1 A Brief History of Artificial Intelligence
“Artificial intelligence is growing up fast, as are robots whose facial expressions can elicit empathy and make your mirror neurons quiver.”
– Diane Ackerman
“The science of today is the technology of tomorrow”
– Edward Teller
IN 1997, IBM's Deep Blue computer famously defeated world chess champion Garry Kasparov in a six-game match. This event marked a major milestone in the development of AI, as it demonstrated that a machine could outthink a human in a complex game with countless possible moves. The jubilation felt on achieving such a feat was mixed with hand-wringing that the age of machines was about to eclipse the age of humankind. Kasparov himself could not believe a machine could have defeated him and insisted this was a modern version of the Mechanical Turk, a 19th century con where a small person hid inside a supposed automaton and played chess.1,2 Despite these expressions of disbelief, the match captured the world's attention. Chess was, after all, an ancient game highly revered as an expression of human mental ability. This event sparked a new interest in the abilities of machines that could think and adapt and even outshine humans.
Nearly seven decades since the prefix “artificial” was attached to intelligence, we live on the cusp of one of the largest disruptions in human society. When the CEO of Google, Sundar Pichai, calls AI one of humanity's most profound inventions,3 and other tech luminaries such as Bill Gates argue, “The development of AI is as fundamental as the creation of the microprocessor, the personal computer, the Internet, and the mobile phone,”4 and Elon Musk goes so far as to
deem it potentially more dangerous than nuclear weapons,5 it is hard to dismiss the furor around this new technology as hyperbole. We may indeed be living in a time of profound change.
Artificial intelligence's rise and awesome potential have been a topic of discussion among tech insiders for quite some time. Now, with the emergence of ChatGPT, a much greater slice of humanity is witnessing firsthand the impact of this technology in their daily lives. If there are skeptics questioning the impact and abilities of artificial intelligence, their doubts are certainly being challenged.
AI manifests in our lives in the form of self-driving cars, virtual assistants such as Alexa and Siri, and unprecedented information via search engines. It is even more prevalent behind the scenes, powering medical assistants, farming, and disaster response. AI developments are quickly transforming the way we work, communicate, and even think. The invention of the automobile changed landscapes and economies, while radio and telephone transformed communications and society. AI is poised to join these ranks of major disruptors in the coming years. We are witnessing the birth of a transformative force that will change how we make decisions and perceive the world around us.
However, the implications of this technological transformation are not without their challenges. There are concerns over privacy, security, and job displacement. Evidence shows that AI reflects some of society's worst habits, such as racial and societal bias. As AI continues to become more sophisticated and more integral to our lives, individuals and society must carefully consider its ethical implications. With the proper safeguards in place, the undeniable benefits of AI could usher in a new era of progress and prosperity for all.
How Innovators Throughout History Paved the Way for Modern AI: From Babbage to Turing
Artificial intelligence was long the province of fiction, fantasy, folklore, and myth. Inanimate objects developing human-like intelligence and abilities beyond our own are common in the stories we share. From figures such as mystical golems in Jewish tales and
enigmatic homunculi of the Middle Ages to the evil computer HAL in 2001: A Space Odyssey and the iconic droids in Star Wars, these legends reflect our curiosity and desire to create intelligence in our image.
Next, we trace the broad outlines of AI's emergence, from early conceptualizations of universal calculating machines to the first manifestations of what we today call AI.
Charles Babbage
The first practical steps toward AI happened in the last 200 years. Charles Babbage (Figure 1.1) emerged as a seminal figure in the history of AI, revered by many as the progenitor of this field. Babbage, a brilliant mathematician and inventor, possessed an indomitable spirit, a penchant for spectacle, and an insatiable curiosity that led him to his brilliant achievements in computing.6,7 His fascination with automatons mimicking human intelligence was sparked at age eight when his mother whisked him away to a museum of scientific artifacts and wonders. There, he saw an artful creation—a dancer cradling a bird—so exquisitely crafted that it appeared lifelike. From that moment forward, Babbage's destiny was irrevocably entwined with the pursuit of crafting machines capable of emulating human behavior.
Credit: The Illustrated London News / Wikimedia Commans / Public Domain.
In his late 20s in the early 1800s, Babbage designed the first
Figure 1.1 Drawing of Charles Babbage
mechanical computer, the Difference Engine. This groundbreaking machine could perform complex mathematical calculations, such as producing tables of logarithms.8,9 Indulging his showman tendencies, Babbage delighted in donning extravagant attire as he showcased his creation to the venerable Royal Society in London and other esteemed venues across England. Tales of his eccentricities, ranging from chasing musicians away from his abode when they impinged on his concentration to his fastidious craftsmanship, where gears and tools personally ground by him remained in use long after his death, embellished the legend of this extraordinary man.
