MUSICAL SOUNDS PRODUCED BY HIDROOEN 6AS. $\ 



fo fpeedy as to produce fonorous undulation, I think it will 

 not be impertinent to mention a few fafts relating to that 

 fubjedt. In. the fmall glafs inftrument called the water- /hewn by the 

 hammer, which is a tube of about three quarters of an inch in watcr - hammer » 

 diameter, with a ball of about an inch and half at one end, the 

 other end being hermetically clofed ; the ball contains water, 

 and the empty fpace is rendered nearly vacuous by boiling 

 the fluid previous to fealing it. In this inftrument the heat of 

 the hand, applied to the wetted tube, is fufficient to produce 

 bubbles of vapour which enter the ball, but fpeedily collapfe. 

 The feries of thefe condenfations is as quick as fifteen or fix- 

 teen in a fecond. But in the fleam engine the condenfation is and by the fleam 

 prodigioufly more rapid. I have a fmall double fleam engine en S mc « 

 on the conflru6tion of Boulton and Watt, having all the parts 

 and gear of the large engines, but its cylinder is only 2y inches 

 diameter, and the length of firoke 6 j inches. When this was A fmall fleam 

 fet to work the other day, in a lecture to my pupils, it gave en ? me working 

 600* ftrokes per minute. By an eafy calculation it will be t h e balanceof a* 

 fhewn, that the fleam condenfed was then much more than 300 watch J and con- 

 cubic inches per fecond; and if the condenfation, initead of f Veam'in aS 

 being effected in matTes of about a pint at a time, could havecond. 

 been performed by fucceflivc collaptions of each cubic inch in 

 an open fpace, the pulfes would have produced the tone of This condenfa- 

 the lowefl E flat in the treble cliff. But the number of cubic tion » lf }Y fue " 

 inches condenfed in a large fleam engine, for example, a three wouldVJve "' 

 feet cylinder with an eight feet flroke, will be eight or nine very loudE flat, 

 times as much, at the ufual rate of working. 



* About twice as many as the beats of a common watch , 



V. Account 



