum kiln roasts in twelve hours, as I said, in eighteen, or at most twenty-four, while a lime kiln needs three or even four days befo re it is burnt. There is a gypsum that resembles warts, and is very white before roasting. There is another kind that is transparent, and the colour of Oriental crystal, which when touched by light shines with great brilliance. An excellent gypsum is made of this stone, but it ís not found in any great quantity.

Another kind is fashioned like an onion with many layers, one upon another, ash-grey in colour. [!fol. 264v] There is a black stone of this same structure, whose gypsum when roasted is quite white.

Another kind has veins of different colours through it, and is very hard. Another one is red; but certainly, this variety is inferior, as its gypsum has too high a proportion of earth. Another stone comes mixed with sand and is marvellous for any edifice and very firm in the work. Any píece of carving may be worked in it, however delicate it may be. There is another stone which splits along the veins like alum. The gypsum made of thís stone is very white, but its height is at most no thícker than a jeme; it comes in sheets like the ashlars in a wall. There is another species which breaks up into thin leaves, and is transparent like specular stone, or selenite. A very good white gypsum is made of alabaster. Of tale too is gypsum made, although very little; and indeed of countless kinds of stone. One species of stone from which it is made curls into veins, like a twisted skein of yarn. It has so many turns and twists, in so many different ways that it would need a long time to explain, as long as the litany. If gypsum is roasted too much, ít goes limy again, and takes longer to set, and wears the hands of those who work it. Gypsum which has once been laid in the work, and then roasted over again, ís wonderful for foundations and where there is damp, [!fol. 265r] for it prevents it getting in, acquiring a certain hardness like stone. This twice-baked gypsum is excellent for making floors, because it never crumbles, nor fractures, nor lets moisture penetrate.

It takes a long time setting, but after it has set, it comes out like iron, so that nobody could dríve a nail into a floor made of it.

Alabaster is sawn in thin boards like wood20; these are used in place of glass windows, since they let in plenty of light. The boards are worked with the same tools used with wood. You may paint anything on them well, and they take well any colours laid on them. This alabaster stone is very tender, and water damages it 20

'alabaster is sawn in thin boards' ... Alabaster is in fact justa fine-grained and compact form of gypsum, usually white or yellow. Being translucent it was frequently used before glass panes could be made in sufficient quantities; and alabaster windows survive in sorne early medieval buildings.

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badly, so if rain falls on it, it becomes stained and streaky, but if it is smeared with oil, it keeps out the water and gives much more light. Alabaster is not found in banks like other stones, but occurs in clods separare from one another within the earth. It has one feature, that if fire touches it however little there may be, thereupon it rurns to gypsum. After gypsum has been roasted it should be ground and made into powder and sifted, in order to apply it in the work: after sifting, it should be made up gradually, not like mortar which after making up should be left with the water for sorne days; gypsum on the contrary should be applied straightaway. And it must be made up in little portions with water, for if it is prepared in great quantity, it will barden and be good for nothing, as it would be impossible to apply it with the hands. But mortar is a different matter, for after it has been slaked, it is piled up and laid in a clamp place, (Illustration 321) anda little sand spread over it, to keep it fresh [!fol. 265v].

Iltustration 321

Kiln for gypsum, prepared wĂźh stone Kiln prepared with mud Pick Iron crowbar Iron mallet Wedge Basket tray Wedge Mattock Float Basket Narrow mattock Pick with heavy back Fork to stir the kiln

All these tools and other things are necessary to extract the stone from the mountain, and make the kiln, and roast and crush the stone, until it is reduced to powder, as it must be in order to be usable in the work.

(lllustration 322) [!fol. 266r] These tools and rollers and the restare what is needed to sift the gypsum, mix it and carry it to the men who work it.

There is a gypsum so strong as to be unworkable: it cracks and goes to pieces, or it breaks up altogether, and can not be handled in any way, unless it be mixed with a fourth part of sand, otherwise it is quite intractable, even if it be made as liquid as water. Then it sets, and nothing can be done with it because of its sparseness, but with sand it can conveniently be applied to walls with the hands.

And there is another variety of gypsum which can not be worked if it is not mixed with a half of earth, but with that mixture it is very strong and the work secure.

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Illustration 322

Roller to grind the gypsum Roller to grind gypsum Basin. Basket for gypsum Scraper Pannier Bucket Gypsum sifter Basin for making up gypsum Sieve Wooden shovel

.'

We should deal now with the use of earth for brickwork and tiles 21 , for buildings, for the work made of brick needs no finishing; walls made of brick are very pretty to see, and very strong and are preserved better than stone ones. Brick is much more resistant in matters of fortífication and city rampares, which are going to be beaten by artillery, which makes less impact on brick and does less damage because when a cannonball touches stone, it breaks in pieces, whereas brick does not even jump, but is only ground into itself.

The method of making bricks consists entirely in finding good earth, [!fol. 266v] which is required to be of a kind of whitish clay: but another kind, of reddish earth is also highly praised, as is what they call sagallon, and potter's clay. I have seen an earth which is somewhat sandy, of which very good, light and strong bricks are made, even though many write that bricks ought not to be made of sandy earth, saying that bricks made of such earth are worthless, because they break when laid in the work, and break a lot when handled. But I have seen also earth which contained no sand at all, yet very inferior bricks were made of it. The earth wants to be very fatty in itself, in order to make quite marvellous bricks. Miry earth is good for making excellent bricks, very light and durable. Above all, one ought to avoid making bricks of earth that has stones embedded in it. That is the very worst variety for this purpose, because it curls in the baking. In addition, when the bricks are baked, the stone is roasted and turns to lime. So when these bricks are wetted, they go to pieces, because the lime swells.

21 'we should now deal with the use of earth for brickwork and tiles' ... bricks come last here, without the priority accorded them by Vitruvius and Alberti, who is nevertheless the main authority for the opening passage- he agaín is the T, while our author inserts again the odd reference, e.g. to the Spanish clay 'sagallon'.

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At what season earth should be dug /or making bricks) and at what season bricks should be worked and baked Earth which is to be made into bricks should be dug in the autwnn, [!fol. 267r] an d left thus all the winter, in arder to mature in the cold, frost, rain, air and sun.

So let no-ene suppose that it is good to work the earth into bricks just after it has been dug up: it has to be seasoned, to make good brickwork, and has to macerate right through. Brick-making should begin at the commencement of spring, but if it should be necessary to do it in winter, it is quite certain that they will freeze, and so will all crack or even crumble away; and the same thing will happen at the height of summer, for as they dry out, they will crack on the surface by reason of the great heat. But if chance should bring it about, that it is quite necessary to make them then, let it be done in this manner; when they are made, keep covering them with very dry sand, and if they be made in the heat of surnmer, cover them with clamp straw, and with these devices or solutions they are wonderfully preserved from cracking or warping.

There are sorne who are of the opinion that bricks should be glazed at the sides, for making the front walls of houses; that means one side only, the part which goes to make the front or facing of the wall. The bricks ought to be made of good earth, which is neither lean nor too fatty, nor too dry, because they would absorb the glazing. I say that the best earth for this, is ene that is somewhat whitish, fat, and of sorne toughness. Bricks for glazing should be made thin, because they bake better than thicker enes. Certainly I have seen bricks one palm thick, [!fol. 267v] and nearly three palms in length; they were like the smallest ashlars of quarried stone. If by chance, there should be occasion to make bricks very thick, they must be pierced with an iron tool, so as to bake better and dry better than they would without the hales, because the steam and heat escape through them when they start to burn. Those whose practice it is to glaze their bricks customarily bathe them in white clay, in arder that afterwards the glaze may coat them more evenly.

And the same thing would be profitable in the manufacture too. I have looked at the buildings of the ancients, and I saw that they used to mix in a little sand, especially of the red sort. And I also found that they used to mix in red ochre, and powdered marble too.

I have observed that from the same earth sorne bricks are made better than others; because, taking clay, and kneading it, and working it like dough, wonderful bricks may be made, and very strong, because after manipulating the clay, it becomes very tough and tenacious, and in this way no small stones are left in it.

On baking they become much stronger and more durable. That is because of the great flame which converts the clay to stone, and indeed makes it even stronger than stone. Since we have spoken of stone being worked like wood, and of countless other stones which are very tender, so these bricks go on top: now whether the fue is the cause, or the drying out, or the air, we see the same thing happens with bread. [!fol. 268r] For when made thin they will have plenty of crust, and thereby will be much stronger although they have less material.

And in addition, if they are smoothed over, the better will they be, and the longer time they will last. And we see the same with stones which are polished, or shaped by polishing, they keep out the weather better, are not consumed by nitre nor by scaling n or by corrosion.

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Sorne are of the opínion that once bricks are baked they ought to be polished a second time, by grinding them after they are taken from the kiln, befare they have been wetted, or dried, because then they become much stronger, whereas íf they are wetted, and afterwards dríed, and then wetted again, they spoil the edge of the tools with which they are worked. But they grind much better when they are raw, and polish better.

The ancients had three kinds of brick. One was three palms of a vara long, and half a vara wide and half a palm thick. The second was five eighths of a vara each way, but one eighth deep. The third kind was half a vara each way. So these two types of brick were perfect squares. I have seen in works of the ancients bricks of two and a half palms in length and two palms in width; an d I have seen different kinds of bricks, which the ancients were accustomed to lay in their works, although these first three were commoner than the rest. [!fol. 268v] Sorne bricks I have seen were not more than one palm long, a quarter of a palm wide, and the same deep.

I have seen another type that were only one thumb thick, a little more than a palm long, and three quarters of a palm wide. So the ancients used clifferent forms in their works, according to the needs of the job, just as is normally done today. The ancients did not use in public buildings what they did in prívate ones, which were normally smaller. And I have carefully paid attention to the house walls of the ancients, although indeed there were many kinds of them, sorne with larger bricks, sorne with smaller. If they made them so variable, it is to be believed that each one would ain1 at discovering how his work might be more beautíful, and the more they did so, the greater the benefit. And so it is to be supposed, that it was not like nowadays, when all follow the one path, and nobody tries to find out how his work may be more ingenious. I have seen bricks that were only half a palm long and three fingers wide, which were used for floors, and besides, laid sideways, herring-bone style, or in the manner of an ear of wheat.

Bricks are to be highly praised that are made in triangles22 , which are very convenient for laying in the work. The method of making these bricks is as follows: a large brick is made, half a vara each side, nearly four fingers thick, and after it is made, and still fresh, it is cut diagonally, [/fol. 269r] so that of one they make four equal triangles. They look very well when laid in the work, because all are equal in the wall, and they bind together wonderfully. allustration 323) Bricks laid herring-bone, in the fashion of an ear of barley, are used for the floors of underground apartments for the summer. There are bricks for this purpose which are not more than four fingers long, two thick and two wide. allustration 324) There is another kind which are one palm long, three fingers wide and one thick: these brícks are used for floors too. The ancients used to use raw unbaked adobes over wood 23 • [!fol. 269v] This type ofbrick is much used in Spain. They are two palms long, one wide and four fingers thick; and of this · material many walls and buildings have been made, of mud-walls alone, without any other mixture. This invention continues to this day, both of adobes and of mud-walls. And I believe for certain that it was left us by the Moors, when they carne to Spain, by reason that we see that all the buildings which the Romans made, 22 'bricks ... made in triangles' ... from Alberti, as is the upper part of the diagram. The au.thor's cornments begin immediately below.

