12 ON THE EXTERNAL CONFORMATION. 



means of joints. But, on the other hand, as the 

 fore quarters are chiefly employed in sustaining 

 the equilibrium of the machine, the concussion 

 which must have been produced if they had 

 been united to the body by joints, would have 

 been considerably greater than what is produced 

 by their being attached by muscles only. In 

 describing the action of the shoulder, it will be 

 necessary to consider its position when in a state 

 of immobility. 



The scapula or blade bone is placed ob- 

 liquely from the chest to the withers, and the 

 center of its action is fixed in the middle of it. 

 In its action, it describes as large a portion of a 

 circle as the extension of its muscles will admit. 

 If this portion of a circle, for instance, be ten 

 degrees^ and two different scapula possess the 

 same degree of extension, the one situated ob- 

 liquely {inch plate 2, fig. 1) the other perpendi- 

 cularly [fig. 2) it must necessarily follow, that, 

 acting on their respective centers, the one which 



is 



