II. OUTLINES 

 OF EXPERIMENTS AND INQUIRIES RESPECTING 



SOUND AND LIGHT. 



BY THOMAS YOUNG, M.D F.R.S. 



IN A LETTER TO EDWARD WHITAKER GRAY, M.D. SEC. R.B. 



FROM THE PHILOSOPHICAL TRANSACTIONS. 

 Rtad before the RovAL Society, January 16, 1800. 



DEAR SIK, 



Xt has long been my intention to lay before 

 the Roya! Society a few observations on the 

 subject of sound ; and I have endeavoured to 

 collect as much information, and to make as 

 many experiments, connected with this in- 

 quiry, as circumstances enabled me to do ; 

 but the further I have proceeded, the more 

 widely the prospect of what lay before me 

 has been extended ; and, as 1 find that the 

 investigation, in all its magnitude, will oc- 

 cupy the leisure hours of some years, or per- 

 haps of a hfe, I am determined, in the mean 

 time, lest any unforeseen circumstances 

 should prevent my continuing the pursuit, to 

 submit to the Society some conclusions 

 which I have already formed from the results 

 of various experiments. Their subjects are, 

 I. The measurement of the quantity of air 

 discharged through an aperture. IL The de- 

 termination of the direction and velocity of a 

 stream of air proceeding from an oritice. 



III. Ocular evidence of the nature of sound. 



IV. The velocity of sound. V. Sonorous ca- 

 vities. VI. The degree of divergence of 

 sound. VII. The decay of sound. Vlll. The 

 harmonic sounds of pipes. IX. The vibra- 

 tions of different elastic fluids. X. The ana- 

 logy between light and sound. XI. The 

 coalescence, of musical sounds. XII. The 

 frequency of vibrations constituting .a givea 

 note. XIII. The vibrations of chords. XIV. 

 The vibrations of rods and plates. XV. The 

 human voice. XVI. The temperament of 

 musical intervals^ 



I. Of the Quantity of Air discharged through 

 an Aperture. 



A piece of bladder was tied over the end 

 of the tube of a large glass funnel, and 

 punctured with a hot needle. The funnel 

 was inverted in a vessel of water ; and a gage, 

 with a graduated glass tube, was so placed 

 as to measure the pressure occasioned by the 

 different levels of the surfaces of the water. 



