MUSCULAR MOTION. 117 



corresponding half inch of space through which the leg revolves at 

 the knee, the hoof at the extremity of the lever will move through 

 a space equal in extent to as many feet, and the velocity of mo- 

 tion being augmented in increasing proportion, it is evident that 

 the force with which the foot strikes the ground must be greater 

 even than if the muscles had been prolonged and attached to the 

 foot itself. The increased weight of the horse-shoe at the very 

 extremity of this lever will, when once set in motion, by adding to 

 the momentum, like the weight upon the fly-wheel, augment still 

 more this force ; though, of course, it will require greater exertion 

 in the muscles, and so tend to tire the animal all the sooner. 

 Short cannons, in reference to muscular action, are, therefore, pre- 

 ferable to long ones, because their leverage is less, and because 

 with long arms there is greater length and strength of muscle ; 

 though it will be seen, from what has been said, that, in a mecha- 

 nical point of view, they are not calculated to move with the same 

 degree of velocity as long ones*. 



The muscles of the back, loins, and haunches, are remarkable for 

 their size and power, and for the important parts they perform 

 in progression. It has been before observed, that, for strength, the 

 loins should be " broad and rounded, the haunches fleshy, and the 

 thighs let down to the hockst ;" all which amounts to nothing more 

 than saying, that the muscles constituting these parts should be 

 large and powerful, it being quite impossible that a horse of slender 

 muscularity in these — the most important of all — parts, in propor- 

 tion, can either " go," or " maintain the pace" as a hunter or racer ; 

 the loins being the parts from which, when the hind feet have been 

 projected forward and placed to serve as fulcra upon the ground, 

 the spring is made which impels the whole machine omvard, and 

 the haunches being the chief agents in the propulsion. In racers, 

 as has been observed on a former occasion, the loins and hind quar- 

 ters are considered as of paramount importance ; in greyhounds, in 

 the deer species, in hares, rabbits, &c, in fine, in all quadrupeds of 

 speed, the same conformation is remarkably characteristic ; plainly 



* See what has been said about long and short arms and cannons in the 

 description of the bones, 

 f In Lecture I. 



