a completed whole, from the mind of the inventor, as Athena sprang full-armed from the head of Zeus. The fact seems to be that no human mind is capable of inventing a complete and successful machine without many trials, failures, modifications, and detailed and piecemeal improvements. Even such a simple device as a bicycle passed through a long and interesting evolution before it reached a stage which made it genally useful and popular. The automobile is another illustration of gradual and detailed improvement after it was actually in use. If it is impossible for any human intelligence to invent and construct at once a satisfactory automobile, it would be obviously impossible to have invented and organized a whole industrial system. It would present an infinitely more difficult problem than the invention and construction of any machine that was ever built. It has been by age-long trial and error, variation and selection, experiment and failure, that even a tolerably successful industrial system has been worked out. There are doubtless endless improvements yet to be made, but they will certainly be made by the same process of gradual and piecemeal adjustment. Anyone who thinks that he can devise and organize a better system than the present shows, by the very fact that he thinks so, that he is unfitted for the task. He shows that he lacks the first element in fitness; namely, a knowledge of the vastness of the problem and the infinite number of difficulties to be overcome. It is different, however, with one who thinks of some detail in the present industrial system which might be improved. This presents a problem worthy of the greatest minds, and it also furnishes a possibility of genuine achievement.

CHAPTER XI

POWER

Power needed for moving material objects. It has been pointed out in Chapter VIII that man's work, on the physical side at least, consists in moving material objects. For this work the first essential is power. The power first applied was, of course, that which was generated in his own body and exercised through his own muscles. But the secret of the industrial success of modern civilized nations lies in their command of other sources of power rather than in any superior muscularity of their own.

Animal power. The first of these other sources of power which man utilized on a large scale was that of animals which he domesticated and enslaved. They are still one of the most important sources, if not the most important source, of power. According to the Yearbook of the United States Department of Agriculture there were on the farms of the United States on January 1, 1916, about 25,731,000 horses and mules, to say nothing of those in use in the cities and towns. The latest figures for horses and mules not on farms are those given in the census of 1910. On April 15 of that year there were 3,543,000. Assuming that there were as many in 1916, it would bring the total up to 29,184,000. Some of those on farms, of course, are colts too young to work. Those of working age, both on farms and not on farms, are probably close to 25,000,000. Besides horses and mules, a few oxen are still used. The "primary horse power" (that is, horse power in its original sense) used in manufacturing in the United States in 1914 was estimated at 22,547,574. It has been increasing rapidly, so that by 1916 it was certainly much larger. It is not easy to compare the

actual working power of a horse with that of the horse-power unit as used in measuring the power of a steam engine, but, assuming that they are equal, it would appear that the total animal power in use in the United States is very nearly as great as the total steam and water power used in manufacturing.

Among the animals which have furnished power for man's work may be named the horse, the mule, the ass, the ox, the buffalo, the camel, the elephant, the reindeer, the llama, the dog, and the goat. Of these, the most important for the north temperate zone is the horse, though the ox is a close second. Originally, in fact until very modern times, the horse was used mainly to carry man himself or loads of material on his back rather than for traction; that is, for pulling or drawing loads. Such traction as he was required to perform was the drawing of war chariots and carriages of state, and, later, carriages and vehicles for the conveyance of travelers. His speed fitted him especially for this work. For the slower and heavier work of plowing, harrowing, and drawing heavy loads of farm produce the ox was long considered superior. In the first place, he was larger and heavier than the horses of that day. His heavy body and short legs and his general anatomy seemed to fit him peculiarly for pulling. He fights by pushing with his head. This seemed to call into play the same muscles, bones, and joints as are used in pushing on the yoke. During the last century or so the horse and the mule have been gradually displacing the ox even in agriculture.

Displacement of the ox by the horse. Two factors have contributed to this change from the ox to the horse and the mule as a source of power for farm work. One is the development of large and heavy breeds of horses of such strength and docility as to fit them as well as oxen for the pulling of heavy loads. The other is the development of farm machinery. All large breeds of horses, however, have been developed in the northwestern parts of Europe; that is, in Great Britain, northern France, Belgium, Holland, and Denmark. Whether this is due

to something in the soil or climate, or simply to the ability of the people of those countries as animal breeders, it is impossible to say. Russia and Hungary are also horse-breeding countries and use horses to a certain extent for traction purposes, but they have not produced such huge draft horses as the other countries mentioned. The United States is also breeding large numbers of heavy draft horses, but we have imported our breeding stock from Great Britain, France, and Belgium. We surpass all other countries, however, in the number, quality, and speed of our trotting horses. The lighter breeds of horses. not only lack the weight necessary for drawing heavy loads but they are also likely to be too nervous and excitable. The United States and Canada, together with the countries which originated the heavy breeds, have pretty generally substituted the horse and the mule for the ox even in farm work.

The mule. Southern Europe and the southern part of the United States have made large use of the mule. This hybrid, combining something of the patience and endurance of the ass with the size and strength of the horse, is admirably adapted to farm work in climates where the huge draft horses of the north suffer from the heat, and where the lighter horses of the south are too nervous and excitable for the slow, heavy work on the farm. Even the ass has played a humble though useful rôle by furnishing power to those who could not afford a more expensive animal, such as a horse or a mule.

Both the horse and the mule, even the huge draft breeds, have one great advantage over the ox; that is, their more rapid gait. While they cannot trot as well as the lighter breeds of horses, they can trot very much better than the ox and they can walk much faster, and in farm work it is this faster walk which counts.

The factor which has had a great deal to do with the substitution of the horse and the mule for the ox is the increased use of agricultural machinery. This has required power of a superior kind, and the horse has proved to be much better

adapted than the ox to the drawing and handling of machinery. This is mainly because of his more rapid gait. When the farmer has his money invested in expensive machinery, it is important that he get as much work out of it as possible. He can scarcely afford to allow it to run so slowly as would be necessary if it were drawn by oxen.

Farm machinery. Still another factor which has contributed to this end is the higher wages for farm labor in the countries of northwestern Europe, Canada, and the United States. If a farmer were hiring labor at a very low wage, it would not be so important that he get the most possible work out of his hired man. But when labor is expensive, it works very much as it does when tools and machinery are expensive. It is thus important that as much as possible shall be accomplished by each laborer. It is therefore better to give him a fast-walking team than a slow-walking team.

Historical importance of the ox. The ox, however, from the most ancient times until quite recently, has been the chief if not the sole draft animal of all the races that have used draft animals at all. His docility and patience, his great strength, the cheapness of his harness, and his ability to find his own living when not at work, contributed to make him a most valuable assistant to man in his struggle for the conquest of the earth. In the pulling of the heavy wooden plows and harrows that were in use before the modern steel tools were invented, and the lumbering carts that were in use before modern vehicles were constructed, he enabled men to cultivate the soil on a vastly more extensive scale than would have been possible by human muscles alone. He thus contributed to the production of food for increasing populations of men, and in the end he contributed his own body to help feed them, and his own hide in order that they might be shod. In many parts of the world he is still the principal draft animal for farm work. In southern Europe, southern Asia, and parts of South America one may still see magnificent teams of oxen