8o THE HORSE IN MOTION. 



turn or waste of power by correcting deflection of the line in wliich it 

 is intended the body shall move. This rendered necessary the use of 

 the legs alternately, so that while one should be performing these 

 functions the other should be moving in the reverse direction, to take 

 its place and permit as little loss of time as possible between the end 

 of the performance of one limb and the beginning of that of the next. 



If we have comprehended the movements of a limb and the relative 

 value of the forces that produce them, the levers on which they act 

 and the relation of the limbs to each other, we ought to be able to 

 determine the mechanical elements of the qualities desired in a horse. 

 If speed is desired we must look for those mechanical conformations 

 of parts that determine speed, but this speed must be attained at the 

 expense of power. The anterior limbs must conform in their mechan- 

 ical force to the posterior, and vice versa. It was observed of the pos- 

 terior limbs that long full propellers (the vasti and glutei), low hip joint 

 set well back, so as to afford room for long femur and tibia, gave great 

 length of limb when extended, enabling it to support the weight of the 

 body and exert its propulsion for a longer time, at the same time the 

 power was more directly applied when the head of the bone was lower 

 down. So far as these principles can be applied to the anterior limbs 

 they hold true of them as of the posterior extremities. 



It was observed by Bishop that all animals distinguished for great 

 speed have the angles of the bones most inclined to one another. But 

 while this mechanical arrangement gives great advantage for speed it 

 is a source of weakness in bearing burdens and hauling. 



The requirements for the anterior extremities, to be in harmony 

 with the posterior ones, would be a long oblique scapula and long 

 humerus : these bones long, the angle formed by them would neces- 

 sarily be less obtuse. The great pectoral and great dorsal are the 

 muscles that hold the mechanical relation to the anterior extremity 

 that the great gluteus and vastus do to the posterior; and to give equal 

 advantage to them the thorax should be long to give sufficient distance 

 between the ribs of origin and the insertion at the shoulder. 



The application of propulsion to the anterior limb is unlike that to 

 the posterior, and as it is an advantage in the latter to have the heads 



