192 



EQUINE LOCOMOTION 



Movement must have some point of departure, and we will assume that 

 our subject is in the position which Barrier and Goubaux, Le Coq and 

 Stillman, Hayes and Marey all assume as possible, though Captain Hayes 

 alone, among the authorities named, while admitting the possibility of an 

 attitude such as is assigned to the horse by Goubaux, adds, " I have never 

 seen a horse adopt it". Without insisting upon minutiae we may suppose 

 our horse to be standing as nearly "square" as a horse will. In any change 

 of attitude the centre of gravity will be shifted, and recovered by obtaining 

 a new base of support. 



In the slow pace of walking there is no elevation of the centre of 

 gravity, and consequently no danger of losing the equilibrium; but in the 



faster paces this danger ex- 

 ists, as will be readily seen 

 in the illustration of a horse 

 extended at the gallop, with 

 the head advanced to the 

 utmost limit which other 

 conditions of its carriage 

 will permit (fig. 529). The 

 draught -horse (pushing, be 

 it remembered, for it is not 

 draught 1 ] lowers his head 

 (when not artificially re- 

 strained by the bearing - 

 rein), and so brings forward 

 the centre of gravity. With the advance of a limb a new base of 

 support is obtained, and as long as the centre of gravity falls within 

 the base of support, equilibrium is maintained. In raising a limb the 

 resistance encountered is only that of its own weight, or pressure of the 

 atmosphere, and propulsion of the animal above and in front of the per- 

 pendicular line of the centre of gravity is brought about by straightening 

 the limb against the immovable surface of the ground. 



Diminished resistance, as in deep ground, results in a lesser degree 

 of propulsion, apart from the deterrents to progression which arise from 

 suction and the additional weight of soil attached to the foot. A good 

 example of propulsion by straightening of the limbs against a fixed object 

 is that of the swimmer who touches, turns, and strikes off from the side 

 of the bath; the wall being immovable (with the force at disposal), while 

 the water is readily displaced. 



Fig. 529. Equilibrium in the Gallop 



1 The propulsion of a vehicle is brought about by a series of levers bent upon one another between a fixed 

 and a movable point. These levers act against the ground, where the toe is placed, and the collar. 