The Difference Engine was never completed during Babbage's lifetime. It wasn't until the 1990s that it was finally built according to Babbage's design. It is on display at the London Science Museum, and a second one remains in the possession of a private donor who financed its creation.
Although Babbage was not able to see his design take life, it inspired his later, more audacious creation, the Analytical Engine. This was a much more ambitious endeavor, surpassing the Difference Engine in its versatility. Babbage intended it to be a general-purpose computing machine that could be instructed to perform any type of calculation. He envisioned tables of mathematical values being formulated, and these tables of values would inform calculations of things like dates of eclipses. Crucially, the Analytical Engine encompassed the fundamental duality of modern computers: the ability to store and process vast troves of data.
Regrettably, quarrels with his engineers and the drying up of funding meant that the Analytical Engine, like the earlier Difference Engine, was never built. It nevertheless stands as a major milestone in the history of computing. It was the first machine designed to be truly programmable. And it also helped to popularize the idea of artificial intelligence.
Now recognized as the world's first computer programmer, Ada Lovelace (Figure 1.2) collaborated with Charles Babbage on his prototypes. When recounting the history of science and technology,
Ada Lovelace
the contributions of women have often been overlooked or underrepresented. But Ada Lovelace, daughter of the romantic poet Lord Byron and Anne Isabelle Milbanke, left her mark as indelibly as any male pioneer. Despite being born in the 19th century, when women's opportunities were limited, Ada Lovelace defied societal norms and fervently pursued her passion for mathematics and science. Her mother was responsible in large part for Ada's education. Seeking to shelter Ada from her father's perceived and infamous instabilities, she ensured Ada got a firm grounding in logic and mathematics.10
Figure 1.2 Ada Lovelace, watercolor painting, possibly by Alfred Edward Chalon in 1840
Credit: Science Museum Group / Wikimedia Commans / Public Domain.
When she was 17, Ada Lovelace met Charles Babbage at the house of Mary Sommerfield, a Scottish scientist and mathematician. Sommerfield had recognized a keen scientific intelligence in Lovelace and consciously brought about this intellectual match. Lovelace and Babbage became collaborators.
Her insight into Babbage's Analytical Engine went beyond his own ideas. She envisioned its potential beyond mere calculation. She
recognized that the Analytical Engine could be used for more than just crunching numbers; it could be a tool for creativity and generating complex outputs. Her notes included an algorithm for calculating Bernoulli numbers, which is widely regarded as the world's first computer program. This visionary insight earned her the title of the world's first computer programmer. Unfortunately, like many bright intelligences, she succumbed to her body's infirmities at age 36. But her legacy in computer science guides researchers and engineers to this day.11
John von Neumann
John von Neumann (Figure 1.3) is another of the most prominent people to lay the foundations of computer science. Hailing from Budapest, Hungary, von Neumann was a child prodigy, a versatile intellectual who hungered for mathematics and physics. His unconventional, multidisciplinary approach to studying made many skeptical of his seriousness, and, like his predecessor Charles Babbage, he gained a reputation as a maverick.12
Credit: Los Alamos National Laboratory / Wikimedia Commans / Public Domain.
Figure 1.3 John von Neumann
Von Neumann's extraordinary intellect carried him to doctorates in chemical engineering at the University of Zurich and mathematics from the University of Prague. When he submitted his doctoral dissertation to the faculty at the University of Zurich, the professors found it so profound and complex that they couldn't fully understand it. They asked him to simplify it, but with characteristic conviction, he firmly declined. To his mind, if they failed to comprehend the magnitude of his ideas, they lacked the qualification to pass judgment upon them. As a result, his dissertation remained unfinished and was never formally submitted, yet it still significantly impacted the field of mathematics and was later published as a monograph.13
Von Neumann moved on to the University of Berlin, where he continued to baffle his peers and students. Many stories of his time there illustrate his brilliance. Once, a student in a statistics lecture asked him a challenging question about a complex mathematical calculation. Without skipping a beat, von Neumann proceeded to solve the problem mentally and provided the answer within seconds. His lectures were often marked by brilliant expositions, which the students would then spend hours deciphering amongst themselves. In the 1930s, he landed a teaching appointment at Princeton University. There, his genius would shine most brilliantly, and his pioneering contributions would forever transform the field of computing. Today, we take for granted the CPU as the brain of a computer and memory where computer programs are stored. Von Neumann was the genius who formulated these concepts and helped make them a reality, like UNIVAC, one of the first computers ever built.14
Alan Turing
For decades, the Turing test was held up as the holy grail of computing and artificial intelligence. It was an answer to the question of how we would know when machines had become intelligent. Mathematician Alan Turing (Figure 1.4) proposed his eponymous test, though he called it the Imitation Game.15,16 The test consists of questions posed to the machine and humans. If the
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squamous, yellowish, sticky covering, under which the psoroptes lie hidden and which affords them nourishment.