23 'the ancients used to use raw unbaked adobes' ... it is indeed a plausible assumption that adobes were introduced to Spain by the Moors, and then became a typical mode of popular buildings.

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Illustration 323 Bricks which are equal throughout the wall

throughout Spain, are a1l made of stone, including the ramparts of cities. It appears that after the Moors carne to Spain, they made many ramparts of towns out of earth alone, and thereby it may be understood that it was they who brought them to Spain. Today it may be observed that in the towns which they inhabit, the houses are covered with earth ínstead of tiles. That is because in Barbary there is not enough firewood to fue the kilns for baking bricks and tiles.

Iltustration 324

The ancíents used three kinds of bricks24 as we saíd, which were the most common, and which were employed by the Greek architects. One type they called didoron, which were two palms wide and four long; another they called tetradoron, which was four palms wide and long; the third they called pentadoron, each side being five palms. Vitruvius, discussing this subject of bricks, says that after being made, in the raw state, they are not dry for two years and ought not to be baked until this time is up; [!fol. 270r] and they are much better dried in the shade than in the sun.

The earths which were famed among the ancients for thisV: Samian earth was highly praísed, as was Aretine, Modenese, and Spanish and Seguntine, and 24 'the ancients used three kinds of bricks' ... here the author went directly to Vitruvius (ll.3.3), the names, as he notes, being Greek.

2' Pliny (HN X.XXV.160) provides this information; Alberti omits the reference to Maxilua and Callet, towns «in Further Spain» (mentioned in this context also by Vitruvius (Il.3.4)), where these

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Volume IV Pergamene earth in Asia. And thís not making bricks before it is time, may be understood of tiles also. But the best earth for riles was that of Massa and ealento here in Spain, whích Pliny mentions; for after baking, the riles of these towns were of a material so light that they were like wood and floated on the water: so wonderful buildings were made of these bricks. So then, bricks and tiles should be made of the best earths that can be found.

Tiles are made in three kinds: the first are common to all manner of nations, the second is confined to many towns where they are placed in towers and buildings glazed in various colours, as white, blue, green, yellow, tawny, black; and different works are carried out with these colours. These tiles are shaped like tongues, as are those we sha:ll sketch here; where (Illustration 325) A is to attach it; of this there is another kind, as illustrated here Itlttstration 325 A below. (Illustration 326) [!fol. 270v] e D are tiles, although others call them by other names, according to the locality, and they are glazed in di.fferent colours as I said. The other riles E F are rectangular, three palms long and almost two wide.

They are made a little narrower at one end than the other, side G being three fingers high. Temples and houses are covered with them. They may be glazed if desired, or indeed employed without glazing. With common tiles there is nothing to discuss, as they are so well-known to the common people; of these too I have seen sorne glazed, like the others.

I!lttstration 326

Of bricks, different shapes may be made, both for walls and for floors of rooms, to make patterns in them. allustration 327) Figure A is a hexagon with six triangles all round; so that if a floor is made of these bricks, even though they are unbaked, as they are made of two colours, the triangles may be of a different colour, either deep redor yellow, [!fol. 271r] which willlook very well, on account of the variation. And if they are glazed in two colours only, they will be much prettier than with minute decoratíons. And likewise the figure e D can be made on the same principie, varying the desígn of extended floating bricks were made. Identification is uncertain; Masa is the name of a district north of Burgos, while Callet may take its name from a Roman site, near Seville, now called El Coronil. The author has given them a somewhat more Spanish form.

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Illustration 327

l>

hexagons, while if they were made of minute work, they would be worthless, because the interstices or outlines would fill with dirt: bricks must be smooth, even if they have minute decorations. (Illustration 328) Many patterns can be made, as I have said, and many devices of glazed bricks for floors. Those marked M will be of one colour, and N of another, and so it will keep varying; and the same with bricks: [!fol. 271v] R, S and Tare to be of three colours in the form of rhombs, justas Illustration 328

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Il/ustration 329

i

--· - --4- --·-1

j··

M N are. The figure O is an octagon with a right quadrangle, whose parts are of different colours, at least three. This is a very ancient thing, as we will see in Holy Scripture, for the great-grandchildren of Noah began the rnaking of thern for the Tower of Babylon, although there are sorne historians who say brícks were already being used before the Flood, and, as they write, already existed in the time of the prophet Enoch. (lllustration 329) Brkks are made in d.ifferent ways, like objects rnoulded in patterns, as each rnan chooses to shape them; they rnay be rnade in any forrn , triangles, squares, parallelograms, pentagons, hexagons, octagons, spherical, rhombs, and various others, according to what one likes to imagine. Sorne are rnade white and glazed, others are of different colours, the blue made with zaffer, [!fol. 272r] others again with alurn that turns them green, others with antimony or litharge that turn them yellow, and the white ones are with burnt lead. Then, they rnay colour them with ochre, which also turns them yellow, with burnt ochre, and verrnilion, and coundess other colours. Sorne glazed bricks are shaped in rnoulds, so as to make figures of them; and earthenware figures are also rnade coloured with the colours fired, as I said. Bricks are rnade for streets too, I mean to pave thern, and then they are laid sideways; said bricks are one palm thkk, and two long, in order to last much better, and they do not wear so quickly as the others.

Bricks used for covering houses are sometimes flat, fashioned like a tongue, with a dowel at the top to fasten one over the other, as A goes over B. (Illustration 330) Tiles which are made curved like a gutter, are three palms long and are wider at one end than the other. This is done in order that they may mesh with one Il/ustration 330

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Jltustration 331

~.~ ·.~ another; [!fol. 272v] other tiles are flat and have on the two sides two ridges, two fingers high, and they too are narrower at one end than the other, in arder to mesh.

The ancients called tiles 'imbricis' and these others, both the gutter type and the tongued type, they called 'imbre'. They made walls of both these kinds.

Very many works are made of bricks, and the ancients likewise made coundess works of them. Pliny says that they made the ramparts of their cities with compasses, and ensured that they were perpendicular; which ramparts are very fine and durable.

Of this same material they made Royal Falaces and many, many temples, which have lasted to this day: and many tombs and coundess buildings which may now be found to be made of this baked earth material. Bricks and glazed tiles then are of great antiquity, as are coundess other things made of little bricks painted in fired colours, to decorate summer rooms because of their freshness, for they look frosted on account of the lustre of the glaze: allustratíon 331) [!fol. 273r] and that represents the glitter of the ice. Bricks can be made quite differently, for sorne people have a big covered cart, with four wheels, which goes over the clay. It is eight palms long, and five high and six wide. The same man who moulds the bricks, lays them on the working floor, and pushes the cart. And when it reaches the end, he turns the cart round, and keeps filling the fl.oor, and so he gradually proceeds beginning at one end and finishing at the other, but only one brick is done at a time.

The men who bake bricks construct two kilns joined together back to back, and light them both at once, and by this device save much fuel. The makers of bricks work in three ways. Sorne work on a stone bench at the end of the floor.

Here he has his kneaded mud, and makes his bricks, and he has a helper to carry them along the floor; and with this invention makes his bricks and tiles.

The second way is, he keeps laying piles of clay on a floor, and takes his mould and makes his bricks on the ground, bit by bit; and he also has sorne piles of very Illustration 332 For a street, laid sideways up. One and 3/4 palms long, for walls.

For floors, on boards.

For the firm floors of rooms.

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dry sand on the floor, wíth which he keeps the mould working. The third way is for the man who is making the bricks to carry the clay, the water, the sand and the moulds on the cart.

It seems to me that on this subject of tiles, I have been a little lengthy, as the way they are made is such a well-known business, [!fol. 273v] but there is always advice to gíve in these matters, however obvious they may be. (lllustration 332) I have set down here clifferent measurements for bricks, both of ancients and of moderns, of Spain as of Italy.

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EIGHTEENTH BOOK Introduction Stone bridges A full account of all the techniques used in the construction of bridges, displaying sorne of the main types starting with the simplest, according to usual practice here, now follows the book on building materials, which was supposedly justified by their place in engineering projects. In fact these are all arch bridges, based on a tradition that goes back to the great days of the Roman empire. Curiously enough, Vitruvius did not think to devote a chapter to bridges- the more surprising since bridges were and are among the most impressive remains of the Empire. A few, indeed, still stand and can be crossed to this day. One of the most elegant and ambitious is in Spain, at Alcantara on the T agus. It does not earn so much as a brief mention here, but then it was far to the west of the author's field of operation.

Alberti, however, does deal with arch bridges (IV.6), just after bis stab ata reconstruction of Caesar's bridge, and echoes of his exposition can be found in our text.

During the last decades of the sixteenth century work was undertaken on several great bridges, amid an enthusiasm to build once more in Roman style and on Roman scale: the Ponte Santa Trinita at Florencé, the Rialto bridge at Venice and the Pont Neuf at París are the best known. Siting the bridge and specially the placing and number of arches was the first thing to consider, but the main task was the construction of the piers which had to stand in the river. The arches themselves are taken here to be semicircular, as nearly all Roman arches were.

Much of the 'libro' is taken up with building the piers, therefore, and with the cofferdams within which they could be founded and built up. Piers were not only the hardest part of the job, but the most vulnerable, subject to continua! scour erosion, at its worst in time of flood. The cofferdams could be made with poles, or as sheet piling, with planks morticed into the main posts; either the ground could then be filled, or the pier be built from the bed- ideally bed rock- up. While the cofferdams are in use, they are to be protected by temporary cutwaters. In the discussion of the cutwaters of the piers, something is owed to Alberti, who also compares them to the prow and stern of a ship.

But neither Alberti nor any other contemporary provides these .sections through a bridge to show the design of the deck, any more than they try to establish the ideal [509]

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angle of the ramp leading up to it. Clearly the author is trying to bring out the value of geometry in all the details of the structure. He then gives a range of simple bridges, one observed somewhere in ltaly, that displays all the features of neo-classical omament dear to contemporary taste (380r). The three peculiar little bridges which exploit rocks and islets in the stream and go round corners do seem to have caught the author's fancy more than the more convencional type.

As ever, the author can not resist digressions. Water has to be removed from the cofferdam, so that allows another reprise of simple, ancient water-raising devices; tympanum, suction pump, and Archimedean screw are here joined by a grab to lift out the mud.

