5CX) PHILOSOPHICAL TRANSACTIONS. [aNNO I7O9. 



An Experiment, showing the Propagation of Sound, passing from the Sonorous 

 Body into the common Air, in one Direction only. By Mr. Fr. Hauksbee, 

 T.R.S, N°32i, p. 369. 



Since, by the former experiment, actual sound could not be transmitted 

 through a space void of air; I was inclined to try whether a sound, propagated 

 in a receiver, having a communication with the open air at one small aperture 

 only, but otherwise entirely surrounded by a vacuum, would be increased, or 

 continued sounding longer, at each stroke given the bell, than it would do, 

 were not its body encompassed by such a medium. I therefore included the 

 bell as in the foregoing experiment; only, to the upper part of its receiver, was 

 screwed a box with collars of leather ; and on the top of the outward receiver, 

 was laid a brass-plate with a wet leather between ; in the middle of which plate, 

 was likewise screwed another brass box with collars, as before. These receivers, 

 when placed on the pump, had their boxes standing directly one over the other. 

 Through both of them in that position, 1 passed a hollow brass tube, which 

 exactly fitted their perforations : thus the inner receiver had a communication 

 with the outward air, and the outer receiver was thereby secured from the in- 

 gress of the circumambient medium. Now when the air contained between the 

 receivers was pretty well exhausted, and the bell struck, the sound was sensibly 

 very vigorous, and very nearly as great as before any air was exhausted ; yet if a 

 finger was applied to the aperture of the hollow brass tube, the sound would be 

 so much diminished, as but just to be distinguished. By this we see, that 

 since the sound in that state cannot be transmitted through the receiver that 

 includes it, by means of the surrounding vacuum, yet the receiver is certainly 

 struck with it; but finding no conveyance that way, reverberates and makes its 

 passage where it finds least resistance. Nor did I observe, that though the 

 sound had but one passage from its receiver, and that but a small one, that it 

 continued any longer after the stroke, than if it had been made in the open air. 



An Experiment on the Propagation of Sound through fVater. By Mr. Fr^ 

 Hauksbee, F.R.S, N° 32 1 , p. 37 1 . 

 As a former experiment showed that sound could not be transmitted through 

 a vacuum, I was induced to try what would be the effect, by surrounding the 

 receiver, that contained the sounding body, with so dense a medium as water. 

 Accordingly, as in the former experiment, the receiver which contained the 

 bell was screwed down to a brass -plate, with a leather between ; this receiver 

 with its bell, was suspended in a large glass vessel, by four threads to the top,, 

 and as many to the bottom, by which it remained in the middle between both. 



SI 3 p. 



