ON DRAUGHT 411 



the weiffht of the body may be supposed to be accumulated, and B the ful- 

 crum, or point of resistance ; AC the direction of the power to be overcome. 



If the le2:s are inflexible, the body, acting; by its c:ravity, tends ni its 

 descent to describe a circle around the point B. but is opposed by the 

 resistance AC ; and it is proved by the law of the resolution of forces, that 

 if BD be drawn parallel to AC, the lengths of the lines AD, AB, and DB 

 represent respectively the proportions between the weight of the body, the 

 strain upon the point of support, and the effect produced; that is, if AD 

 be taken as the measure of the weight of the body, then AB is the measure 

 of the strain upon the legs, and BD or AE the power pulling in the direc- 

 tion of AC. r 1 u J J iu 



Consequently, the effect increases with the weight ot the body and the 

 distance which it is thrown beyond the feet, and is limited only by the 

 capability of resistance at B, or the muscular strength of the legs. This 

 is evidently the case in practice ; for even if the body were brought 

 nearly horizontal, when its weight would act to the greatest advantage, 

 still, if the legs are incapable of resisting the strain, they would yield, 

 and no effect be produced. In a man, this muscular strength of the 

 limbs is very great, and he can lift or carry immense weights, and 

 ascend easily, even loaded, a ladder ; but he is not well adapted to the 

 purpose of dragging : as his own weight is small proportionably to his 

 strength ; and The centre of gravity is low, and by the construction of 

 his body, cannot be thrown far beyond the fulcrum at his feet; con- 

 sequently, however capable his legs may be of resisting a great strain, 

 AE remains small, and his muscular force is not advantageously brought 

 into action. 



A horse, on the contrary, by the formation of the body, can relieve his 

 weight partly fiom his fore-legs; and, extending his hind legs as in 

 fig. 2, throw the centre of gravity a considerable distance in front of 

 his feet B, AE is here proporiionably much greater than in the former 

 case, and the whole of his force is, therefore, advantageously employed. 

 He is in fact, by his mechanical construction, a beast of draught. 



The same train of reasoning which has here pointed out the species of 

 work peculiarly adapted to the different structure of the man and horse, 

 if continued further, will now serve to show the circumstances under which 

 the power of the latter is best applied, and the greatest effect produced. 



We shall here consider both the quality of the draught and the degree. 



And first, it is to be observed, that although the weight of the animal's 

 body is the immediate cause in the action of pulling, yet, as before stated, 

 it is by the action of the muscles in advancing the legs and raising the 

 body, that this cause is constantly renewed, and the effort continued. 

 The manner, and the order of succession in which a horse thus lifts and 

 advances his legs may, of course, influence the movement of his body, 

 and ought therefore to be examined into : accordingly we find that many 

 writers upon draught have touched upon this part of the subject, 

 but they appear to have contented themselves with inventing in their 

 closet the manner in which they conceived a horse must have moved his 

 legs, rather than to have taken the trouble to go out of doors to see 

 what really did take place, and, consequently, many have arrived at 

 erroneous conclusions. The ancient sculptors, who generally studied 

 nature so faithfully, either neglected this point, or otherwise our modern 

 horses, by constant artificial training, have altered their step : for we find 

 in the celebrated frieze, from the Parthenon at Athens, a portion of which, 

 now in England, is more commonly known under the name of the Elgin 

 marbles, the only horses which are represented trotting, have both their 



