480 THE MECHANICAL FUNCTIONS. 



dulation of the body from one foot to the other 

 would scarcely ever be performed with perfect 

 equality on both sides, if we trusted wholly to the 

 sensations communicated by the muscles, and if 

 we were not guided by the sense of sight, or some 

 other substitute. Thus a person blindfolded can- 

 not walk far in a straight line ; for, even on a level 

 plane, he will incline unconsciously either to the 

 right or to the left. 



In all quadrupeds, and even also in the quadru- 

 mana, the fore extremities more or less contribute 

 to the support and progression of the body : it is 

 only in man that they are wholly exempted from 

 these offices, and are at liberty to be applied to 

 other purposes, and employed as instruments of 

 prehension and of touch. In the power of exe- 

 cuting an infinite variety of movements and of 

 actions, requiring either strength, delicacy, or pre- 

 cision, the human arm and hand, considered in 

 their mechanism alone, are structures of unrivalled 

 excellence ; and, when viewed in relation to the 

 intellectual energies to which they are subservient, 

 plainly reveal to us the divine source from which 

 have emanated this exquisite workmanship, and 

 these admirable adjustments, so fitted to excite in 

 our breasts the deepest veneration, and to fill us 

 with never ceasing wonder. 



To specify all the details of express contrivance 

 in the mechanical conformation of the hand would 

 alone fill a separate treatise : but I must refrain 

 from pursuing this interesting subject, as, fortu- 

 nately, the task has devolved upon one far more 

 able than myself to do it justice. 



