328 



NATURAL THEOLOGY. 



example, are transmitted through a chain of 

 bones, some of which are not greater in diameter 

 than a horsehair. We are reminded that the 

 undulations visible to the eye or felt by the finger 

 are not the motions of sound, although they ac- 

 company them, and that they must be of a nature 

 much more minute and delicate. There is no in- 

 stance of one organ of sense conveying the know- 

 ledge of a quality of matter for the perception of 

 which another organ is provided. Still, perhaps, 

 these microscopic observations may assist our in- 

 vention. When a powerful lens is applied to a 

 metaUic cord sounding, and we distinguish the 

 brilliant particles on its surface, those particles 

 have not the motions merely to and fro which are 

 caused by the division and subdivision of the 

 elastic cord : those brilliant particles dance in 

 figures infinitely varied, combined of circles and 

 angles which it is perhaps impossible to describe 

 and reduce to any system. Such facts aid us in 

 comprehending how diflferent motions of sound 

 may be commimicated at the same moment. 



It is ascertained that if a metallic rod be placed 

 in contact with a sounding-board to which the 

 sounds of many instruments playing in concert 

 are communicated, and if that rod be extended to 

 a great length, or if it be carried through a par- 

 tition, so that we are out of ear-shot of the instru- 

 ments, and if the rod communicate at its further 

 end with another sounding-board, the motions of 