Otherwise this tapie had already been well treated in Books 13 and 15. After bis bridges, the author decides to go back to the early stages of construction, with more information on scrapers and dredging equipment to clear mud and silt from the cofferdam, and transport it to a place where it can be dumped. At this point, he announces that no account of building operations would be complete without a description of the machine needed to lift materials. So (again, not for the fírst time) we are told all about «the crane, sheerlegs, and winch», along with the two devices used to attach stones so they can be raised, nippers and lewis. That leads him to think about elementary machine theory, to analyse how such devíces work; this is probably derived ultimately from the pseudo-Arístotelian 'Mechanical Problems'. The law of the lever is entangled with observation of the acceleration of falling bodies, which suggests to him that bodies are actually heavier or lighter in according to their position.

Suddenly the book changes tack again, to present what the author sees as bis bridge building masterpiece, a big bridge whose central section can be drawn back to let ships pass through. Here the central arch lacks a keystone, and about 20° of are at the top. Instead the voussoirs are so designed that they should lock together, each compressing the one below, and also holding the one above to prevent it slipping off; they do need iron clamps to keep them in place as well. Then a wooden drawbridge or better still a sliding platform can be cantilevered out over the top of the broken arch, on guides that will allow ít to be withdrawn, so ships can make their way between the middle piers of the bridge. It was, as he claims, unprecedented, and no such bridge was built over the Guadalquivir at Seville, Spain's chíef port for the Americas, at that time.

The details are shown in beautiful exactness, from the clamps to the swivelling brackets which help to support the platform when extended, but there is no general picture to show how the whole would look. Although the mechanísm proposed to move the platform somewhat resembles those in Ramelli's siege engines (Plates 140-5), these mobile bridges were only intended to cross a moat; this is truly a grand design to span a major river ...

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Book on how to make the piers of stone bridges in diverse ways

hen stone bridges are to be made, the order should be given as to how they are to be constructed, how many archings are to be allotted, what manner of piers there ought to be, and how the sides, approaches, vaults and arches are to be calculated; how it is to be paved over, and what difference there is to be between sides and piers. For the differences, that the ends should be very robust, on a grand scale, not only because they have to support the weight of the arches which are a load upon them in the way that the piers support them; but it is also necessary that they be very firm, in order to resist and support the two ends of the bridge, and exert force against the weight of the arches, which are pushing and loading them all the time. So no part has so much work as this.

W

In order to build a stone bridge, a search should be made along the banks of the river, on both sides, for a good site that will have good banks and sides, and a good ground- and if sites can be found of rock, so much the better, provided that such rock should be of good stone, and not be eaten away by themselves. For certainly if it is of good rock, they will be much better, [/fol. 360v] as the whole pondus or weight of the bridge is to be entrusted to it. Allotting the piers, making many of them or few, lĂ­es in the choice of whoever is building them- and also according to the width of the river.

The arches ought always to be made an odd number, the contrary of the piers which always go in evens, to have the arches odd, as 3, 5, 7 or 9 ... and so on; first, because they look better, second, to give the bridge greater security and stability throughout the work, and also to avoid the main current of the river, because if the piers are an even number, none will ever come in the middle of the stream.

The further the current is from the banks, the more swiftly and rapidly does the water flow.

Always make the middle arch of the bridge larger than any of the others, because usually the objects which the water brings clown with it are in mid-stream, and seldom along the banks. Another reason is, that it is much more difficult to found piers in mid-stream than near the bank. And the third reason is that usually rivers are much deeper in the middle than elsewhere. So for all these reasons one must not found in the middle: the less the water strikes the piers, the less damage they will receive from the regular strain which the water lays on them as it strikes. [!fol. 361r] Piers must always be put in those places where the water is more [511]

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Volume IV gentle, and has less current and is slower in its passage. The indications for this can be obtained from the lessons of its floods and freshets. But even when they do not occur, it may be known another way: do like those who help the besieged with nuts, as an indication that their fríends are helping them with things to eat, and so they go and pick them. That is what we shall do; we shall go up stream a great distance, as much as one thousand five hundred paces, especially when the ríver has risen, and the water will be raging. Then we shall throw in sorne objects to float on the ríver, and we shall keep looking along the river downstream, to see where many of these floating objects collect together. That will serve to let us know that there the water is at its greatest fury. Care must be taken to shun that spot when siting or founding the piers; and we shall choose another, where we see that the things we threw in the river collect less, and are more scattered, and also go more slowly; that is a good sign for founding our piers.

But befare proceeding, we should deal wíth the method to be employed in excavating the foundations of the piers, and the solutions to be adopted to make it possible. For it is necessary to look for sorne remedy that will keep the water out of the place where it is required to lay the foundations. In order to begin making the division, the whole width of the ríver should be taken, from one bank to the other; once that quantity is known, it should be divided in conformity with the archings that are required, [!fol. 361v] to see how many fall in that amount of space, and how many piers are needed, reckoning that the arch in the centre must always be a fourth part wider than the others. Havíng seen how many piers fall in the space you have measured, stakes should be driven in where the middle of each pier is going to go, drawíng a cord where it is illustrated on the piers; which will be done in this way, having dríven in the stakes or other markers, as íf it were done by chance, like those illustrated here, with the followíng letters: Illustration 333 Pier

A

~~. ~~

»

e

.~. B

11.

.r·tv

:Jt"f+J

l>

'1 ~ pt.....J

(Illustration 333) and having driven in stakes A B C D. The one in the bank must always be driven in first, and afterwards the one in the water, and the same on the other side; then draw a cord which has marked on it the distance from pier to pier.

Having the two arches at both sides you have also the one in the centre. Then four more will be driven in, where it is marked 1, 2, 3, 4, so asto find the centre of each pier. If there be more arches, you must proceed in the same order, because the water can not be marked out like a floor.

The method to be employed for keeping out the water and diverting it in arder to excavate the foundations of the piers, is like this: after having marked out the · centre of each pier, {/fol. 362r] as has been said, then a much greater space must be taken, as much again as what the pier is going to occupy, both in width and in length, so that the foundatíon will be much bigger than the pier. In addition, it is necessary to leave a space between the foundatíon of the píer and that of the cofferdam, for the greater stability of the cofferdam which deflects the water, and after that the space occupied by the piling; it is better to have one vara's space too [512]

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much than be even one finger short.

To mark out the space which the pier occupies, use the same device of the line that crosses the river.

And let the piers allustration 334) make right angles with the line of the current, in such a way that when those two curved lines are made, as demonstrated in the figure, E and F, that is A B, where they intersect- drawing a line through the two intersections, they make right angles, and likewise G H, which make four right angles at I, as may be seen by means of the figure.

Itlustration 334

1

The whole of the space which is to be occupied by the dam should be staked out to deflect the water. The stakes should not be very thick, and they should be sharpened at one end, so they can be driven home- or even have their tips scorched in the fue because in this way they can be driven home much better.

They are to be driven in very dose together in two rows, at least five palms in width between them and then planks are to be laid lengthways, to join thern well together. Then fill in the space between the two rows of piles with dry earth, for as the earth is heavy of itself, it goes to the bottom. [!fol. 362v] Gangways are to be fitted so beasts can go in and out, to bring the earth. As for the stakes they should be carried out in the summer, when the water is very low, and bears no freshets. Matting made of esparto grass, cattail, rushes or reed mace can be used, so as not to consume so many planks, or in case there is no timber to be found.

(Illustratt"on 335) It may be done another way: let square piles be driven in, with grooves on two sides, not wider than the thickness of an edge of plank, and three fingers deep. The piles are driven in tenor twelve palms apart, and with this procedure the whole space which it has been decided to take in, is surrounded with the two rows of piles, with their channels or grooves, from top to bottom.

Then in the grooves lay planks two fingers thick. They should be well [!fol. 363r] Iltustration 335 Pier raised on bed filled with earth

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cemented on the sides to keep them straight, and well joined together so that no water can get in; and so lay one upon another, reaching from the base to the highest part of the stake.

After the gap between the two rows of boards and piles has been filled with earth, there should be stays or props at the letters ABe DE, (Illustration 336) in order that the pressure of the weight of water may not make the whole structure collapse inwards while the earth is being extracted or the water being removed.

For thís reason the structure should be propped up on the inside, with the timbers which are lettered. In addition to these stays, during the operation, others should be placed lower clown, to make the whole structure more secure. While the water is being pumped out of this space, it will seep through in many places, so sorne Illustration 336 A pier to be founded within this space

seaweed, or rushes or reed mace or esparto grass should be kept ready to caulk them- [!fol. 363v] although the earth which ís laid between the boards should be tamped clown as is done with mud-walls, when it is at the height of the surface of the boards. With this method, the earth is well compressed. After doing this, defences should be made, in order that the spates or freshets of the river can not get into the enclosure, which protection should be made in the following manner, as sketched here. (lllustration 337) A framework of planks should be made, shaped like saw-teeth and raised at the back, with channels to let the water out, when it comes in from the spate.

All these channels come together to form two, which pour the water back into the river, atA B. This device is somewhat restricted; for the same functíon this other one, e D, is more to the purpose, [!fol. 364r] atlustration 338) although it will be enough for anyone to see the invention; and thereby something else of greater ingenuity can be imagined. This machine should be fixed firmly. It is made like a guillochin1, although not precisely in that form. The channels are atA B e D, 1

'made like a guillochin' ... a very obscure word, possibly referring to a carpenter's plane.

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Illustration 337

Channels Channels

placed on a frame to support them in the air. Once this protection has been made, within the enclosure where the pier is to be erected, many instruments for drawing water should be installed- it may be with pumps, or the tympanum wheel, or the screw or snail, or one of the coundess other instruments there are. And many people should be set to work to raise the water, in arder not to stop either by day or by night, because the water will keep seeping in.

Illustration 338

The pump is in the form I will sketch here. The rod L has play at D, (Illustration 339) and should be long enough to reach the water. That piece of wood E has four grooves round it, and then it has a cow's leather round it, and a leather on top, which is only fixed in the centre by the rod L. And this plunger goes inside the cylinder F at I. The cylinder has two pieces, hollowed out to the measure of G; and is to have a few iron bands ro keep it compressed; and in the part K there should be a few little boles, exactly a finger long, so that the water can enter the pump. So, by raising and lowering the rod e, which has play at B, the pump works. The head has a perforated iron sheet, with play at D, which is to have a few hales to control the plunger L, [!fol. 364v] to raise or lower it if need be. (Illustration 340) The tympanum wheel has the same function of raising water, but does not raise it very high, since it takes it in at and pours it out at D through those hales.

For this wheel has two sides made in section, as illustrated at B, and these are all

e

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Volurne IV Illurtration 339

D·

H.

1

A

fastened to the axle A. The handle or crank E is held firm on two stands F and G. This wheel is to rest on a wooden base, in the water. Two or four men can operate it, according to whether it is large or small. A trough must be installed to receive the water and discharge it at H. Or the screw of Pythagoras could be installed; this instrument raises a good quantity of water, but not very high.

