THE MUSCLES. 99 



a difierent collocation of the muscles, might be bettei than 

 the present ; but for the second, the present structure is the 

 true one. Now it so happens that the second, arid not the 

 first, is that which the occasions of animal life principally 

 call foi. 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 hundred weight, we will suppose — than he 

 can lift at present. 



This last is a faculty which, on some extraordinary occa- 

 sions, 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 gardener will do more execution by being 

 able to carry his scythe, his rake, or his flail with a sufficient 

 dispatch through a sufficient space, than if, with greater 

 strength, his motions were proportionably more confined and 

 slow. It is the same with a mechanic in the use of his tools. 

 It is the same also with other animals in the use of their 

 limbs. In general, the vivacity of their motions would be 

 ill exchanged for greater force under a clumsier structure. 



"We have offered our observations upon the structure of 

 muscles in general ; we have also noticed certain species of 

 muscles ; but there are also single muscles which bear 

 marks of mechanical contrivance appropriate as well as 

 particular. Out of many instances of this kind we select 

 the following : 



I. Of muscular actions, even of those which are well 

 understood, some of the most curious are incapable of pop- 

 ular explanation ; at least, without the aid of plates and 

 fvgures. This is in a great measure the case with a very 

 familiar, but at the same time a very complicated motion, 

 that of the loiver jaiu ; and with the muscular structure by 

 which it is produced. One of the muscles concerned may, 

 however, be described in such a manner as to be, I think, 

 snfHciently comprehended for our present purpose. The 



