VOLUMEill
Illustration 233
The wheels of barge milis are very different from those of all other milis, since they are very broad and hígh, because all other wheels have the water guided to fall upon them vertically, that is from above downward, whereas these have nothing of the sort, just the water flo"l.ving against the boards C. And as it does not fall vertically, it does not have such great force as the water which falls from a height and is tapered by something which keeps it compact, and so exerts its full force. But here the water strikes the wheel at its own sweet will, [!fol. 321v] allustration 233) without having anything that will give it the force to strike with greater impact. As the water movcs in this way, and is so wide, the wheel should be very broad for the river to tum it, so that whatever it does not get in height, may be gained in breadth. These are the reasons why the wheels are made so broad in these barge milis, which anyway do not grind much, because the water has no head, as has been noted. They normally grind ten to twelve cayzes over a day and a night; that is the most they grind, any that do more will have sorne head of water from a sluiceor when the rivers are in spate, then they grind much more than usual. The milis they call of muscle. These milis are adopted where there are no rivers or water to make a mili; and because of this deficiency, the Maker of all things has provided men with intelligence, so they can remedy their human needs, specially in the grinding of corn for man's sustenance. Yet where the element fails, animals make up for it to remedy the lack of water. Muscle milis are usually driven by animals, and that is the reason why they are called so, although in many parts they are called donkey milis. They are for the most part employed in fortresses, although they are customary in many other places too, particularly in Seville. I have been given to understand that in the whole city they do not grind with any other type of mili but these donkey milis, even though I understand that in Sevilie there is a very great river, called Guadalquivir, which passes very close; and I am assured there is no mili on it- I am quite astounded. To make these milis there is more ingenuity than there is in those on rivers, only in these the milistones are much smaller. Although I have previously set clown a muscle mili27 it seems to 'although I have previously set down a muscle mili' ... such mulúple purpose milis o&en appear in the literature, and sorne at least were installed- the astronomer Tycho Brahe had one which was to pulp rags for paper and beat hides for tanning, as well as grinding his grain, so he could mechanise the producúon of bis books. However, they were usually meam to be powered by water or wind, not by one poor donkey. Even in alternate shifts, a single animal could hardly turn the two crown-wheels which drive the polishing wheels and the stamps, just because all were worked from a single shaft. But the mechanics of the day did not appreciate that each task would require an energy input. 17
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fUNDACIÓN
JUANELO TURRIANO