The crusts steadily grow thicker and lift the individual fibres of wool, tearing them from their follicles, so that patches of skin become bare. The patches thus formed increase in diameter, for the acari leave the centre, where crust-formation is replaced by abundant desquamation of the epidermis. The skin is thickened, assumes the character of parchment, and in old-standing cases becomes wrinkled.
The disease always commences along the back, withers, loins, and the upper part of the quarters. Thence it spreads to the flanks and sides of the chest. The psoroptes are almost exclusively confined to recently affected points on the edges of the scabby patches. They are visible to the naked eye, and appear as little whitish-brown points.
Scab is specially liable to attack a flock containing lambs and yearling sheep, whose skin is thin, fine and supple, and therefore more susceptible to their attacks. If a portion of a scabby flock be shorn, the shorn animals will probably recover on account of the psoroptes transferring themselves to the animals with long fleeces.
The diagnosis is easy. Psoroptic mange cannot be mistaken for sarcoptic mange, on account of the different points affected.
Psoroptic mange only attacks regions covered by wool, and sarcoptic mange those free of wool. A microscopical examination of acari removed from the diseased animals will, however, immediately remove all doubt.
Nor can the disease be confounded with phthiriasis, the trichodectes being immediately distinguished from the psoroptes by their greater size and the shape of their head. Moreover, they are usually to be found on the front portions of the shoulders.
It is more likely to be mistaken for another disease, termed by some writers seborrhœa and studied and described by Delafond under the name of sebaceous folliculitis. This disease appears mostly in autumn, and attacks animals much exposed to the weather and on moist, cold soils. It begins with very violent pruritus, followed by biting and loss of portions of the fleece. The skin is red, inflamed and painful, and the wounds are covered with large quantities of yellowish acid discharge of a sticky and offensive nature. The
treatment of this disease consists in placing the sheep in clean, dry, well-ventilated sheds. Recovery is assisted by clipping and the application of some emollient dressing to the diseased parts.
The ease with which the disease can be cured and the absence of parasites enable one to readily distinguish it from psoroptic mange (scab).
Prognosis. The disease is not specially grave, so long as only a few animals are affected, for it is not difficult to cure by isolation, good feeding, and proper external treatment; but if scab appears in a flock, the freedom with which the animals intermingle is such that all are rapidly attacked, and the irritation produced at once checks their growth and causes loss in condition. Many ewes give birth to small, feeble lambs, which are almost certain to die, and in any case the wool is considerably diminished in value.
Delafond estimated that psoroptic mange formerly attacked one thirty-fifth of all the sheep in France every year, causing damage to the extent of five francs per head. At the present time, and since proper sanitary laws have been instituted, it has become much less common.
During the bad season of the year the mortality is greater, and may reach as much as from 40 to 50 per cent. In cases where scab is accompanied by some other disease, such as distomatosis, it may even rise to 80 per cent.
The treatment is preventive and curative. Preventive treatment consists in separating the healthy from the diseased animals and in disinfecting the folds, sheds, etc.
Curative treatment. The first point in this treatment consists in improving the diseased animal’s food both as to quality and quantity.
It is to be observed that the parasite has more difficulty in living on robust and well-nourished animals. Moreover, observation shows that transference from poor land to rich pastures is sometimes in itself sufficient to bring about a spontaneous cure. Such, at least, is the belief of the Spanish sheep farmers in Estramadura and of the French shepherds.
The shepherd can do a great deal to arrest the course of the disease. If he is careful, zealous, intelligent and observant he will
quickly note the first indications of the disease and, by isolating the animals, check its spread.
The second point consists in shearing the diseased animals, and this must be carried out at any season of the year. The money loss is sometimes important, but must be met, for otherwise treatment is impossible. In cases of localised scab, empyreumatic oil, oil of cade, solutions of sulphuret of potassium, decoctions of black hellebore (water 1 quart, fresh rhizome 4 ounces or dry rhizome 2 ounces), decoction of tobacco and diluted tobacco juice (6 ounces in 1 quart of water) have been recommended. Such local treatment, however, is often useless, because incomplete.
