LENGTH OF LIMB. 157 



amount to ? It is evident that the longer the hind leg, the 

 greater — other things being equal — will be the speed of 

 propulsion. Excess of height at the croup will, however, 

 be accompanied by two serious drawbacks, namely, it will 

 entail proportionately increased work, during fast paces, on 

 the fore limb {see p. 6-^ and on the muscles of the back 

 and loins {see p. 64) in raising the forehand at each 

 stride ; and, by surcharging the fore legs {see p. 49), it will 

 naturally tend to render these limbs more liable to the 

 injurious effects of work than they would be, were the 

 weight more equally distributed between the fore and hind 

 extremities. Under the former, we would have increased 

 speed purchased by loss of staying power, which is as 

 dependent on the free action of the fore limbs and loins, as 

 it is on that of the hind limbs. Under the latter, the 

 gain in the rate of progression would be obtained at the 

 risk of impaired soundness. Those speedy animals, the 

 cheetah, the Indian black buck, and the grey-hound, are a 

 little longer in the hind limb than they are in front. As 

 a rule, race-horses of the highest class are about the same 

 height at withers and croup. This difference between the 

 racer and the other gallopers may be accounted for by the 

 fact, that the proportion of weight which the fore limbs of 

 the race-horse have to carry, is still more increased by the 

 presence of a jockey on his back. Among the fleet of 

 foot, I purposely omitted mentioning the hare, which is, for 

 its size, the fastest animal of the lot. Its speed, however, 

 can be maintained, as we might have inferred, only for a 

 short distance on level ground ; though it is particularly 

 hard to catch up a hill, the difficulty of ascending which is 

 directly lessened by the fact of the fore limbs being shorter 