Its axle should be as many fingers thick as it is palms high, and the part which has to raise the water as much again. Let us suppose that the machine is 20 palms high; the core or axle has to be twenty fingers thick, and just as much for the bore, which is ten on each side. This screw is made in the following form; it can be made in two ways, not in the form that is, but in the construction. A very thick log can be taken, and given eight sides, and a channel is hollowed out, winding round like a snail; but there ought not to be more than four channels in the octave, because the other four eighths are left clear, to give it stability. [/fol. 365r] Mter making the channels, boards should be taken and all the eighths covered over, and the joins Illurtration 340

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I/lustration 341

well coated with pítch, and íron rings put on from top to bottom. When thís machine is fíníshed, it should be erected so as to make a tríangle of the form A. Bis the second method of a screw or snail. allustration 341) In the screw B as well, I díd not want to demonstrate more than one tum of the screw-threads that rnake the channels, so as not to confuse the judgement or the understandíng.

In the screw rnarked A, it is illustrated how you make squares all along the wood: then begin at one comer and cut all the squares diagonally across right to the end; and in thís way you will achíeve what you desire. If it seems dífficult to lay the boards on the screw A, take cow's leather well-tallowed, and lay it over that.

To get out the congealed mud frorn inside the enclosure where the pier is to be built. The instrument which I shall illustrate here is quite wonderful for that purpose. It fills and empties by ítself, and works like a purse. A shows it closed, B from the open interior; C open from the outside. The instrument is provided with iron plates, [!fol. 365v] (Illustration 342) which have play at the edges of the small square in the centre; and each square has a ring or collar to suspend it from rapes.

In the srnall centre square there is a large ring, with a very thick rope fastened to it, which raises and lowers it. And in the four there are to be four pieces, which are fastened to one rope.

In lowering this instrument, care should be taken to hold the rope that has the four pieces of rope fastened to it, so that when it is pulled only the rope in Illustration 342

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Volume IV the middle goes slack, and the instrument or purse will descend open; and drawing on the middle rope, it will close by itself. And nothing that it will bring up inside in the middle when it closes can fall out at all. When they want it to open, they draw the rope with the four pieces, and it then empties. All the points should be capped with iron plates, with an iron tip at the end, so that it will sink into the mire or sludge as it goes down.

It should not have play on the scoops where it has the numbers 1, 2, 3, 4there it should be very firm. Those hinges go down to the ends of the triangular points in order to have the force to draw up the sludge.

Many other instruments can be installed for this same purpose of extracting sludge. A wheel can be used todo it; [!fol. 366r] a dredge can be used, which will remove a great quantity of sludge. It is enough here to mention it, for we shall deal with these instruments in another place, and give a demonstration with figures.

After the water has been emptied and the sludge removed, then the foundation of the pier must be dug, until you reach a very firm and secure ground. And after this is done, before anything of the foundation is laid, round the excavation drive in a row of stakes which have been singed or scorched, of such timber as may be preserved in the earth without decaying. When all has been filled with theseand this is to be done when a firm ground is not found- then fill it with stakes throughout, as in foundation A of the pier. After the earth is staked, they should be le& over a palm above the ground bed: then fill in from the beginning between the pile-heads with stone and lime, welllaid. When there is a good bed, it will only be necessary to drive in round it, as in B, and then begin to lay the ashlars, very large and of good stone, solid and hard (Illustratz'on 343) so as to resist the great weight which is to be loaded upon it.

Illustration 343

I have studied the works of the ancient architects, and have seen that for the bridges which we have of them, they made a foundation so large that it reached from one side of the river to the other, [!fol. 366v] where all the piers of the bridge were erected on that base, whĂ­ch could not be made all at one time; but should be made piecemeal, and thus little by little all is joined together, since trying to make it all at one swoop would be impossible- save if it were made on dry land, but it would be impossible in the water. So by making it on dry land, or diverting the river, it could well be done very easily. This invention of a base is a very noble and perpetua! affair, and there will be no fear of it ever failing. If one has to make such [518]

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a base, it should be made somewhat higher at the back than at the front, in order to reduce the force of the water, and avoid harm to the base at the front. To have the greatest perfection, this difference in height between back and front should be four palms.

To give asure rule for founding this base would be very unsure, because of the variation in grounds, and also in size of rivers. It is best left to the good judgement of the engineer because one ground might be found very loose, another muddy, another entirely sandy, another of rock, yet another of excellent earth. So it has to be left to the decision of the engineer, to his judgement and intelligence.

There must be one universal rule here: the depth of the pier shall always be half of its length. If the site should give you the convenience of doing so, the foundation should be so deep that if the pier be forty long, it will b e twenty, or more, but not less. Although this rule is universal, it is tme that it will be more or less in sorne places, depending on the grounds and disposition of the locality, and of the ríver where it is to be built. I have here set clown this demonstration of the base, lengthways and sideways.

Lengthways is A. The piers are B. [!fol. 367r) Where there are numbers C is the sideways one. The numbers go in tens, so that the whole base is 60 wide and 20 high, as they show. The height of the cutwaters is 20, in conformity with the height of the base. It also shows the cant of the base at the back. (lllustration 344) Illustration 344 Foundaúon which crosses the whole of the river

A

Trying to make a foundaúon to pass from one side of a ríver to the other, is a matter of great expense, and not the work for a single town- ir would daunt an entire kingdom that had to undertake it, and if the river were big, it would frighten a King. It is quite certainly not possible for human wits to look for a way to stop a whole river from passing in its usual track, in order to build in it For I find neither instruments nor artífice that will be enough to stop a river altogether, although stopping sorne part of it is a thing that can be done with much convenience and

skill. lt is true that it is not a business for everybody, since it demands much imagination, besides practice. So if one has to work in the like business, the least possible area of the river should be occupied, and never make an impediment to stop the water, larger than one pier with its base and foundation. [!fol. 367v) It will be done in this way: if each pier be ten feet in width, let its base be twenty in depth for the foundation over which the pier is to be erected.

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The piers are to be made in the shape of ships, with prow and stern. The prow is the part whĂ­ch lĂ­es towards the current, and the stern is the rear part, as the water flows. Both prow and stern should have obtuse angles, and in no case acute ones, since they would then break in collisions with the objects which the river brings clown with it when in spate. These cutwaters are placed before and behind the piers as defences; they are to be stream-lined2 so that collisions should do less damage to the cutwaters- for so the populace call them- in order that the water should set up less resistance in the piers, and that as it divides its effect should be diminished by the obtuse angles, which does not happen with acute ones because the obtuse angle causes a greater deflection of the water than the acute. I leave aside many other inconveniences that they have, since the acute angles break much more easily at the least impact, whereas the obtuse takes no harm, however forceful the collision.

There are other piers, made another way, without angles at the ends, but having semi-circles at both ends, which resist more securely any collision or impact which may strike them, rather indeed the force of the water reinforces them, because of their circular shape. That is made very plain to us, seeing that behind the piers eddies form in the water, [!fol. 368r] which are by some called revolutions, and also much more water accumulates at the stern than at the prow. These eddies cause great damage to the stern or rear part of the piers, because they keep digging out the river bed in such a way that they usually undermine the piers in the lower part, to their innermost foundations, and hence we see that most bridges fail at the stern, not at the prows of their piers. For there we usually see them very firm and never failing, rather indeed we see that the river reinforces them, and loads them and packs them with sand brought clown with the water. As we see that that is so, the whole structure must needs be very robust in every part, so it can resist in the conflict it continually has with the river, which does not cease attacking the piers night and day. It will be then necessary and convenient too, for such structures to have very good foundations on all sides, particularly the lower part of the stern.

These names are quite appropriate, since it has more the shape of a ship than anything else, being a thing of water. Returning to the subject, it is necessary to reinforce that part of the stern, much of which might be consumed or worn away by an accident caused by the water, or by the passage of time- I mean the stern of the foundation. Even though a great part of it might be consumed, [!fol. 368v] yet what remained would be enough to support the piers- although they might eventually fail by reason of the very great weight upon them.

This warning will be valuable: more than anything else do not start by erecting the piers at the river's greatest depth, because usually, when it passes over that part, it does not look as if the water is going to fall to any great depth, but rather, passes over it as if it were gliding and slipping along. When the engineer finds the sort of place he wants for his foundation, he will be extremely content, and in great hope that the work will be durable. If we find sorne part of the river bed raised more than the rest, that will put us in great heart, expecting the structure to endure, since the river could never flatten that section out nor remove it. And any fall in the water must be avoided, since it is wearing away the bed on which it drops, all 2 'they are to be stream-lined' ... 'al hilo de la agua', literally 'in the thread of the water', exposĂ­ng the least surface to erosion.

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the time, and begins digging it out, whether it be sand or earth, and then carries it off little by little, and in this manner undermines the piers at those points.

At the beginning, when founding the piers, the stones should be very large, in height, width and length, and the larger they are, the better it will be for the work.

Keep it in mind that they are to be very strong and of a very solid material. And let them be such as can resist any klnd of foul weather that time can bring, such as ice, sun, air, and great freshets of the water and spates of the river. I have seen in many places where there were corrosions of nitre, [!fol. 369r] others were cracked by ice, and breaks were caused by the great heat of the sun and the force of the air which struck them; and no less because of the spates of rivers, in such a way that every wetting is an accident which makes them crumble into fragments- just like a certain kind of stone, which breaks into fragments when fire touches it. And the cause of all this is the great beating they take from water, air, sun and ice. There is another species of stone, which does not crack, but gets riddled with boles and eaten by its own self. There are others, which decay and are gnawed away, others which are very feeble, and when the weight of a load is laid upon them, they go to pieces. So the engineer should be a prudent man, one who knows how to discern which stones are best and recognise their quality and their effects. Then after the work is done, he will not regret having laid such stones in the work- and in truth he would have much to regret if he were not able to cure very easily the many disasters which could result from his carelessness or ignorance.

When the work is begun, there is need to apply great care to working the stones and laying them alike, in every part: let neither the layer nor the dresser lay a stone without the prudent engineer passing an eye over it first. And every stone that will be laid, should be laid with the level, rule, and plumb-line; keep checking with a long ruler that all the stones are laid even.

[!fol. 369v] Take care too that no stone lies lengthwise, nor any joint, for they should be laid crosswise, and the joins transposed as I illustrate here. Although somebody might say that (Illustration 345) this is superfluous, because every Illustration 345

r .1 apprentice knows how necessary it is to link the stones in this way, yet I have seen the work of a man who boasted of knowing architecture very well, where I noĂşced this striking flaw in his construcĂşon. Leaving that aside, when the stone ashlars of the foundation are laid, they should be tied together with leaded iron hooks, their iron bolts also leaded, or lined with sorne other metal, in order that rust may not consume them. The whole foundation is to be tied this way inside and outside until it is above the water. In such an important building any scrimping should be avoided; be liberal with money, because the smallest accidental defect would waste more than all the lead and iron spent in a construction of this character. So the ashlars have to be tied both inside and out. (Illustration 346)

[!fol. 370r] Certainly, I have seen in Ancient works a very good and inexpensive tie; it was made of pieces of holm-oak, shaped like a dove tail and inserted in both [.521]

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ashlars. In the centre a peg of the same wood had been driven, which then entered the upper ashlar, as illustrated here. (Illustratt'on 347) So far as can be understood, it surely must be more than a thousand years since the ancient work that I saw had been erected, and these dove tails were as good as the day they had been made. That is quite a marvellous invention, and costs little; it is both firm and durable. That peg went three fingers into the ashlar, and three more into the upper one: the tails were two fingers thick and half a foot long. So that a good craftsman bound his work well in this way, and with little labour tied bis ashlars with this invention. They could be made of iron as well as wood, nor would it be necessary to lead them.

