ON DRAUGHT. 413 



one les, is overcome by the united exertion of two. We shall point out, 

 hereafter, the necessity of attending to this in the application of his power 

 to draught. 



In trotting, the action is of course quicker, and a less resistance will, as 

 might be expected, cause the horse to move his legs at two intervals in- 

 stead of at four equal intervals of time: indeed, a horse accustomed to go 

 in harness generally acquires the habit of that action. There is this strik- 

 ing difference between trotting and walking: in walking, we have seen 

 that the interval between the movement of the legs on the same side was 

 less than the other interval of time : in trotting, on the contrary, the legs 

 situated diagonally, or at opposite corners, move almost simultaneously. 

 Owing to the velocity and the momentum which the body acquires in con- 

 sequence of that velocity, in trotting fast, the successive impulses are less 

 distinctly perceptible, and the movement more continued and uniform than 

 in a slow trot, or in walking. 



In gallopmg, the movement is totally different : the fore legs are thrown 

 forward nearly simultaneously, and the hind legs brought up quickly, and 

 nearly together ; it is, in fact, a succession of leaps, by far the greatest 

 interval of time elapsing while the 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 gal- 

 lop, although it is well known to be the moment when the animal is making 

 no exertion. 



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

 though probably a more artificial pace. The exertion is much less, the 

 spring less distant, and the feet come to the ground In more regular suc- 

 cession : it is a pace of ease, and evidently quite inconsistent with any 

 exertion of draught. 



The consequence of these peculiar movements in the limbs of the animal 

 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 consid- 

 erable impetus or momentum, it must be apparent that the resistance 

 should be such as lo receive each of these impulses, and leave the horse unre- 

 strained in the intervah. 



It must, therefore, be a rigid resistance, void of 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 

 afford frequent opportunities of relaxing the efforts. Neither must it be a 

 yielding resistance, as in that case the animal could not make any great 

 exertion ; for if he applied too much power, he would be liable to fall for- 

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

 would be drawn back by the strain, and it would require a considerable 

 effort to restore the motion. 



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

 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 histantly 

 considerably increasing his velocity, which would be a waste of power ; 

 •lor must he for an instant relax his efforts, or fall below that mark, for he 

 would then be unable even to resist the pull, and would be overcome by 

 the weight. Such an extreme case as this, of course, is not likely to occur 

 often in practice, but the disadvantage of the princiole is obvious. 



