150 NATURAL THEOLOGY. 



very heavy draught is no more than sufficient to 

 countervail the force ot^ a small lead plummet, 

 placed upon the long arm of the steelyard, at the 

 distance of perhaps fifteen or twenty inches from the 

 centre and on the other side of it. And this is the 

 disadvantage which is meant ; and an absolute dis- 

 advantage, no doubt, it would be, if the object 

 w^ere to spare the force of muscular contraction. 

 But observe how conducive is this constitution to 

 animal conveniency. jMechanism has always in 

 view one or other of these two purposes — either 

 to move a great weight slowly, and through a 

 small space, or to move a light weight rapidly, 

 through a considerable sweep. For the former of 

 these purposes, a different species of lever, and a 

 different collocation of the muscles, might be bet- 

 ter than the present ; but for the second, the pre- 

 sent structure is the true one. Now so it happens, 

 that the second, and not the first, is that which 

 the occasions of animal life principally call for. 

 In what concerns the human body, it is of much 

 more consequence to any man to be able to carry 

 his hand to his head with due expedition, than it 

 would be to have the power of raising from the 

 ground a heavier load (of two or three more hun- 

 dred weight, we^wijl suppose,) than he can lift at 

 present. 



This last is a faculty, which, on some extraordi- 

 nary occasions, he may desire to possess; but the 

 other is what he wants and uses every hour or 

 minute. In like manner, a husbandman or a gar- 