When scab is generalised and it is impossible to define the parts attacked, general treatment is indispensable and the diseased sheep should be dipped.
As a preliminary, however, and in order to make sure that the application will produce its effect, the animals after shearing should be passed, twenty-four hours before the medicinal bath, through a warm bath containing soap in order to soften and remove the scabs. Applications of oil or some fatty substance will also soften the scabs, which may afterwards be removed with a scraper without producing bleeding. One pound of soft soap may be dissolved in fifty quarts of water and each sheep plunged into this and scrubbed with a brush for a few minutes. Washing alone removes a large number of the parasites.
Whatever bath be used it should not be given until four or five hours after the last feeding. The dips most popular in France are as follows:—
Tessier’s Bath (1810).
For 100 sheep Arsenious acid 1½ parts or lbs. Sulphate of iron
„
The above materials should be boiled for ten minutes, and, as a consequence of the chemical fusion which occurs in the process, the proportion of arsenious acid dissolved amounts to about 2 drachms per quart instead of 3¾ drachms.
In this bath the arsenious acid acts as a parasiticide and the sulphate of iron as an astringent, the latter checking the absorption of toxic principles by the skin and sores, and preventing the sheep from licking themselves.
Absorption by the skin is not so dangerous as has been believed. Rossignol has shown that poisoning need not be feared in chemical baths unless the proportion of dissolved arsenic is above 150 grains per quart, especially if the period of immersion does not exceed five minutes. Even pure solutions of arsenic, free from any astringent, may be used, provided the quantity in the bath does not exceed 120 grains per quart.
The bath should, if possible, be kept warm—85° to 95° Fahr. (30° to 35° C.).
Four men are generally employed for the operation. One drives in the sheep, two others hold and brush them in the bath, and the fourth holds the head of the animal above the liquid. Tessier recommended gloves for the use of the operators, but experience has shown that such a precaution is unnecessary. The udder, and particularly the teats, of ewes with young may, if necessary, be smeared with some fatty substance, such as vaseline or oil, in order to guard against the astringent action of the liquid.
Each sheep is plunged in the bath for one or two minutes, or five minutes at the most. All the diseased spots must be brushed, rubbed and cleansed; but care must be taken not to make them bleed.
Tessier suggested leaving the animals for twenty-four hours in some disinfected place, without straw or food, to prevent these materials from being wetted by the liquid which runs from the fleece, and which, if afterwards eaten, might have a poisonous effect. Here, again, the danger has been exaggerated. Delafond has shown that sheep may be given a fluid ounce of Tessier’s bath for eight days running without producing the slightest unfavourable symptom.
Tessier’s bath is excellent from the therapeutic standpoint, but it imparts a yellow tint to the fleece, which is thus rendered less
valuable. The mixture has therefore been modified in various ways.
Clément’s Bath (1846).
For 100 sheep
Arsenious acid 1·5 parts or lbs.
Sulphate of zinc 5 „
Water 100 „
In this bath every quart contains about 2½ drachms of arsenious acid. Its toxic power, therefore, is considerably greater than that of Tessier’s bath.
Clément’s formula has one drawback. The sulphate of zinc may be mistaken for a non-astringent alkaline sulphate (sulphate of soda), and as a consequence poisoning may occur, as experience has shown.
Mathieu of Sèvres replaced the sulphate of iron by an equal quantity of alum. In this case, each quart of the bath contains 2½ drachms of arsenious acid.
Clément’s and Mathieu’s formulæ have given just as good results as Tessier’s.
A last formula is that of Professor Trasbot. The aloes is of very little use, however, because it is almost insoluble.
For 100 sheep
Arsenious acid 2 lbs.
Sulphate of zinc 10 „
Aloes 1 „
Water 25 gallons.
Condition of the animals after the bath.—On leaving the bath the abraded parts are slightly cauterised. During the five or six following days the skin is stiff, and covered with adherent crusts over the points attacked by the parasites. The animals no longer scratch or bite themselves.
Towards the eighth day the crusts fall, the skin appears supple and of a pink colour, and the wounds cicatrise. In animals which have suffered for a long time recovery is much slower, and may extend
over from thirty to fifty days. The wool again grows soft and bright, while the sheep rapidly regain their spirits and condition. The cicatrisation of the wounds is often accompanied by intense itching, which must not be taken as a sign of the persistence of the disease. It is well, however, to keep the animals under observation at this period.
