140 NATURAL THEOLOGY. 



VI. The ejaculations can never too often be 

 repeated — How many things must go right for us 

 to be an hour at ease ! how many more for us to 

 be vigorous and active ! Yet vigour and activity 

 are, in a vast phu'ahty of instances, preserved in 

 human bodies, notwithstanding that they depend 

 upon so great a number of instruments of motion, 

 and notwithstandinsj that the defect or disorder 

 sometimes of a very small instrument, of a single 

 pair, for instance, out of the four hundred and 



fibres is almost universal in the muscles of the limb, and the 

 effect is very important. It needs no reference to mechanics to 

 understand, that if we pull obliquely upon a weight we sacrifice 

 a great deal of power. For what advantage, then, is power re- 

 signed in the muscle ? " If 3'ou wish to draw a thing towards 

 any place with the least force, you must pull directly in the line 

 between the thing and the place ; but if you wish to draw it as 

 quickly as possible, and do not regard the loss of force, you must 

 pull it obliquely, by drawing it in two directions at once. Tie a 

 string to a stone A, and draw it straight towards you at C with 

 one hand ; then make a loop on another string, and running the 

 first through it, draw one string in each hand at B B, not towards 

 you, in the line A C, but sideways, till both strings are stretched 

 in a straight line : you will see how much swifter the stone moves 

 than it did before when pulled straightforward. Now this is 

 proved by mathematical reasoning to be the necessary con- 

 sequence of forces apphed obliquely ; there is a loss of power, but 

 a great increase of velocity. The velocity is the tiring required 

 to be gained."* 



By the liberal employment of muscular power, quickness and 

 variety of motion are obtained, and with the advantages which 

 are so well described in the succeeding part of this chapter. 



* Preliminary treatise on the objects, advantages, and pleasures 

 of science. (Library of Useful Knowledge.) 



