Table r. 



Emperiments an^ Inqutrles refpeBlng Sound and Light, 



n 



Table II. 



Table IV. 



A IS the area, in fquare inches, of an aperture nearly 

 circular. B, the preflure in inches. C, the number of 

 cubic inches difcharged in one minute. 



All numbers throughout this paper, where the con- 

 trary is not expreffed, are to be underftood of inchesi 

 linear, fquare, or cubic. 



A is the area of the fediion of a tube about two Inches 

 long. B, the prefTure. C, the quantity of air difcharged 

 in a minute, by eftimation. 



A is the area of the feftion of a tube. B, its length. 

 C, the preflure. D, the difcharge in a minute. 



A Is the area of an oval aperture, formed by flattening 

 a glafs tube at the end : its diameters were .025 and .15^ 

 B, the preflure. C, the difcharge. 



II. OftheDireBton and Velocity of a Stream of Air. 



An apparatus was contrived for meafuring, by means of a water-gage communicating 

 with a refervoir of air, the preflure by which a current was forced from the refervoir 

 through a cylindrical tube ; and the gage was fo Crnfible, that, a regular blaft being fup- 

 plied from the lungs, it fhewed the flight variation produced by every pulfatlon of the heart. 

 The current of air ifl\iing from the tube was direfted downwards, upon a white plate, on 

 which a fcale of equal parts was engraved, and which was thinly covered with a coloured 

 liquid ; the breadth of the furface of the plate laid bare, was obferved at different diftances 

 from the tube, and with different degrees of prefl'ure, care being taken that the liquid 

 fiiould be fo fhallow as to yield to the flighteft impreflion of air. The refults are colleded 



Vol. v.— May i8oi. L in 



