APPARATUS FOR CONDUCTING SOUND..' 71 



refted upon the rod, but the other end was fufpended by a 

 ribband, from an object which need not be defcribed. 



After the apparatus had been prepared as above mentioned, Sound was con- 

 I introduced my watch into the end trumpet, and on applying tf^jy^ou'gh 

 my ear to the crofs trumpet, I heard the beats much louder this apparatus* 

 than if the watch had been at the di fiance of a few inches 

 only. The found appeared to come out of the crofs trumpet, 

 although the watch was at the diftance of feventeen feet and 

 a half: and when the watch was laid into the crofs trumpet, 

 it was heard equally well at the end trumpet. 



It may not be improper to mention, that the found was in- 

 creafed by introducing a piece of metal, between the crofs 

 trumpet and the rod upon which it refted ; but the manner of 

 producing the belt, etfeft, I found by trial. 



EXPERIMENT 2. 



I placed another prop under the middle of the rod, and laid Bodies In eomtaft 



feveral books upon it in different places; but the rod con- ^ ^ e r ° d did 

 r * ' not prevent the 



veyed the found juft as well as before. efTeft. 



EXPERIMENT 3. 



My affiftant in thefe experiments being feated at the end Converfatlon 



trumpet, and myfelf at the other, a convention took place jSJSJji 



through this apparatus; but in whifpers too low to be heard the rod both 



through the air at that diflance. The converfation afforded wa y s in a whif - 



PCr. 

 us much entertainment ; for when the ear was placed in a 



certain pofition, the words were heard as if they had been 



fpoken by an invifible being within the trumpet. And what 



rendered the deception ftill more pleafing, the words were 



more diftinft, fofter, and more mufical, than if they had been 



fpoken through the air. 



SPEAKING MACHINES. 



What I have to fay on this fubjeel, muft be fo far antici- Ufeful purpofes 

 pated by thefe experiments, as to render any particular de- t0 w *V ch tnefe 

 fcription of mine unneceffary. It may not, however, be im- be applied, 

 proper to mention my conjectures, refpecling fome ufeful 

 purpofes to which this acouftic inftrument may be applied. 

 If a communication founded on thefe principles, were made 

 between a fhop and the dining room, or warehoufe, it might 

 contribute to the difpatch of bufinefs : and initruments made 

 ' on 



