THE BEAD AND NECK 



141 



tion of the chest -walls, nearly half the labour, with 

 corresponding expenditure of energy and waste of mus- 

 cular tissue, is saved by the application of elasticity as 

 the principal cause of the contraction which follows 

 each muscular effort by which the act of expansion is 

 performed. 



As already mentioned, the horse's head, owing chiefly 

 to the immense apparatus required to grind its necessary 

 supply of food, is of great weight, and if it had to be 

 supported at the end of the long neck entirely by a mus- 

 cular effort on the part of the animal, great expenditure 

 of force, requiring a still larger supply of food to keep it 

 up, would take place. But, thanks to the structure, 

 attachments and physical properties of the cervical liga- 

 ment, it is no effort whatever to the horse to keep its 

 head in the proper position. In fact, this ligament is so 

 disposed, and of such strength and elasticity, as to allow 

 the head to be moved up or down or from side to side, 

 as required, by a very slight exertion of muscular action, 

 but directly this ceases to return it to the position best 

 suited for a state of repose. 



Probably, if those who have to do with the harness- 

 ing of horses were better acquainted with this admirable 

 mechanical apparatus for holding up the head in a 

 natural and unstrained position, they would think it less 

 necessary to supplement the cervical ligament by an 

 external contrivance for effecting the same object, called 