Under any circumstances, six weeks or two months should always be allowed to elapse before giving a second bath. Should a few spots appear to be attacked secondarily, they may be moistened with a little of one of the bath liquids.
In Germany the creolin bath is generally employed:
For 100 sheep { Water 250 gallons or parts.
{ Creolin 6·5 „
Each sheep is bathed a second time after an interval of one week, the animal being immersed for three minutes in the bath and thoroughly scrubbed with a brush. The efficacy of this method, however, is less certain.
In America, where the flocks are large and scabies is frequent, sulphur baths are employed, the baths themselves being of great size. The animals are forced to pass through them and remain there for some minutes.
The size and value of American, Australian, and New Zealand flocks demand that the modes of treatment practised and the experience gained in these countries should receive something more than passing notice. We therefore purpose giving a short résumé of some parts of the very valuable monograph on sheep scab issued in 1897 by Dr. Salmon and Mr. Stiles, for the American Bureau of Animal Industry.
In selecting a dip the question of expense will naturally arise; next, the question as to whether or not scab actually exists in the flock to be dipped. The facilities at hand, the set-back to the sheep, and the length of the wool are also matters for consideration, as well as the pastures into which the dipped sheep are to be placed.
Expense.—In estimating the expense one should consider not only the actual outlay for the ingredients of the ooze, but the cost of fuel
and labour, the injury, if any, to the sheep, and the liability of not curing the disease. It is much more economical to use an expensive dip and cure scab, than it is to use a cheap dip and fail to cure it.
Does scab exist in the flock?—If scab does not actually exist and the wool is long, the dipping in this case simply being a matter of precaution, it is best not to select a dip containing lime.
The facilities at hand for preparing dip.—If fuel is very scarce, so that it is impracticable to boil the mixture for at least two hours, the lime-and-sulphur dips should not be selected.
F . 256. A comparatively early case of common scab, showing a bare spot and tagging of the wool.
The pastures.—In case it is necessary to place the dipped sheep on the same pastures they occupied before being dipped, it is always best to use a dip containing sulphur. If a proprietary dip is selected
under those circumstances, it is suggested that sulphur be added, about 1 lb. of flowers of sulphur to every 6 gallons of dip. The object in using sulphur is to place in the wool a material which will not evaporate quickly, but will remain there for a longer period of time than the scab parasites ordinarily remain alive away from their hosts. By doing this the sheep are protected against reinfection.
Sulphur is one of the oldest known remedies for scab; its use is best known in the tobacco-and-sulphur dip and in the lime-andsulphur dip. These home-made mixtures are the two dips which have played the most important rôles in the eradication of scab from certain English colonies, and their use is extensive in America.
The Tobacco-and-Sulphur Dip.
F . 257. A slightly advanced case of common scab.
The formula as given here, and as adopted by the New South Wales sanitary authorities, appears to have first been proposed in 1854 by Mr. John Rutherford. “On the Hopkins Hill Station Mr. Rutherford, with two dressings of these ingredients, then cured over 52,000 sheep which had been infected for eighteen months. Since then millions of scabby sheep have been permanently cured in Victoria in the same way, and in South Australia and New South Wales hundreds of thousands of scabby sheep have also been cleansed with tobacco and sulphur. Judging, therefore, from the experience of the three colonies, there is no medicament or specific yet known that can be compared with tobacco and sulphur as a thorough and lasting cure for scab in sheep.” (Dr. Bruce, Chief Inspector of Sheep for New South Wales.)
The proportions adopted by Rutherford, and afterwards made official by the scab sanitary authorities, are—
Tobacco leaves 1 lb.
Flowers of sulphur 1 „ Water 5 gallons.
The advantage of this dip lies in the fact that two of the best scab remedies, namely, tobacco (nicotine) and sulphur, are used together, each of which kills the parasites, while the sulphur remains in the wool and protects for some time against reinfection. As no caustic is used to soften the scab, heat must be relied on to penetrate the crusts.
Directions for preparing the dip.—Infusing the tobacco:—Place 1 lb. of gold-leaf or manufactured tobacco for every 6 gallons of dip desired in a covered boiler of cold or lukewarm water, and allow to stand for about twenty-four hours; on the evening before dipping bring the water to near the boiling point (212° Fahr.) for an instant, then remove the fire and allow the infusion to stand overnight.
Thoroughly mix the sulphur (1 lb. to every 6 gallons of dip desired) with the hand in a bucket of water to the consistency of gruel.
When ready to dip, thoroughly strain the tobacco infusion from the leaves by pressure, mix the liquid with the sulphur gruel, add
enough water to make the required amount of dip, and thoroughly stir the entire mixture.
