248 THE EXTERIOR OF THE HORSE. 



with that of the canon. In this connection, all authors are agreed that 

 a short canon at the extremity of a long leg constitutes a great point. 

 But why ? No one has explained it. Still, it is easy to account for it. 

 The reasons are of the same nature as those which have been explained 

 in connection with the forearm. 



Here, also, the metatarsus, at the time of contact, plays the part of 

 a lever, at the superior extremity of which the weight of the body is de- 

 composed into two secondary forces : the one, perpendicular to the canon, 

 tending to carry the hock backward ; the other, parallel to this segment, 

 showing the intensity with which the foot presses against the ground. 

 The latter force, destroyed by the resistance of the soil, is for us void 

 of interest. As to the former, it has the metatarsus for its lever-arm, 

 while the extensors of this region are its antagonists. The shorter this 

 arm will be, the less will be the muscular force required to counteract 

 the tendency to flexion. Not only this, but, during the impulsion, 

 the extension of the canon will equally be effected without any greater 

 expenditure of force. 



A canon which is short -relatively to a long leg describes a less exten- 

 sive arc of a circle, and is less heavy. These are additional reasons 

 why the tibial muscles will have to contract with less intensity and to 

 a smaller degree in order to produce the same effect. 



On the other hand, the metatarsus is covered only by tendons, in 

 other words, by inert cords, simple agents of transmission. The tibia, 

 on the contrary, is surrounded by the fleshy portion of the muscles, 

 contractile organs, whose shortening gives the measure of the osseous 

 displacements. Large dimensions should, therefore, be looked for in 

 this region, which, it may be said, constitutes the active part of the 

 segmented pendulum represented by the tibia and the metatarsus. The 

 length of the canon not compensating the shortness of the leg, since 

 its role in locomotion is absolutely passive, there is the best reason to 

 select one that is short in relation with the leg when the object is to 

 combine the best conditions for speed. This consideration in the 

 draught-horse is of no importance. 



Width. The width of the leg is recognized at its superior 

 extremity from before backward, and at the level of the enlarged portion 

 of the extensors. It is always somewhat inferior to that of the fore- 

 arm. 



It indicates the development of the muscles in this zone, and we 

 know that the volume, density, and compactness of the muscles are, 

 in the superior sections of the members, qualities of the first order. 

 A horse with a leg thus muscled is called strong-limbed ; the calf of 



