168 ' KESONANCE. [SECT. xvn. 



qualities of tone. This has been beautifully illustrated by 

 Professor Wheatstone in a series of experiments on the trans- 

 mission through solid conductors of musical performances, 

 from the harp, piano, violin, clarinet, &c. He found that all 

 the varieties of pitch, quality, and intensity are perfectly 

 transmitted with their relative gradations, and may be com- 

 municated through conducting wires or rods of very consider- 

 able length, to a properly disposed sounding-board in a 

 distant apartment. The sounds of an entire orchestra may be 

 transmitted and reciprocated by connecting one end of a me- 

 tallic rod with a sounding-board near the 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 pleasing ; the sounds, indeed, have 

 so little intensity as scarcely to be heard at a distance from 

 the reciprocating instrument : 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 miniature 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 intensity of some one 

 note in unison with the air in the cavity is often augmented 

 to a great degree. Any vessel will resound if a body vibrat- 

 ing the natural note of the cavity be placed opposite to its 

 orifice, and be large enough to cover it ; or at least to set a 

 large portion of the adjacent air in motion. For the sound will 

 be alternately reflected by the bottom of the cavity and the 

 undulating body at itsmouth. The first impulse of the undulat- 

 ing substance will be reflected by the bottom of the cavity, 

 and then by the undulating body, in time to combine with the 