Lime-and-Sulphur Dips.
Under the term “lime-and-sulphur dips” is included a large number, of different formulæ requiring lime and sulphur in different proportions.
To give an idea of the variety of the lime-and-sulphur dips, the following list is quoted, the ingredients being reduced in all cases to avoirdupois pounds and United States gallons:
(1.) The original “Victorian lime-and-sulphur dip,” proposed by Dr. Rowe, adopted as official in Australia:
Flowers of sulphur 20⅚ lbs.
Fresh slaked lime 10⁵₁₂ „ Water 100 gallons.
(2.) South African (Cape Town) official lime-and-sulphur dip, February 4th, 1897:
Flowers of sulphur 20⅚ lbs.
Unslaked lime 16⅔ „ Water 100 gallons.
(3.) Fort Collins lime-and-sulphur dip:
Flowers of sulphur 33 lbs.
Unslaked lime 11 „ Water 100 gallons.
(4.) A mixture which, used to some extent by the Bureau of Animal Industry, contains the same proportions of lime and sulphur (namely, 1 to 3) as the Fort Collins dip, but the quantities are reduced to—
Flowers of sulphur 24 lbs.
Unslaked lime 8 „
Water
100 gallons.
In case of fresh scab Formula No. 4 will act as efficaciously as the dips with a greater amount of lime, but in cases of very hard scab a stronger dip, as the Fort Collins dip, should be preferred; or, in unusually severe cases, an ooze with more lime in proportion to the amount of sulphur, such as the Victorian (No. 1) or the South African (No. 2) dip might be used.
Prejudice against Lime-and-Sulphur Dips.
There is at present great prejudice (a certain amount of it justified, no doubt) against the use of lime and sulphur, emanating chiefly from the agents of patent or proprietary dips and from the wool manufacturers.
In the first place, it is frequently asserted that lime and sulphur does not cure scab. Experience in Australia and South Africa, as well as in America, has shown beyond any doubt that a lime-and-sulphur dip, when properly proportioned, properly prepared, and properly used, is one of the best scab eradicators known.
It is claimed by some that it produces “blood poisoning.” But the cases of death following the use of lime-and-sulphur dips have been infinitesimally few when compared with the number of sheep dipped in these solutions, and when compared with the deaths which have been known to follow the use of certain proprietary dips. The details of such accidents, so far as they have been reported, have not shown that death was due to any property prepared and properly used limeand-sulphur dip. It is highly probable that the cases of so-called “blood poisoning” of shear-cut sheep are generally due to an infection with bacteria in stale dip containing putrefying material.
The greatest objection raised against the use of lime-and-sulphur dip is that it injures the wool. This objection is raised by many wool manufacturers and echoed with ever-increasing emphasis by the manufacturers of prepared dips; while, after years of extensive
experience with properly prepared dip, its injury to the wool is strongly and steadfastly denied by the Agricultural Department of Cape Colony.
It is believed that a certain amount of justice is attached to this objection to lime and sulphur as generally used; unless, therefore, lime and sulphur can be used in a way which will not injure the wool to an appreciable extent, we should advise against its use in certain cases; in certain other cases the good accomplished far outweighs the injury it does. Let us, therefore, examine into this damage and its causes.
258. A more advanced case of common scab.
The usual time for dipping sheep is shortly after shearing, when the wool is very short; whatever the damage at this time, then, it can be only slight, and the small amount of lime left in the wool will surely do but little harm.
In full fleece lime and sulphur will cause more injury. In Australia the deterioration was computed by wool buyers at 17 per cent.,
F .
although in Cape Colony the Department of Agriculture maintains that if properly prepared, and if only the clear liquid is used, the sediment being thrown away, the official lime-and-sulphur formula will not injure the long wool. The United States Bureau of Agriculture have found some samples of wool injured by dipping, while on other samples no appreciable effect was noticeable.
If a lime-and-sulphur dip is used, care must be taken to give the solution ample time to settle; then only the clear liquid should be used, while the sediment should be discarded. In some of the above tests on samples of wool it was found that the dip with sediment had produced very serious effects, even when no appreciable effects were noticed on samples dipped in the corresponding clear liquid.
Experience has amply demonstrated that a properly made and properly used lime-and-sulphur dip is one of the cheapest and most efficient scab eradicators known, but its use should be confined to flocks in which scab is known to exist, and to shorn sheep, with the exception of very severe cases of scab in unshorn sheep. It should only be used when it can be properly boiled and settled. The use of lime-and-sulphur dips in flocks not known to have scab, especially if the sheep are full fleeced, cannot be recommended; in such cases tobacco, or sulphur and tobacco, is safer and equally good.