But if they were to be made of iron, then they would have to be a good inch in thickness, one palm long, three fingers wide in the middle, and an extra three at the ends. But this tie is to be understood as referring to above the water only. If you wanted to make these tails or hooks of metal, bronze or latten, [!fol. 370v] they should be made like those of iron. If they should happen to be required to be of iron, then after they have been made, to prevent water and lime from rusting them, put them in wax and pitch as if you wanted to temper them; atlustration 348) then you need have no fear of their rusting very much, or even a little. Metal ones can be made fairly thin because of the expense, and also because they are not consumed by water, lime or earth. The hooks are commonly made in this form. Both kinds are to be laid in the stone in such a manner that they are wholly inserted in the ashlars, and do not project above them in the slightest.

The work Ă­s to be raĂ­sed evenly on both sides, that is from one end of the pier to the other, and raised very high for fear of the river flooding. The piers will be made in width one quarter of the bridge's height: it should be understood that means taking from the right abutment of the arch to the whole height of the arch, then divide the rise into four parts, and one of them will be the width which the pier is to have. Let us suppose an arch eighty feet in height from its abutment, eight divided into four comes out at twenty for the width of the pier. So the pier is to be eighty feet long from prow to stern, of which the two cutwaters take half and the remainder is left for the width of the bridge, [!fol. 371r] as is illustrated in the figure A, the width being B. There have been architects who have made the prow and stern rounded, as in C. (Illustratt'on 349) Illustratio1: 347

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This pier B has right angles at each end, both at the prow and at the sternthese angles are quite sultable for splitting the water. (Illustration 350)

Illustration 348

This next pier D has acute angles, which break easily, and are far worse.

(Illustration 351) Pier E has obtuse angles, which are more robust, and have greater resistance than any other kind of angle for any kind of work whatsoever that may be requlred.

Ido not mean of water, but also for artillery. [!fol. 371v] Since the bulwark made with obtuse angles resists the impact of artillery much better, how much more will it resist water, which acts with less violence (Illustration 352) Illustration 349

Pier G has a round stern, and prow the same, and is a body that resists better any impact that may befall; indeed, the more it is struck, the stronger it becomes.

(Illustration 353) I like those Ancient craftsmen too, who made their piers without angles, just as if they did not know that it had to have so much force. They made the ends blunt and rounded; they did not leave them obtuse, but so formed as to allow them reasonable corners, which would be three quarters of the rectangular Illustration 350

Illustration 351

Illustration 352

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Jliustration 353 80 feet long

square3- and if that did not seem right they gave them two thirds of the appropriate square. A is the three quarters, B the two thirds of the square, as can well be seen in the following illustration.

Jtiustration 354

[!fol. 372r] (Illustration 354) If such a site were to be found that was exactly what we might desire for building a bridge, if B A Nature were to provide it for us, it would then not be necessary to make piers on both sides. But when the like arrangement is not to be found, we should make two piers- one at each side- in the ground, with their cutwaters, as described above, like the piers that are to be built in the water. When any bridge is made sorne arches should be made on dry land, as we shall illustrate below, because time and the spates of the river consume and ruin the banks as they eat them away and demolish them on account of their great floods. Space should be left to enter the bridge, and for the safety of the sides, by making the bridge much longer than the width of the river, and by leaving a path free for the water to go through the bridge.

The vaults of the arches should be very strong, to withstand the great thundering of carts over them, so they can endure the wear which they receive continually from passing carts, from animals and other weights that regularly turn up to cross by the bridge, like artillery, colossal statues, obelisks, and many other things.

Bridge A is made leve!, and all its arches increase toward the centre. The middle arch is sixty feet, so its pier is to be the sixth part, and that is the least that can be allowed; [/fol. 372v] the two arches at the sides are fifty feet each, the next two forty, and the two in the ground thirty, although all the piers are made to ~me pattern, and to the same measure. (Illustratz'on 355) Bridge B is divided up in this way, but has those Httle arches 4 , one third of the big ones. This is done so as not to employ so much material. It is much stronger, and the weight does not press clown on the piers so much. For that reason I have set it clown by way of illustration. Only they ought to be enclosed by a simple wall.

1bis one I saw in a bridge in Italy.

Bridge C is quite different from the other two. It has more ingenuity, and greater security, because of its many piers. [!fol. 373r] For it is almost to be supposed or understood that there is a single pier at D, whích has that vent for ' 'three quarters of the rectangular square' ... this strange geometrícal construction perhaps interprets Alberti's advice on suítable angles. In the diagrams, three sides of a superfluous square are shown, the línes on the fourth side show what is meant by two-thirds of a right angle- i.e. 60°and three quarters of a right angle, 67.5".

4 'bridge B ... has those little arches' ... presumably intended to spread the load of the arch and of the upper part of the spandrel. Unfortunately the site of the bridge is not identified. In bridge C the secondary arches built into the piers reduce the proportion of river blocked by piers, and also serve as mill-races. Milis were indeed often erected on brídges. The eyes in the spandrels provide an outlet for surplus water in time of flood; they too were not uncommon in contemporary bridges.

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Jilustration 355

water, between the two piers or cutwaters. These little arches D are made for (Illustration 356) two purposes, one we have already stated, for greater securíty, and the other ís to accommodate buildíngs, graínmills, or fulling-mills, or for polishing arms, or for poundíng gunpowder, and for countless other trades, machines and works.

The two followíng illustrations A and B are sections through the rníddle of the two bridges, although they work in the same way. At A is the thickness of the arch.

B is the parapet of the bridge. C is a bench, to take the sun in wínter and the fresh air in summer. D is where people pass on foot, andE where carts and pack animals go, so that neither carts nor animals can be a nuisance to the pedestrians. For that reason the cart way is at least two palms lower. [!fol. 373v] A surface of gravel, more than one palm thíck, or of thick or heavy sand is poured over the stone paving, so the carts will not trouble the bridge with their continua! traffic; by means of this remedy, the bridge will be much better preserved. (Illustration 357) When sorne very large weight has to pass over the bridge, two very thick beams, equal in height, width and length should be joined together, with sound iron clamps to bind these bearns all round; and they should be nailed down, the clamps should not be more than two palms apart; they are to be one finger thíck Il/ustration 356

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Illustration 357

by two wide. There are to be four of the beams, used in pairs, so that the wheels of the cart which carries the weight will run better. [!fol. 374r] They are to be bevelled, or inclined at the ends, so the wheels can easily mount them. Once it has reached the end, the other two are laid clown, and so it goes by stages until the specialload has crossed. There are drawbridges which no cannon can cross in any way save with these beams as illustrated here below. (!llustration 358) Illustration 358

e

Beams like this can also be used where there is a bad passage, where the ground Ă­s very loose, where the wheels are so stuck that they can not get out except by the force of many animals. With these beams any large weight whatsoever can get ~ through, without leaving a mark in the ground, even where there is heavy mud in winter. The beams are laid parallel to the gauge of the wheels of the gun-carriage.

So there is no doubt that it could pass over any bridge with this invention without sinking into the ground at all.Any kind of ornament can be fitted on bridges: such as cornices, columns, friezes, pedestals, architraves, pediments, figures and various other things, provided they be put in suitable places. Bridges can be covered with roofing, or with other things, like vaults or tracery, all of which can be applied over the whole, to provide benefit and advantage to the bridge and help it to resist [!fol. 374v] the daily stresses which the arches suffer, and to be a cause of greater stability and perpetuity.

Every bridge then should be constructed of very good, firm large stones. That may easily be understood by taking an example from the strokes of blacksmiths: for if the anvil is large and heavy, it can well endure the blows of the hammer, although they are large and heavy too, whereas if it is small and light, it jumps even at slight blows, and moves from side to side. Just the same, I say, it is with arches, they ought to be made with their sp andrels or sides well filled and firm. The strongest of arches is the semi-circular, for none of the other kinds is as strong, or looks so well, or has so much grace as this. Sometimes it is necessary to lose [526]

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sor_nething of the proportion in respect of sorne arches rising so high, through their bemg so large, that they have to be made much lower, because they are bigger than their piers, and rise up vertically. When the floods come the water strikes the arch· and a drawback like that has to be removed. I have seen many bridges with this ' mistake; it is very great ignorance on the part of the engineers who made them. So when there is no such space available, arches should be made in the shape to be seen on the next page. The sides of the arches should be strengthened with excellent stones, as has been said of the foundations of piers. Arch A has been trimmed very little, arch B much more, so that it does not look well. In these arches no thin or narrow stones may be used, [!fol. 375r] without their being in width at least a twelfth part of the span of the arch, so that thirty stones would go into the arch, according to the order of circles- or somewhat more than that quantity. The arch is C. (lllustration 359) Itlustratt"on 359

Trimmed arch

Trimmed arch

We have dealt with bridges and piers in the preceding material with all possible subtlety, but, appreciating that the subject may not be so easy for every artisan to understand, it will be well if I enlarge on it a little, espedally on what concems piers.

The span of the arch of the bridge must not be made wider than six times the thickness of its pier; that is all that can be taken from piers. Nor can piers endure being made thinner than a sixth part of the span of the arch, nor thicker than a quarter of the span of the arch that is to actas a load upon it. Now let us say that the arch has a span of si.xty, then the sixth part of that is ten, which would be the width of the pier; and that would be to make itas narrow as can be [!fol. 375v].

And if we were to take the same sixty, and make four parts of them, which is the greatest width that can be allowed to the pier, that comes out at fifteen. So between these two extremes all those means can be taken that run from ten to fifteen. They are to be allotted as you shall see fit, although the best (Illustration 360) proportion is from thirteen to twelve or twelve and a half, and that will always come out truer.

So you can take away from fifte~n and add to ten. But it is to be done with sound judgement and discretion. For if the pier is fifteen, the arch can not be less than sixty.

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Illustration 360

+

1~

-· AJl the ashlars are worked on a plan, of a guide rule or bevel5 . The keystone of the arch ought to be somewhat more in the upper part than any of the other stones, as it closes the arch, and is placed outside so asto do so properly. It may even be necessary to make it go in forcibly, pushing it in with a few blows of a mallet (of wood so the stone does not break), and driving it home forcibly so as to compress the remainder of the arch, [!fol. 376r] for if well compressed the stones will stay very firmly in their places, and do their duty very well. The space between one arch and the next ought to be filled in with stone, in such a way that all is very firm, indeed nothing should be firmer in the whole work. If by chance, through a shortage of stone, or the need to save it, you have to make the work much more secure, you may do it in the manner which I illustrate here. (Illustration 361) Illustratíon 361

Il/ustratio1t 362

Stone is saved under arch B, which is formed by A and C, in the comer between them, and expense can be saved, as well as much stone, lime, and even time, because that little arch B has great strength towards the two large arches. If there should be sorne soft, loose stone, it could be placed in the sides of the little arch, towards the arches A and C, above B: and thus something will be put into the work which seems to serve no purpose but really that little arch is of great value in that position. But I say no more on this subject, having dealt with it in another place.

