24 d SLANTING OF THE SHOULDER. 



The obliquity or slanting direction of the shoulder effects other 

 very useful purposes. That the stride in the gallop, or the space 

 passed over in the trot, may be extensive, it is necessary that the 

 lore part of the animal should be considerably elevated. The 

 shoulder, by means of the muscles vi^hich extend from it to the 

 inferior part of the limb, is the grand agent in effecting this. 

 Had the bones of the shoulder been placed more upright than we 

 see them, they could not then have been of the length which 

 they now are, — their connection with the chest could not have 

 been so secure, — and their movements upon each other would 

 have been comparatively restricted. 



The slanting shoulder accomplishes a most useful object. The 

 muscles extending from the shoulder-blade to the lower bone of 

 the shoulder are the powers by which motion is given to the 

 whole of the limb. The extent ^nd energy of that motion 

 depend much on the force exerted or the strength of the muscle ; 

 but there are circumstances in the relative situations of the dif- 

 ferent bones which have far greater influence. 



Let it be supposed that, by means of a lever, some one is 

 endeavoring to raise a certain weight. 



A is a lever, resting or turning on a pivot B ; C is the weiifrht 

 to be raised ; and D is the power, or the situation at which the 

 power is applied. If the strength is applied in the direction per- 

 pendicular to the lever, as represented by the line E, the power 

 which must be exerted can easily be calculated. 



Fig. 34. 



In proportion as the distance of the power from the pivot or 

 centre of motion exceeds that of the weight from the same place, 

 so will be the advantage gained. The power here is twice as 

 far from the center as the weight is, and therefore advantage i& 

 gained in the proportion of two to one : or if the weight is equal 

 to 2001bs., a force of lOOlbs. will balance it. If the direction in 

 which the power is applied is altered, and it is in that of the line 

 F, will lOOlbs. effect the purpose? No ; nothing like it. How, 

 then, is the necessary power to be calculated ? The lin-e of 

 direction must be prolonged, until another line, falling perpen- 

 dicularly from the lever, and commencing at the center of mo- 

 tion, will cut it ; and the length of that line will give the actual 



