MECHANISM OF THE HAND. 



Fig. 11. 



bones of the fingers gradually decrease in length ; that they are 

 articulated with a succession of hinge joints ; that they are moved 

 independently, one of another, by a series of 

 muscles acted upon by nerves which are under 

 the complete dominion of the will, the ad- 

 mirable perfection of the organ of prehension 

 and touch may be in some degree appreciated. 



12. "When the movements of the arm, 

 hand, and fingers, are considered collectively, 

 it may be stated, without exaggeration, that 

 in directing the fingers to any object of touch, 

 a hundred muscles are brought into opera- 

 tion, whose contractile power is excited by 

 thousands of nervous filaments, each of which 

 is under the absolute dominion of the will, 

 each action of volition requiring a corre- 

 sponding intellectual exertion. How wondrous 

 this machinery intellectual, physiological, and 

 mechanical, must be, the least reflection upon 

 the manual exercises which are daily per- 

 formed, especially in civilised and polished 

 life, will render manifest. When a performer, 

 for example, executes upon the piano-forte one 

 of the complicated compositions of the modern 

 composers for that instrument, as many as ten 

 thousand notes must be produced by the 

 application of the fingers to the keys. The 

 longest of these pieces is executed in about 

 15 minutes, or, in round numbers, 1000 

 seconds, so that the notes must be produced 

 at the rate of 10 per second, and as each note 

 requires a separate dictate of the will, and 

 each dictate of the will a separate act of the 

 mind, we arrive at the surprising conclusion 

 that these mental acts are performed in this 

 particular case at the rate of 10 per second. 

 Nor can it be said that habit enables the 

 fingers to move mechanically while the mind 

 is passive, and that the facility given by repeti- 

 tion supersedes mental action ; for artists are found so expert as to 

 execute such pieces at sight, never having previously studied them. 



13. The lower members are as eminently fitted for the purposes 

 of support and locomotion as are the superior for prehension. 

 Attached to the hip bones or pelvis, at the external corners, they 

 are so articulated as to have a certain play forward, backward, 



59 



