134 THE MECHANICAL FUNCTIONS. 



large muscle, which raises the heel, and forms 

 the thickest part of the calf of the leg. 



It very commonly happens in the animal 

 frame, as it does in other machines, that the 

 presence of the moving agent in the spot where 

 its action is wanted, would be exceedingly in- 

 convenient. The usual plan adopted for trans- 

 ferring the effect of the moving power to a 

 distant point is the employment of a rope, or 

 strap. Such is precisely the office of the ten- 

 dons, which are long straps, attached at one end 

 to the muscle, and at the other to the bone, 

 or other part intended to be moved. (See Fig. 

 43). If the hand, for instance, had been en- 

 cumbered with all the muscles which are neces- 

 sary for the movements of the fingers, it never 

 could have performed its office as a delicate 

 mechanical instrument. These muscles, accord- 

 ingly, are disposed high up on the arm, and 

 their tendons are made to pass along the wrist to 

 the joints of the fingers which are to be moved. 



The employment of tendons is accompanied 

 with this farther advantage, that by their inter- 

 vention the united power of all the fibres of the 

 muscle may be obtained, and concentrated upon 

 any particular point. In this respect, likewise, 

 they resemble a rope, at which a great number 

 of men are pulling at the same moment, and 

 whose combined strength is thus brought into 

 action. Another principal use of tendons is 



