fi' Bttptrtmmts and Itiqu'tnes n/peFllng S/wnd and Light. 



VII. 



Outlines of Experiments and Inquiries refpeEling Sound and Light. By TnOMAi Yo-UKG 



M.D.F.R.S.* 



XT has long been my Intention to lay before the Royal Society a few obfervatlons on the 

 fubje£l of found ; and I have endeavoured to coIle£l as much information, and to make as 

 many experiments, conneiSed with this inquiry, as circumflances enabled me to do ; but, 

 the further I have proceeded, the more widely the profpefl: of what lay before me has been 

 extended ; and, as I find that the inveftigation, in all its magnitude, will occupy the leifure 

 hours of fome years, or perhaps of a life, I am determined, in the mean time, left any un- 

 forefeen circumflances (hould prevent my continuing the purfuit, to fubmit to the Society 

 ibme conclufions which I have already formed from the refults of various experiments* 

 Their fubjefts are, I. The meafurement of the quantity of air dlfcharged through an aper- 

 ture. II. The determination of the direflion and velocity of a ftream of air proceeding 

 from an orifice. III. Ocular evidence of the nature of found. IV. The velocity of found. 

 V. Sonorous cavities. VI, The degree of divergence of found. VII. The decay of found. 

 VIII. The harmonic founds of pipes. IX. The vibrations of different elaftic fluids. X. 

 The analogy between light and found. XI. Thecoalefcenceof mufical founds. XII. The 

 frequency of vibrations conftituting a given note. XIII. The vibrations of chords. XIV. 

 The vibrations of rods and plates. XV. The human voice. XVI. The temperament of 

 mufical intervals. 



I. Of the ^antity of Air difcharged through an Aperture. 



A piece of bladder was tied over the end of the tube of a large glafs funnel, and punc- 

 tured with a hot needle. The funnel was inverted in a veflel of wAter ; and a gage, with 

 a graduated glafs tube, was fo placed as to meafure the preffure occafioned by the different 

 levels of the furfaces of the water. As the air efcaped through the puncture, it was fup- 

 plied by a phial of known dimenfions, at equal intervals of time; and, according to the fre- 

 quency of this fupply, the average height of the gage was fuch as is expreffed in the firft 

 Table. It appears, that the quantity of air difcharged by a given aperture, was nearly in 

 the fubduplicate ratio of the preffure ; and that the ratio of the expenditures by different 

 apertures, with the fame preffure, lay between the ratio of their diameters and that of 

 their areas. The fecond, third, and fourth Tables ftiow the refult of fimilar experiments, 

 made with fome variations in the apparatus. It may be inferred, from comparing the 

 experiments on a tube with thofc on a fimple "perforation, that the expenditure is increafed, 

 as in water, by the application of a ftiort pipe. 



• - • Philof. Tranfaaions, 1800, p. 106. 



TaUe 