Now let us discuss the ramps of bridges, because very seldom do we see bridges coming so level with the ground that there is no need to go up to them. I have seen ' 'a plan of a guide rule or bevel' ... 'planta de un cíntrel o barbe!' ... a 'cintrel' was a centring rule or line; a 'barbe!' was like a builder's square, but with one side curved. Both were used to ensure that the voussoirs were aligned smoothly.

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Illustration 363

....,

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countless bridges, and in almost a1l you had to go up, [!fol. 376v] and in sorne. the ascent was difficult and quite dangerous. T o show the method of ramps, I have set clown sorne here, so it may be possible to recognise which are dangerous, which flat, and why on every bridge the upper side should (Illustration 362) be level, so as to be a straight line, like on timber bridges. Certain it is that you will nowhere find a convenient place to correspond to that line or height, and usually ramps will have to be made. For a concealed ramp, such that the roadway does not appear, it may be made in this manner; the beginning should be taken well back, for every four feet allow one of rise- that will be comfortable for laden animals to go up, and also for carts and other weights. But it seems to me that it would be more convenient (Illustration 363) to allow one foot of rise for every eight, because laden pack beasts can then go up with less trouble. When making streets, they have to be raised, to discharge the rain-water, so for every thirty palms one should be allowed, of fall or rise; that is a point which is almost unrecognised, and yet it is advantageous. This ascent and descent can be fitted into very short spaces. Long stones must then be laid, [!fol. 377r] to serve almost instead of steps, in order to retain the pavement, since a1l these ramps have to be paved. I must admire them much more when they are adapted to their position. I believe that any artisan whatsoever will be able to look after himself in his works much more conveniently with this advice. I wanted to employ a mean between (Illustration 364) thirty and fifteen, so as to use the difference; this ramp is neither steep nor fl.at, as the figure shows. (Illustration 365) Illustration 364

e 1

o

Bridges drawn upwards are ordinarily so made that the outer part lifts, so that no-one can reach the gate, for fear of falling under the open part of the bridge.

These bridges are usually made at the gates of cities and castles where there is water- and even where there is not any, if only there is a moat, and it is a deep one.

The stones for paving bridges are to be wedge-shaped like fists, and a1l between the arches is to be made level, like fl.agstones, although it would be better to pave them with river stones, so that the pack animals will not fall when they cross, nor keep slipping and sliding about, through the surface becoming smooth on account of the continua! movement over it.

A parapet ought to be raised, passing right along the bridge, from one end to the other, made of flagstones or other long stones with leaded iron clamps, Illustration 365

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{/fol. 377v] so that none can fall off into the river, or make others fall. The stones with which bridges or streets are to be paved ought not to be too round, because they would not lie well. To lie better they must be flat- that type is the best, the most highly esteemed and they carry out our purpose best, because the round ones will come out at the least impact. The stones must not be too small either, but like the palm of the hand so animals can more easily walk over them. Carts also make grooves with their wheels, the more so when they go continually over the same place. And animals produce heavy wear on the stones over which they pass. We have even seen ants leave a mark in the hardest stone by continuous movement, when they keep coming and going by the one path. I have seen sorne roads paved by the ancĂ­ents which were full of thin fine gravel or grit in the centre so that cartwheels would wear the roadway less, and animals would have better footing.

The andents held that the best stones for this purpose were pebbles, which are llint stone, or flint silica; or those which have hales, breaks or cracks in them, not because these stones are the hardest, but because animals slip less on them than on others. However we make use of all kinds of stones, according to what we have in abundance. [!fol. 378r] Always select the hardest stones: they should be one palm thick and another wide; keep joining them to one another in the upper part, so they stay even and no empty space is left in the centre of the roadway.

The pavement is to be raised in the centre of the roadway, like the back of a fish, which is higher in the middle than at the sides, so rain-water will run off better; although commonly the opposite is done, making it lower in the centre than at the edges. That is because they want the water to run the length of the roadway. But I say that it is better for it to run off at the sides; so the water should have outlets at intervals in the sides of the bridge. Although there are three methods of paving bridges, they are plainly made lower in the centre, as I have said- that is normal practice when they are broad and long, but when they are narrow and short they are raised in the centre. There is another method with the water running from one end to the other, but that is done more with streets than with bridges.

If I were to deal here with all the different kinds of bridges, it would be a very prolix business. Yet in arder not to irritate the thoughtful engineer by giving only Illustration 366

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Eighteenth Book three bridges, I will make mentĂ­an of sorne very strange ones I have seen, sketching them here: their illustrations are as follows; the first is A, the second B, and the third c.

The first illustration then is of bridge A. It is situated in a ravine between very high cliffs and can not be carried straight across because of its bad position[!fol. 378v] it could not be done any other way. Por a good site and position are a great advantage in construction. But the good judgement of the builder even in such an inconvenient place as this ingeniously took advantage of a rock in the middle of the river, and so gave it that bend, and erected his bridge, putting it up in all its perfection and leaving a model for our over-presumptuous contemporaries. (lllustration 366) Bridge B is of another construction, with different turns. By finding those rocks in the river great expense was saved through not having to lay foundations in the water. Then he made his structure in this shape: it was indeed the inventĂ­on of a very prudent man, very expert at finding the right place among great mountains, Illustration 367

where he found great rugged rocks where he might make his bridge, as it had been entrusted to such a craftsman. Although sorne might say [!fol. 379r] that he only completed his bridge so well because he discovered such a suitable place and material, the truth is that if he had had to found new piers, he would have erected it straight. (Illustration 367) But as it was, he knew how to take advantage and avail himself as much as he could of his sound judgement and intelligence, by choosing the right place and making his structure at less expense and with greater security.

Whereas if he had not done all this, but founded anew in the river he would have had excessive expense, and perhaps it would have been less secure, and his honour and reputation would have run sorne risk.

Bridge C is made in sawtooth fashion. It was a building that caused much trouble because of its being in an inconvenient place, although that location would be a great benefit to the people of the neighbourhood as a short cut. A way was found to make it, as was done with the others. At all events, it proves the intelligence of the prudent b uilder, and we are to be grateful that they have left us [531]

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Il/ustration 368

examples of which we can take advantage. The illustration is as follows {/fol. 379v].

(Illustration 368) There are sorne bridges which are covered over, and even decorated wíth columns, pedestals, and arches, with their architraves, friezes, cornices, and as ornate architecturally as they can be. So I believe ít would not be out of order here to teach the method of making the most elaborate bridges. Here I shall only make an illustration of a single part of a highly decorated bridge, because I think that there will not be room to illustrate the whole, to avoid prolixity, as from what is shown here, you can easily understand the whole construction.

Bridges are all usually made to fit the rivers which they are to cross, as the site requires, {/fol. 380r] and also to match the river floods, which are often very great.

The entry and exit of the bridge have to be level, if possible, and not dangerous, all the piers of any bridge have to have their grillage befare they are settled firmly in the water, as I have said. (Illustration 369) When the foundations for the píers are being dug, if the ground is found not to be suitable, and has no firmness, and is all mud, although we have dealt wíth this subject in the beginning of digging out the foundations of piers- {/fol. 380v] yet the more one considers a subject the more one finds to say and to learn about it.

In such a case great ingenuity must be used so that when all the requisite depth is excavated, and firm ground is not to be found, then in order to build over it, take a large quantity of oak wood- and if there is no oak to be had, take black pine or green holrn oak, and lay all this timber flat, as we shall here demonstrate. Sorne beams form a point, and those which líe toward the current go differently from . those which go at C; the figure demonstrates how they are to be laid. It is the same with those which go at B. That is done so that the ashlars líe across all the beams, because if they went like those which go at e, the ashlar would take it lengthwíse, and would not take up more than one beam, (Illustratz'on 3 70)whereas going this way it takes up two. The illustration of the difference between them is shown here in the two figures. If anyone believes the lower one better than the upper, (lllustration 3 71) he will choose whichever is more to bis purpose.

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Iltustration 369

The trees that are good for this are the oak, the forest pine and the alder, [!fol. 381r] whose wood lasts well in water- indeed any wood that is durable in water v.rill be very good for this purpose, but above all the alder. This tree does not become very thick, it has a leaf like that of hazel, gives no fruit, grows dose to water, and nature has so endowed it that it does not decay in water. When there is none of this wood to be found, the olive is excellent, because it lasts well in the earth and in water without decaying as it is a very oleaginous wood. So the moistness of the water can not penetrate it, but rather turns it green. If timber to be laid happens to be dry, sorne device must needs be used to prevent it decaying, it must be scorched with fire, so as to form a charcoal over the surface. When that is done the timber will be highly resistant to the moistness of the water.

I/lustration 370

A

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As we are dealing with the removal of water from places where it is required to found piers, and also we have touched somewhat on removing mud with that instrument made like a purse, yet because J,· there are countless others, it seems right to e me not to be too brief on this subject. To remove mud from the bed of river or sea, there are many instruments, especially the crowbar scoop, the wheel, the iron grate, which I shall set clown here as my practice is, so that they can be understood more easily than would be the case if the illustration were not shown. An instrument is made of iron or wood, having a base and three sides, but has no side at the front. It is very low and has four feet, [/fol. 381v] to which are fitted four pulleys. This instrument is made like a grille or grid on which is laid a Unen cloth, very thick, like a sack; it is taken to where there is mud or silt, and filled up there, and so they clean up and empty all the mud or silt with it.

The instrument has the following shape: it is like a grid, as I have said, and a sack is placed on it, of sorne very thick material so it may better hold the mud that comes into it. It is moved by dragging it along on those feet turned backwards at A; (Illustratt"on 372) but if you want to use pulleys, that will be up to whoever uses the instrument, for it can be used just as well without them as with them. It is used to clean out a harbour. (lllustration 373) The instrument above, A e, is to extract earth from one place and carry it elsewhere, and it does the same with mud or silt.

It is called harona, or leveller, and there is very little ingenuity in its construction, [!fol. 382r] apart from its being well fastened together with iron straps. The only other thing is an iron plate at letter A, which forces the board up and clown. This plate is to be like a cutting edge. At B there is a slope toward the ground. At D two cords are fastened to drag it along the ground; they are fastened again at E. The rings are for when it is required to be raised, here two cords are fastened in the same manner as at D, and so it is hoisted up and emptied.

e

There is another method of removing mud from river or sea, in which they employ a little barge, taking a straight post and fixing it very firmly at the bows.

