SECT. XVII. RESONANCE. 145 



strike the strings so as to make them vibrate at right 

 angles to it. In the guitar, on the contrary, they are 

 struck obliquely, which renders the tone feeble, unless 

 when the sides, which also act as a sounding-board, are 

 deep. It is evident that the sounding-board and the 

 whole instrument are agitated at once by all the super- 

 posed vibrations excited by the simultaneous or consecu- 

 tive notes that are sounded, each having its perfect effect 

 independently of the rest.. A sounding-board not only 

 reciprocates the different degrees of pitch, but all the 

 nameless qualities of tone. This has been beautifully 

 illustrated by Professor Wheatstone in a series of exper- 

 iments on the transmission through solid conductors of 

 musical performances, from the harp, piano, violin, clar- 

 inet, &c. He found that all the varieties of pitch, qual- 

 ity, and intensity, are perfectly transmitted with their 

 relative gradations, and may be communicated through 

 conducting wires or rods of very considerable length, to 

 a properly disposed sounding-board in a distant apart- 

 ment. The sounds of an entire orchestra may be trans- 

 mitted and reciprocated by connecting one end of a 

 metallic rod with a sounding-board near tbe orchestra, 

 so placed as to resound to all the instruments, and the 

 other end with the sounding-board of a harp, piano, or 

 guitar, in a remote apartment. Professor Wheatstone 

 observes, "The effect of this experiment is very pleas- 

 ing; the sounds, indeed, have so little intensity as scarcely 

 to be heard at a distance from the reciprocating instru- 

 ment ; but on placing the ear close to it, a diminutive 

 band is heard, in which all the instruments preserve 

 their distinctive qualities, and the pianos and fortes, the 

 crescendos and diminuendos, their relative contrasts. 

 Compared with an ordinary band heard at a distance 

 through the air, the effect is as a landscape seen in min- 

 iature beauty through a concave lens, compared with 

 the same scene viewed by ordinary vision through a 

 murky atmosphere." 



Every one is aware of the reinforcement of sound by 

 the resonance of cavities. When singing or speaking 

 near the aperture of a wide-mouthed vessel, the inten- 

 sity of some one note in unison with the air in the cav- 

 ity, is often augmented to a great degree. A.ny vessel 

 10 N 



