30 



CONFORMATION AND ITS DEFECTS 



cartilage of the sternum or breast-bone, and the other horizontally between 

 the middle and lower third of the body. This conclusion has been con- 

 firmed by the experiments of Messrs. Goubaux and Barrier, and may be 

 accepted as approximately correct. 



A B c 



Fig. 18. — Equilibrium 

 A, stable. B, Unstable, c, Neutral 



EQUILIBRIUM 



" A body is said to be in equilibrium when the several forces acting 

 upon it balance one another." The part upon which it rests is termed 



the base of support. It may be neces- 

 sary to point out that there are three 

 conditions of equilibrium, viz. stable, un- 

 stable, and neutral. Of these the two 

 former are more esjjecially concerned with 

 equine conformation and movement. In 

 stable equilihrium a body, when slightly 

 displaced or pushed aside, will return to 

 its original position. If, on the contrary, 

 it tends to move farther away from its original position or to toj^iDle over, 

 its equilil)rium is unstable. 



The conditions which conduce to render equilibrium stable are: 



1. A broad base of support. 



2. That the centre of gravity should be situated low down. 



3. That the line of gravitation should fall at or near the centre of 

 the base. 



From these considerations it would appear, as Goubaux and Barrier 

 have pointed out, that " a horse having a heavy body mounted upon 

 long slender liml)s, drawn close to the median plane, will be endowed 

 with an equilibrium relatively unstable ". While, conversely, a horse 

 standing on short legs, set well apart so as to supply a large base of 

 support, will possess an equilibrium relatively stable. 



The horse in jJi'Ogression is constantly displacing the centre of gravity 

 in one direction or another, and the disturbance of equilibrium which 

 is thereby effected is as constantly being restored by the formation of 

 a new base of support, which will vary both in form and extent with 

 the various movements incidental to the several paces respectively. 



In a standing position the base of support of the horse may be described 

 as an area enclosed within four lines placed nearly at right angles to each 

 other, and extending from foot to foot, as shown in fig. 19. 



In this attitude eciuilibrium presents its highest degree of stability. 

 It is during the fast paces, when the trunk is impelled forward by the 