And they lay another over this beam to actas a crossbar, like the mast of a ship but slender with free play where it is attached. At the end that goes over the bow, where it enters the water, a board like a kiln-shovel should be fixed to it, three palms or more in length and nearly two in width- like the helm of a skiff or barge.

Illustration 372

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Illustration 373

e

Another srnall barge is laid next to it, which receives the rnud drawn up with the crowbar and laid in a hopper placed in the centre of this other barge. This hopper is to be like the one into which com is poured when it is ground. It has a little gate in the base, opening downwards the whole of its length. Upon this hopper there is to be a wooden shaft with free play, holding a cord which goes clown to the little gate, the shaft being free to take up the cord, and to release it. The rnud is poured into this hopper, [!fol. 382v] which when full is ernptied outside; and so the harbour is cleaned out just like the foundations of a pier are emptied; but as I say, this instrurnent is worth much more for dredging a harbour than for the foundations of a pier. The crowbar scoop is A, B is a plate which grasps the two parts, like in those mud shovels they use for making ditches, I mean for cleaning Gllustratt'on 374) them out. lt has free play on an iron peg C. D is the haft of the shovel. The mud pours into the hopper G which has its windlass E, having at the end the bar F. Its gate is H, with a ring through which goes a cord to open and close it, with play at I as can be understood from the figure of the barges. There is another invention for this, Illustration 374

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which will be set clown wben we deal with harbours, where we shall give instructions on this and other inventions. [!fol. 383r] I think that I ought not to pass in silence over the way that stones are raised and lowered in buildings. The commonest instruments are the crane, the sheerlegs, and winth. Here we shall explain them, in drawings and in words. The winch is an instrument for hoisting weights up, even very large ones, when you know how to equip them with block and tackle, for by doubling the ropes, it will hoist up any weight however great. Nippers are put at the end of the rope, to raise and lower the stone. These nippers are of iron and shaped (Illustration 375) like Illustration 3 75

the letter X. They have this property, that the more (Illustration 376) the rope is pulled, the more they press the object which they are grasping, in the manner shown here below. It may be seen from the figure allustration 377) that those rings are so long that it can be opened as far as may be required, and compressed until they touch the two ends of the nippers A B. The rope is fastened at C, and the nippers come together at D. Illustt'ation 376 This crowbar scoop with this wheel is for cleaning harbours, by pushing forward and backward Illustration 377

In place of the nippers, an instrument called the lewis may be used, which is like a game-pouch. e lt is made of iron, in three pieces, numbered 1, 2, 3.

These three iron members are placed in the stone, in which a hole has been made of the same shape as the lewis. But D and F are put in first, and E last, {/fol. 383v] and then comes the shaft A with that iron peg B, and then its cotter pin C. Under the lewis the numbers denote that the two end pieces D and F are to be wider than the middle, E. This instrument is very safe, much more so than the nippers, because whether they pull on it or leave it slack, it will not move at all, which does not happen with the nippers, which on slackening come away from the stone, although two hales [536]

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Very large weights are raised with the crane, which rnay be directed to any part of the work, without any trouble, because the shaft or rnast has free play on an iron pivot at N. [!fol. 384r] The axle B of wheel A has free play at the two ends, on the two legs C. This axle draws up the crane's rope E, which passes over the pulley H. The crane is so called because of the long neck which extends as the beam K holding the pulley K, and those two stays which support it. Sorne quite large long wooden pegs are inserted to serve as rungs of a ladder. The frame M keeps the foot.of the rnast F upright. This frame has four stays to support it. At the end of the rope, there is a ring, with a hook O. Pis the weight. Others put clown thick wooden boards, which have at Illustration 379 their four corners four iron hoops, with four pieces of rape which are fastened to rape E. This part Q has various names among arúsans.

Let every rnan call it what he wants: for sorne call it the horse6, others the ass, the pack-saddle, the sling of the crane, others heart, like the one on the balance for weighing things.

~

atlustration 379) The sheerlegs is a wooden instrument which has three legs.

Weights are raised by rneans of it, but not very high. These three legs are fastened at the very top toan iron bar, whereby all three have play in rings, on this same bar.

Each leg is capped with iron at the top, where it has a piece of iron like a hook, which goes into the ring. Underneath the bar it has another ring, [!fol. 384v] for suspending a pulley-block to raise weights. A winch is fitted between two of the legs to wind up the rape, and lift the weights, which is done with very little labour.

M is the bar with its rings, the hooks go through the rings A B C. D is the pulley-block, E the one underneath. H is the winch. The spokes are I, the rape G. The winch has play at K. (Illustration 380) These two rings of iron are nailed on. F is the points of the legs, also of iron. The sheerlegs do not carry weights very high: to lift a weight, and then lower it quickly, there is no instrument so apt as the one called the swipe, which has very little ingenuity about it. allustration 381) It is a lag A, driven in upright, open at the top in the shape of a fork, as it is depicted here. When there is nene to be found already forrned in this way, it rnay be so shaped by hand. [!fol. 385r] An iron or wooden peg passes through it at B, where the rod F has play. A weight is attached at C, and also a rope to pull it clown, and to lift the weight E, which is suspended at D so it will go up very quickly, as well as go clown. This device is used by farrners to draw water frorn wells.

In raising water frorn wells, it rnust be known what force will be needed. The more weights are raised, the further they are removed from their place, the heavier 'sorne call it the horse'... simply a board on which material was laid, with rings at the four comers so that they could be hoisted by crane. One of the words, «cevilla», mentioned here reappears as the stretcher with handles so men can carry it. (386 v).

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Illurtration 380

or weightier they become. Being removed from their centre is what causes it. You need then to know how to divide the weight by means of ropes, since it keeps increasing. Let us take for example a weight that is of a thousand pounds, suspended by a rope without having any doubling; it then has a thousand pounds in weight. But if that same rape were doubled, each part would only have to hold five hundred pounds. If the cord made four doublings, each one would hold not more than two hundred and fifty pounds. So the more times the cord is doubled, the less weight each piece holds. A very great weight can then be raised with very thin cords, considering that every one of them can raise so much weight by itself, so that by putting in many blocks, with their cords, the weight is continually reduced. What we are discussing may be understood very easily if we should make an illustration, so that anyone who wanted to take advantage of this idea would have something to thank me for, after all my labour and zeal.

[!fol. 385v] atlustration 382) With these illustrations weights could be imagined of much higher numbers than these three that I have set down by way of example for the thoughtful craftsman.

The moving of weights is carried out by different methods. With stones conveyed for working, although they are a weĂ­ght, there are three methods of moving them; [539]

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Illustration 381

one is by carrying them, the second by pushing them, the third is when they pull them along. If the weight is moved with peles or small beams- they should be long ones, because then they are moved with much less labour and more ease than with a short pole, even though it be one and the same weight or stone- because with a long pole, the further it is removed from the point of application, the lighter it makes the object which is being moved. So, with pole B and pole C: both move the weight A at the same point- I mean in the same place- then B moves it much more quickly than C, [!fol. 386r] with greater lightness and ease. That may be seen very plainly in the movements of objects, specially with things which we convey Illustration 382

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upwards, as it might be drawing sorne weight from a well, the further it is from us, the lighter it is, and the nearer it comes to us, the heavier it becomes. The cause is, that the further weighty objects are from their site and place, the heavier they become, as on the contrary the more weights are lowered, the more velocity and speed they acquire, the less weighty they are and the less impact they make. Yet of two descending weights, of the same material, shape and weight, the one which falls from higher up makes the greater impact. From this what has been stated may be discovered: the higher it is, the heavier. D is the weight moved, (Illustration 383) A the men who move and raise it. Bis the iron bar, C the stone from which the bar Illustration 383

and the man gain force, for without it the weight could not be moved without very hard work. The longer bar B will be, the easier the movement of the object moved.

Illustration 384

G is the weight pushed; E the man who pushes it. But pushing weights [!fol. 386v] demands a certain dexterity more than strength, for they are moved very easily if you know how to walk it in its movement as you push it. Something should always be placed undemeath, however small it may be, because if once the weight lĂ­es flat, it will be very difficult to get it moving, if you should have to push it again.

(Illustration 384) A weight is carried in one of two ways, either upwards or downwards, for we do not deal with the oblique movement any more, since it is a celestial motion. A is the weight, o the stretcher on which it is carried, those who carry it are B and C. (Illustration 385) [!fol. 387r] There are two methods of hauling weights along, one is by hauling them over the ground so they slide along. There is hauling them with animals too, but that form of traction is more like the roen who are carrying the weight A. In case the weight can not be dragged over the ground the wheels keep going, as [541]

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Illustration 385

appears in the figure of the cart; they never stop, but maintain their motion all the time, from where they begin to where they finish up. Therefore it is not carrying but hauling.

The following illustration willlet us understand what it is to see the weight hauled in the proper sense. For the longer the ropes, the less the work is felt; and the shorter they are the heavier it ís. It travels less when the intervening space ís long; when it is short ít travels further, but with more work. atlustration 386)

Here I propose to deal wíth a new kínd of bridge, whích I believe has never been made or seen, or only very rarely. As ít is so new, I think I can say that it ís an invention never understood or ímagined. For an opportunity to make use of it could present itself, and the builder could be so stupid and rash as to decide that a bridge structure like that lacks all order. It happens like that every day when proposals are made in councils and committees to many learned engineers when they find themselves without words to reply, they decide straightaway that by means of the Infinite Goodness [/fol. 387v] human judgement can find a way in all things, even if they are very difficult; so although similar buildings may present themselves- that is no reason to lose heart and hope of completing the enterprise.

I have said new invention, never seen or heard of, since neither Vitruvius, nor Leon Battista7 , nor Sebastian Serlio, nor many others who have written on architecture, such as Antonio L'Abacco, Pietro Cataneo, Jacopo Beroco Vignola, Hieronimo 7 'neither Vitruvius nor Leon Battista' ... ifLeon Battista must mean the Bartoli translation of Alberú (1550), the others were published soon after: the first part of Serlio's 'Architettura' appeared in 1537, but all seven books were not published togeilier untill584. The third book, on anciquities, which carne out in 1540, was cited earlier in our text (II. 196r). Antonio dall' Abacco's 'Libro Appartenente a l'Architettura' was published in 1558, Pietro Cataneo's 'I Quattro Primi Libú di Architettura' in 1554; Giacomo Barozzi da Vignola's 'Le Regole delli Cinque Ordini dell'Archtitettura' in 1562. Maggi's 'Delia Fortificazione delle Citta' (1564) was really a book on

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Maggi, nor countless others, fine rnen, of such rare intelligence have ever rnade rnention of anything like it. But in order that the construction rnay not seern irnpossible, I will do what I can to fi.t rny conception to whornsoever shall pass his eyes over the illustration drawn here with a desire to take advantage of it.

