ON DRAITGIIT. 537 



interval of time elapsing while tlie legs are extended after the leap is 

 taken : this is the position, therefore, which catches the eye, and which 

 must be represented in a drawing to produce the effect of a horse in a 

 gallop, although it is the moment when the animal is making no exertion. 

 The canter is to the gallop very much what the Avalk is to the trot, 

 th6uo-h probably a more artificial pace. The exertion is much less, the 

 sprin^'o- less distant, and the feet come to the ground in more regular suc- 

 cessio°n : it is a pace of ease, quite inconsistent with any exertion of 



The consequence of these pecuHar movements in the Hmbs of the ani- 

 mal is that a succession of impulses is conveyed to the body ; and when 

 the movement is slow, and the body of the horse does not acquire any 

 considerable impetus or momentum, the resistance should be such as to 

 receive each of these impulses, and leave the horse unrestrained in the 



intervals. . •-, x. i .• -^ 



It must, therefore, be a rigid resistance, void ot elasticity. 

 It must not, however, be a constant unremitted resistance. 

 For it is a well-known fact, that, however powerful may be the muscles 

 of a limb, they must not be kept constantly on the stretch. Thus we feel 

 even more fatigue by standing than by walking, because one particular set 

 of muscles is then kept constantly exerted. It is evident, therefore, that 

 the resistance or draught must not be perfectly constant, but should aflord 

 frequent oiu^ortunities of relaxing the efforts. Neither must it be a yield- 

 ing resistance, as in that case the animal could not make any great exer- 

 tion • for if he applied too much power, he would be hable to fall forward; 

 and should he at any time fall short of the necessary exertion he would 

 be drawn back by the strain, and it would requii^e a considerable eflort to 



restore the motion. -n i i v 



If a horse be made to drag a rope passing over a pulley and descenchng 

 into a well with a certain weight, say of 200 lbs., attached to it, it is 

 obvious that he could not make an effort greater than 200 lbs. without 

 instantly considerably increasing his velocity, which would be a waste ot 

 power; nor must he for an instant relax his efforts, or fall below that 

 mark for he would then be unable even to resist the puU and would be 

 overcome by the weight. Such an extreme case as this of coui-se, is not 

 Hkely to occur often in practice, but the disadvantage of the prmciple is 



° ITarrangement of this sort is, indeed, sometimes made use of for 

 raising the earth from excavations, or the materials of a buildmg ; but the 

 exertion is continued only for a few seconds, or for a distance of not more 

 than ten or twenty yards : if prolonged, the inconvemence would be 

 seriously felt, as it is, to a certain degree, intoAvmg canal boats ; the length 

 and curve of the rope give an elasticity to the stram, and the necessity of 

 keeping the rope out of the water, or fi-om dragging along the toAving- 

 path compels the animal to keep up a constant unremitted pull, and that, 

 too in an oblique direction, so as to throw him into an unfavoui-able posi- 

 tion We accordingly find that, in these cii-cumstances, the average work 

 of a horse is equivalent only to about four-fifths of that given by Smeaton, 

 Desao-uiUiers, and others, who estimated the power of the horse from the 

 work°dono in a horse-mill, where the resistance is inelastic and aU cir- 

 cumstances favourable, >vith the exception of the circiilar path. 



The disadvantage of this kind of resistance is well known to carmen 

 though of coui'se without consideration of the reason. A horse is said 

 to pull better whenhe is close to his work, that is to say, when he is attached 

 at once to the body to be moved, because every exertion he makes is then 

 communicated at once to the mass ; but the leader of a team, unless he 



