One part of the old system, however, remains--namely, that although little horses, well bred, are the fashion, large horses are still employed in heavy work. It must indeed be so. Horses draw by their weight, and not by the force of their muscles, although these, by carrying forward the centre of gravity, assist the application of that weight. It is the weight of the animal which produces the draught, and the power of the muscles serves to direct it. The hind feet form the fulcrum of the lever by which this weight acts against a load, and the power exerted is in proportion to the length of the lever, if the weight remains the same. Large animals, therefore, draw more than small ones, though they may have less muscular power, and are unable to carry weight so well. Nothing can better show that horses draw by their weight than the frequent occurrence that a horse is unable to draw a cart out of a slough until a sack of corn is thrown on his back, when he has little difficulty in doing it. Thus it is, that what are technically called lobbing-goers take more weight with them than horses of better action. As the application of the weight or force proceeds from the fulcrum formed by the hind feet, good hind legs and well-spread gaskins are essential points in a coach-horse. We even sometimes see that a waggon-horse, when brought to pull, will not touch the ground at all with his fore feet. Another reason why little horses are unfit for heavy work is, that they will seldom walk and draw at the same time; for if they walk, they catch at their collars, and do but little. They never take anything like an even share of draught. By calculations as to the mean strength of animals, it appears that a horse drawing horizontally, and at the rate of two miles and a half in an hour, can work for eight hours in succession against a resistance of 200 pounds. If that pace be quadrupled, he finds an eighth part of the time sufficient. Thus we can pretty nearly measure a horse’s power in harness. Whether we are carrying supposed improvement too far, and sacrificing strength and endurance to speed, is a question not difficult to be resolved.