Let us take an exarnple: in the river of Seville a bridge is to be rnade in such a way that the ships which come up the Guadalquivir frorn the Indies must pass under it with their masts up. For this purpose the bridge would have to be so high that even to think about it gives one a feeling of horror and fright, never mind putting it into operation, and so nobody is surprised that it can not be done- or if it were done, it would be sornething enormous, and people would shudder to cross it. But I do not want the bridge to be higher than is normal practice in all bridges.

Nor do I want to deal with any other subject than ships whose passage is through the said bridge. It must be made like the others then, with its arches, the central arch being so wide that a ship can pass through it freely without touching the piers, with a good clearance. The two piers that support this central arch are to be made much thicker than they would need to be for the safety of the bridge, [!fol. 388r] so much so that they themselves have as much perfection and strength as if the bridge carne to an end with them: for the arch is to be open in the middle; it must conform to all the rules given for other bridges. Let this arch have forty palms of empty space through which the ship with its mast, cordage and rigging may pass without any hindrance. If this arch is to be open in the middle, its two parts are to be supported in the air, on both sides, and therein is all the cleverness of the structure. Someone may be wondering how this bridge can be built; the marvellous arrangement of it is given here, the method of making the arch and the placing of the stones, and how they are to lie on one another, so as to be supported by themselves without being held firm anywhere. That will be done by means of the tie which the stones of the divided or broken arch form between themselves. This arch is easier to make than two arches joined together, as it does not have a central pier with the two arches or ends in the air. This invention carne into my mind while I was looking at an ancient arch, the stones of which were made of two kinds of ashlars, voussoirs or wedges. Sorne were like they are in ordinary arches; the other part had more ingenuity, and the stones were made more cleverly. The tie was in the manner illustrated by the letters with numbers.

The stones to be used in such an irnportant building must be very large, firm and good; the bigger the better. The quality and nature of the stones must be understood. And see that it is not loose, but durable and firm, to resist the weight without fracturing, for it is to hold firm against the injuries [!fol. 388v] and weathering of time, like the air, frosts, the heat of the sun; it must not be eaten away by the exhalations of the water and the salt it contains.

Information should be obtained then as to the nature and goodness of the stone, since the skill and diligence of the master would be of little help if the material were poor. You ought to inform yourself also if any of the stone you military engineering and urbanísm, and there were certainly other books on fortífication at the time which could have been mentioned. But none of these architectural authors spends any time on bridges. The one striking omission is Palladio who certainly does offer us a series of brídges (1 Quattro Librí dell' Architettura, 1570). Even he has nothing like this. Does the omissíon indicate that this passage at least was written before 1570, and after 1564? It may be only that the author had left Italy before 1570...

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want to select has been used in similar buildings before, without breaking, or showíng any fault or change, tbereby giving proof of its good quality and nature.

When you are assured of the wortb and goodness of the stones, take out sorne pieces six palms in height- and if they could be larger, they would be so much the better- and let tbem be five in width and four in thíckness, so you can remove these cutbacks on both sides. I find no tie better, nor more clever for a structure than this. Removing those two parts from the stones, the ashlar is left divided into four parts. Remove the two as in ashlar A, (Illustration 387) [/fol. 389r] so it leaves plenty of body for the ashlar: a better kind of ashlar is B, by reason of the square, Iltustration 38 7

Oo "

on which the ashlar líes much better, and lays its load well, because it secures tbe pieces so that they have more strength. This advantage is not obtained from ashlar A, because no ashlar lays its load on it to keep it in an upright position, as it does with ashlar B. (lllustration 388) Leaded iron Iltustrotion 388 bolts are inserted underneath on both sides, where the numbers are, above and below. On ashlar A an iron member is set in the front P, and likewise with the other ashlars, as may be seen all the way along, as in ashlar B, and in the rest, as indicated at I K L M N O. The same will be done at 8 7 6 5 4 3 2 l. The same arrangement atA BCD E F G. Besides their bolts, they should have their clamps, of iron or bronze, as indicated at Q, and in the rest of the stones, as indicated by their letters, so that all are bound to one another. That is enough, for they are kept stable by their own great weight. And so the arch stands, without assistance of anything else to (544]

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hold it [/fol. 389v], as it would if the arch were complete. For then all the ashlars would be tied, as in all complete arches, for they ordinarily have their keystones in the middle of the arch, driven in by the force of a mallet.

But this one has to stay open, to enable a ship to pass through with its mast erect: the space to be left open has to be thirty feet in width so as to let it pass: Across this open part, there is to be a wooden bridge, which can be removed, in and out, any time that a ship needs to pass under the bridge. The arch ís to be very hígh and wide because of the ship 's rigging and mast. Thís drawbrídge ís to have parapets along the sídes; it is not to be understood as a drawbridge like those at the gates of cities or castles; I call this thing a drawbridge as it can be taken away and put back every time it needs to, in such a way that no-one can fall in the water. The clamps inserted in this work are to be broad and thick. That part of them which goes into the stone is to be four fingers long. In this kind of work and structure, which is so important and so advantageous there must be no negligence, with the expenses; on the contrary, any scrimping is to be avoided, use great diligence and liberality; and the builders kept well supplied with iron, lead and all provisions, because that is the key to the structure, what holds it all together. There is to be particular care of the metal, because all the weight and the labour of the work is entrusted to that alone. The braces or clamps are to be wide enough for the lead to take hold and tie well, as also the boles for the clamps and braces, which are to be wider at the base than at the entry, [/fol. 390r] like those made with the crank for lifting stones. The boles are indicated in ashlar Z. They are to be made in their proper form. Those of the ashlars of the arch, that is L M demonstrate the way the iron clamps are to be leaded: it is necessary to lead those of ashlar L first, as it can not be done afterwards, because the lead will not flow upwards, as anyone can see from the example. So, in ashlar M the boles are to be made wider at the pase than at the top, and channels for leading are to be made (Illustratt'on 389)- that is A B. The channel of A will be in the middle of the ashlar, but that of B should be made at the side, because after stone L is laid it can not be leaded through e, so Illustration 389 the lead has to be put in through side D to be cast.

It could indeed be leaded when A is, but then it would not be secure, there would be great consumption of lead, nor would there be any certainty of the clamp staying leaded. Therefore you should go for safety, and have less expense.

[!fol. 390v] I have given this advice, so no-one will be deceived into thinking he can do it after the stone has been laid.

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The method of making this drawbridge so as to close that part of the bridge which has been left open; although it is a little difficult to remove in and out, for which I shall give ínstructions here. Firstly, the method is to be given for how the wooden bridge is supported ín the air, so as not to fall, while supporting a weight on it, and also not to cause an obstruction at the time when ships are passing below, because this device has to be well understood befare we move on. (Illustratz'on 390) I say that very thick iron members are to be made, as thick as can be, on both sides of the bridge. They are to have play in two or three iron rings, as we illustrate here, showing the method by which these iron members support the bridge. Iron A is round from A to I and square from A to B, which is twelve feet in length; [/fol. 391r] and at Ca piece, of iron I mean, and

ll/ustration 391

square too, must project beneath that same member, and enter the bracket D. A square hole is made for the iron C to enter and hold firm the iron D. This iron D is ínserted at N into the round iron I, passing through it from one side to the other, as iron A passes through iron E, and F, and is held firm at G, which has a socket in the centre, in which the poínt of I enters so it can have play in the two upper members. So this ironwork will be made on both sides, three on each side, making six in all. When the ship stops, these assemblies will turn toward the open Illustration 392

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part of the bridge. The wooden bridge (Illustration 391) is to be mounted on beams, and is to be in two pieces, which join in the centre, so there will be less work in removing them in and out. They are fitted in this manner: they are inserted into one another, justas the two pieces N andO are inserted in P Q. So it is with A D and BE G F, [!fol. 391v] where the two pieces atA B e go over one another, so that O can enter at P Q, and so G H I , into those others, K M L. So those two pieces N O go in under the two pieces M I. All these have their iron straps, which cross over the two ends of the beams. There are also iron straps at A B e, nailed clown well, and the same at F. The same thing is to be done with the beams on the other side, where the two pieces N O are fixed, and they too are to have the same iron straps nailed clown in the same manner as A e B D E F In this invention three beams must be used joined together.

Now it will be well for us to deal with the way these two bridges, or two parts of a bridge, are to be set in motion, for they can be raised in many ways. f'irstly, they could have hinges, and the two bridges (Illustration 392) be raised like the drawbridges of cities or castles, with their chains and beams with counterweights.

The hinges would be made very strong and nailed clown well to the wooden bridge, and would have play in strong iron pivots, [!fol. 392r] well fastened to the stone and leaded into it. So they would serve the purpose well. A B e are the leaded ends which enter the stone, and in their rings the other pieces D E F have play. These are fixed to the wooden bridge, and nailed clown well with their iron straps tightly fastened on both sides. In this way the bridge will be adapted for rising. The parapet will fold back over the bridge, in such a way as not to form any obstacle when it is raised. But it should not fold outwards, because the hinges do not form more than half a knot where they are fastened, so they are unable to fold over. As I have said, that is one way.

Illustration 393

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I/lustration 394

The other is very different from the above. This bridge is not raised upward, but only pushed forward and drawn back, when it is required to open. It is to have balls under the beams of the bridge, which travel over a beam fitted upon an iron bar which projects to support the bridge. These beams travel along a groove from one side of the bridge to the other, so that they can not get out of their seat, nor pass further forward than is necessary. It is pushed forward with a lever. The bridge is to be somewhat longer than would just close the gap in the bridge, I mean by the half of the gap. [!fol. 392v] When it is required to be pulled back, two winches are fitted, at the sides, with ropes and a hook which passes through rings attached to the two ends. When the windlass or winch moves, they pull it back as far as it may need to reach. This is the bridge with its members of timber and iron justas they should be, with another just the same on the other side. (Illustration 393) · At S T are the channels through which the balls of the bridge are to travel: at V the bridge is inserted through that groove: [!fol. 393r] at X are the rings where the two cables are attached to pull the bridge back with the two windlasses or winches.

In this way one can pass under and over.

The third method of moving this bridge in and out is Illustration 395 very different from the two which have been descríbed: it is to be done in the manner stated above, but in the movement to and fro there is a clifference as we shall indicate here. (Illustration 394) On the teeth F pulleys are placed8 so that it may travel better over the beam at G. This then is the third method of removing and replacing Bridge D, by moving the pinion which has sorne holes in the axle E by which it is turned- as it turns to one side, the bridge goes forward; and to the other side, it goes back. This invention can be fitted on the upper surface, [!fol. 393v] to the same effect. Many other different inventions can be made to move it to and fro. The axle is E, and the lugs of the cross have rounded edges, as at G. There should be two of these pinions, one on each side of the bridge, as can be understood from the figure. (Illustration 395)

8 'on the teeth F pulleys are placed' ... che fixed wooden teeth are to function as a rack-bar.

P1.11leys are not illustrated; perhaps rollers are meant here, to act as bearings so as to reduce friccion, as in sorne drawings of Francesco di Giorgio and Leonardo da Vind. The 'bolas' of the previous method must be a very early proposal for ball bearings.

[548]

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