MUSCULAR POWER. 139 



The infinite mechanical skill, with which the 

 moving power has been applied to the purposes 

 to be accomplished, is displayed not only in the 

 larger organs, where great force is to be exerted, 

 but also, in a still more conspicuous manner, in 

 the execution of the smaller motions, requiring 

 the most accurate regulation, and the nicest 

 adjustments. We cannot but be struck with the 

 accordance which may often, in these instances, 

 be traced with human contrivances, when the 

 greater motions are rapidly executed by one set 

 of agents, acting with considerable power and 

 velocity, while the minuter approximations to 

 the exact positions are effected by a distinct part 

 of the apparatus, capable of more delicate action, 

 though with a smaller force. Thus, while the 

 astronomer brings his telescope round by power- 

 ful machinery, so as to direct it to that part of 

 the heavens, where the object he wishes to view 

 is situated, a more nice mechanism is employed 

 to direct the instrument accurately to the exact 

 point ; and again another is provided for making 

 the proper focal adjustments. Many parallel 

 cases occur in the mechanism of the animal 

 frame ; one set of powerful muscles being em- 

 effect and procuring the advantages of a combination of oblique 

 muscles already explained. Thus beautifully is the arrangement 

 of the muscular fibres of the heart calculated to produce the 

 rapid and complete expulsion of its contained blood, with the 

 smallest amount of contraction in the individual fibre:*. 



