232 Mr. Wheatstone on the 



room below in a hook ; a third part was suspended from this 

 hook by a loop ; and the fourth, after identifying itself with 

 one of the apparent wires of the lyre, passed within the in- 

 strument, and was ultimately fixed, at its lower end, to the 

 point marked at the end of the dotted line on the sounding- 

 board ; each of the disunited parts were allowed to overlap 

 each other at a and b, and were fastened together by means 

 of a clamp with a screw-nut. The whole apparatus thus pre* 

 pared may be easily removed ; the clamps being unscrewed 

 and the resounding instrument removed, the lower wire must 

 be unhooked from the ceiling, the hook unscrewed, and the 

 middle wire withdrawn from the insulating-tube : the time for 

 fixing or removing the apparatus need not exceed a few 

 minutes. 



From what has preceded, it will be obvious in what manner 

 two square piano-fortes or two harps may be so connected as 

 mutually to reciprocate each other's sounds ; by such an 

 arrangement,, two performers in different rooms may play a 

 duet together to two distinct audiences, or one may echo the 

 performance of the other. If the transmission is required to 

 be horizontal, i.e., between two rooms on the same floor, 

 cabinet piano-fortes must be employed. 



The sounds of an instrument may be at the same time trans- 

 mitted to more than one place ; for instance, communications 

 may be made from a square piano-forte to a resounding in- 

 strument above, and to another below; and the communi- 

 cation may be even continued through a series of reciprocating 

 instruments. If the instruments be not in adjacent rooms, 

 but be further removed from each other, a person in the inter- 

 mediate room, through which the conductor passes, will hear 

 no sound but what is communicated by the ordinary means. 

 Hence it would be possible to extend a horizontal conductor 

 through a series of rooms belonging to different houses, and 

 (provided the instrument connected with one of its extre- 

 mities be constantly played upon) to hear at pleasure the 

 performance in any of these rooms, by merely attaching a 

 reciprocating instrument to the conductor; on removing this 

 instrument, the sonorous undulations would pass inaudibly 