All things considered, where it is a choice between sacrificing the weight of sheep and to some extent the colour of the wool by using tobacco and sulphur, and sacrificing the staple of the wool by using lime and sulphur, the owner should not hesitate an instant in selecting tobacco in preference to lime. The loss in weight by using tobacco and sulphur is not much greater than the loss in using lime and sulphur, while the loss in staple is of more importance than a slight discoloration.
Preparation of the mixture.—Take 8 to 11 lbs. of unslaked lime, place it in a mortar-box or a kettle or pail of some kind, and add enough water to slake the lime and form a “lime paste” or “lime putty.”[8]
8. Many persons prefer to slake the lime to a powder, which is to be sifted and mixed with sifted sulphur. One pint of water will slake 3 lbs. of lime if the slaking is performed slowly and carefully. As a rule, however, it is necessary to use more water. This method takes more time and requires more work than the one given
above, and does not give any better results. If the boiled solution is allowed to settle the ooze will be equally safe.
Sift into this lime paste three times as many pounds of flowers of sulphur as of lime, and stir the mixture well.
Be sure to weigh both the lime and the sulphur. Do not trust to measuring them in a bucket or to guessing at the weight.
Place the sulphur-lime paste in a kettle or boiler with about twenty-five to thirty gallons of boiling water, and boil the mixture for two hours at least, stirring the liquid and sediment. The boiling should be continued until the sulphur disappears, or almost disappears, from the surface; the solution is then of a chocolate or liver colour. The longer the solution boils the more the sulphur is dissolved and the less caustic the ooze becomes.
Pour the mixture and sediment into a tub or barrel placed near the dipping vat and provided with a bung-hole about 4 inches from the bottom, and allow ample time (two to three hours, or more if necessary) to settle.
When fully settled draw off the clear liquid into the dipping vat, and add enough water to make a hundred gallons. Under no circumstances should the sediment be used for dipping purposes.
F . 259. A shorn sheep with large bare area due to scab.
To summarise the position of the United States Department of Agriculture on the lime-and-sulphur dips:—When properly made and properly used these dips are second to none and equalled by few as scab eradicators. There is always some injury to the wool resulting from the use of these dips, but when properly made and properly used upon shorn sheep, it is believed that this injury is so slight that it need not be considered; on long wool the injury is greater and seems to vary with different wools, being greater on a fine than on a coarse wool. This injury consists chiefly in a change in the microscopic structure of the fibre, caused by the caustic action of the ooze. When improperly made and improperly used the lime and sulphur dips are both injurious and dangerous, and in these cases the cheapness of the ingredients does not justify their use. In case scab exists in a flock and the farmer wishes to eradicate it, he cannot choose a dip which will bring about a more thorough cure than will
lime and sulphur (properly made and properly used), although it will be perfectly possible for the farmer to find several other dips which will, when properly used, be nearly or equally as effectual as any lime-and-sulphur dip. There is no dip to which objections cannot be raised.
Arsenical Dips.
There are both home-made arsenical dips and secret proprietary arsenical dips. It is well to use special precautions with both, because of the danger connected with them. One of the prominent manufacturers of dips, a firm which places on the market both a powder arsenical dip and a liquid non-poisonous dip, recently summarised the evils of arsenical dips in the following remarkable manner:
“The drawbacks to the use of arsenic may be summed up somewhat as follows: (a) Its danger as a deadly poison. (b) Its drying effect on the wool. (c) Its weakening of the fibre of the wool in one particular part near the skin, where it comes in contact with the tender wool roots at the time of dipping. (d) Its not feeding the wool or stimulating the growth, or increasing the weight of the fleece, as good oleaginous dips do. (e) The danger arising from the sheep pasturing, after coming out of the bath, where the wash may possibly have dripped from the fleece, or where showers of rain, after the dipping, have washed the dip out of the fleece upon the pasture. (f) Its occasionally throwing sheep off their feed for a few days after dipping, and so prejudicing the condition of the sheep. (g) Its frequent effect upon the skin of the sheep, causing excoriation, blistering, and hardness, which stiffen and injure the animal, sometimes resulting in death.”
Although this manufacturer has gone further in his attack upon arsenic than the United States Bureau of Agriculture would have been inclined to do, it must be remarked that when a manufacturer of such a dip cannot speak more highly of the chief ingredient of his compound than this one has done in the above quotations, his remarks tend to discredit dips based upon that ingredient. Bruce, the Chief Inspector of Live Stock for New South Wales, speaking of
arsenical dips, says: “Arsenic and arsenic and tobacco (with fresh runs) cured 9,284 and failed with 9,271.”
