HEAD IN GENERAL. 



89 



lever. But then there are other reasons of a purely mechanical nature 

 (Fig. 28). 



We represent bv the lines AB and AC respectively the directions 

 of the head and the neck. The former being very movable, admit- 

 ting of extension and flexion, we 

 represent the direction of the exten- 

 sors and flexors by the dotted lines 

 Ce and Cd, in order to show at 

 Avhat angles they are inserted upon 

 their lever-arm, the head. It is to 

 be remarked that when the obliquity 

 of the head is carried to an angle 

 of 45 degrees, the extensors and the 

 flexors have an incidence approach- 

 ing a perpendicular direction, which 

 they will nut have when the head 

 has any other inclination. 



The animal respires more easily 

 (the larynx being neither in a state 

 of compression nor exaggerated ex- 

 tension), responds more promptly to 



the bit, is more readily controlled, and executes with greater facility 

 any movements of the head which may be demanded. 



When the head is carried horizontally, the centre of gravity is 

 elevated and displaced forward and the stability of the equilibrium is 

 lessened. The larynx and trachea are placed in a straight line, facil- 

 itating the entrance and exit of air. The body being tlien in a state 

 of unstable equilibrium, the hind limbs', which are principally concerned 

 in locomotion, can more easily displace the centre of gravity, the foi'e 

 limbs, in order to avoid falling forward, move more rapidly, and loco- 

 motion is thereby increased.^ 



This position is not maintained at rest, but only during exercise, 

 and more especially in horses which are ewe-necked and in young 

 saddle-horses at the beginning of their dressing, when they are not yet 

 habituated to the action of the bit. This attitude is expressed by say- 

 ing that the animal carries his head toicards the scent. 



If there are some advantages in horses carrving: their heads in this 



Fig. 28. 



1 It Is a well-known fact that in our fastest trotting-horses the height of the posterior 

 extremities exceeds that of the withers. This excess is an additional aid to the displacement 

 of the centre of gravity by the hind limbs, according to the principle enunciated, and hence 

 favors an increase of speed. An opposite conformation will diminish speed. (Harger.) 



