Transmission of Musical Sounds. 229 



tions are almost inaudible by themselves, and only become 

 strongly audible when augmented by resonant surfaces. 



The vibrations of the sounding-board of any stringed in- 

 strument may be communicated in the same manner as those 

 of a string, or of a tuning fork, to a distant sounding-board 

 by means of a metallic, glass, or wooden conductor ; but in this 

 case it is necessary to prevent the original sounds from being 

 heard through the air, otherwise the communicated sounds will 

 not be distinguishable from them. This may be effected by 

 placing the originally vibrating, and the reciprocating instru- 

 ments in different rooms, and allowing the conductors to pass 

 through the floor or wall separating the two rooms. 



In the passage of the conducting- rod or wire through these 

 partitions, care must be taken to prevent its touching their 

 sides ; for this purpose, a tin tube, covered at its two ends 

 with leather, or India rubber, may be inserted in the partition, 

 and the conductor be made to pass through holes in these 

 coverings, so as not to touch the side of the tube. 



A square piano-forte is a very convenient instrument to 

 employ in these experiments. If the sound is to be trans- 

 mitted upwards, nothing more is requisite than to open or 

 remove the lid of the instrument, and to allow the conductor 

 to rest upon the sounding-board. A metallic wire is not suffi- 

 ciently rigid to support itself thus without bending ; a rod of 

 some straight-fibred wood, as lancewood or deal, is therefore 

 belter adapted for this form of the experiment ; the lower end 

 of the rod must be reduced in thickness, so as to allow it to 

 pass between two adjacent strings ; and the best place to make 

 the contact will be found to be about a quarter of an inch 

 from the bridge, among the middle notes, and on the side 

 occupied by the unvibrating portions of the strings. The reci- 

 procating instrument in the room above, may be a guitar or 

 any other similar instrument, or a harp; in which latter case, 

 the rod may be brought in contact with the inner surface of the 

 belly of the instrument, through one of the apertures of the 

 swell. These were the forms under which the experiments 

 have been repeated at the Royal Institution. 