It may be said, on the other hand, that arsenic really has excellent scab-curing qualities; it enters into the composition of a number of the secret dipping powders, and forms the chief ingredient in one of the oldest secret dips used. This particular dip has been given second place (with some qualifications) among the officially recognised dips in South Africa.
Formulæ for arsenical dips.—Finlay Dun recommends the following:—Take 3 lbs. each of arsenic, soda ash (impure sodium carbonate) or pearl ash (impure potassium carbonate), soft soap, and sulphur. A pint or two of naphtha may be added if desired. The ingredients are best dissolved in 10 to 20 gallons of boiling water, and cold water is added to make up 100 gallons. The head of the sheep must, of course, be kept out of the bath.
A mixture highly endorsed by certain parties consists of the following ingredients:
Commercially pure arsenite of soda 14 lbs.
Ground roll sulphur
Water
34½ „
432 gallons (U.S.)
The arsenite of soda is thoroughly mixed with the sulphur before being added to the water.
Precautions in use of arsenical mixtures.—Any person using an arsenical dip should bear in mind that he is dealing with a deadly poison. The following precautions should be observed:
(1) Yards into which newly-dipped sheep are to be turned should first be cleared of all green food, hay, and even fresh litter; if perfectly empty they are still safer. (2) When the dipping is finished, the yard should be cleaned, washed, and swept, and any unused ooze should at once be poured down a drain which will not contaminate food or premises used by any animals. (3) Dipped sheep should remain in an open, exposed place, as on dry ground. (4) Overcrowding should be avoided, and every facility given for rapid drying, which is greatly facilitated by selecting fine, clear, dry
weather for dipping. (5) On no account should sheep be returned to their grazings until they are dry and all risk of dripping is passed.
The feeling of the United States Bureau of Agriculture towards arsenical dips is shown by the following:
Suggestion as to danger.—The formulæ given above are copied from the writings of men who have had wide experience in dipping, but this Bureau assumes no responsibility for the efficacy of the dips given, or for their correct proportions. Furthermore, as long as efficacious non-poisonous dips are to be had, we see no necessity for running the risks attendant upon the use of poisonous dips.
Carbolic Dips.
This class of dips kills the scab mites very quickly, but unfortunately the wash soon leaves the sheep, which is consequently not protected from reinfection in the pastures. If, therefore, a carbolic dip is selected, it is well to add flowers of sulphur (1 lb. to every 6 gallons) as a protection against reinfection.
The advantages of carbolic dips are that they act more rapidly than the tobacco or sulphur dips, and that the prepared carbolic dips are very easily mixed in the bath. They also seem, according to Gillette, to have a greater effect on the eggs of the parasites than either the sulphur or the tobacco dips. The great disadvantages of this class of dips are—first, in some of the proprietary dips, that the farmer is uncertain regarding the strength of material he is using; second, the sheep receive a greater set-back than they do with either lime and sulphur or tobacco.
F . 260. An advanced case of common scab.
The United States Bureau of Agriculture is inclined to be extremely conservative in regard to them, and to advise their manufacturers to prepare them in a guaranteed strength with more explicit directions for use than are to be found in the present circulars.
One of the prominent proprietary carbolic dips was formerly recognised as one of the three official dips in New South Wales, but it has now been erased from the list. In Cape Town carbolic dips are not much used, and in the official reports little is said concerning them.
The United States Bureau of Animal Industry gives the following advice as regards dipping:
(1.) Select a dip containing sulphur. If a prepared “dip” is used which does not contain sulphur, it is always safer to add about 16½ lbs. of sifted flowers of sulphur to every 100 gallons of water, especially if, after dipping, the sheep have to be returned to the old pastures.
F . 261. An American sheep-dipping plant in operation.
(2.) Shear all the sheep at one time, and immediately after shearing confine them to one-half the farm for two to four weeks. Many persons prefer to dip immediately after shearing.
(3.) At the end of this time dip every sheep (and every goat also, if there are any on the farm).
(4.) Ten days later dip the entire flock a second time.
(5.) After the second dipping, place the flock on the portion of the farm from which they have been excluded during the previous four or five weeks.
(6.) Use the dip at a temperature of 100° to 110° Fahr.
(7.) Keep each sheep in the dip for two minutes by the watch—do not guess at the time—and duck its head at least once.
(8.) Be careful in dipping rams, as they are more likely to be overcome in the dip than are the ewes.
