VOL. XC.] 



PHILOSOPHICAL TRANSACTIONS. 



76l 



Min. Candle. 



Exper. 82. 



60 

 63f 



Min. Candle. 



Exper. 83. 



Exper. 84. 



Exper. 85. 



Exper. 86. 



Exper. 87. 







5 

 Min. 







5 

 Min. 







5 



Min. 

 

 5 



Min. 

 

 5 



59| 

 63| 



Candle. 



59| 



63 



Candle. 



591 

 63 



Candle. 

 55$ 

 59 



Candle. 

 551 



59i 



Crown glass 5 one side rubbed on 

 emery ; the rough side exposed. 



60 This glass, so prepared, stops 741 scat- 

 601 . . . 3f : I = .259. tered rays of flame-heat. 



Coach glass j one side rubbed on 

 emery 3 the rough side exposed. 



m 



604 . . . 3| : 1 J = .333. It stops 667 scattered rays of flame-heat. 

 Crown glasss ; both sides rubbed on emery. 



59f It stops 6 i 5 scattered rays 



61 ... 3J : 1| = .385. of flame-heat. 

 Coach glass ; both sides rubbed on emery. 



Min. Candle. 



Exper. 88. 

 5 

 Min. 

 Exper. 89. 

 5 

 Min. 

 Exper. 90. 

 5 

 Min. 

 Exper. 91. 

 5 

 Min. 

 -Erper. 92. 



Exper. 93. 



Min. 

 

 5 



56| 



594 

 Candle. 



60 



63 

 Candle. 



604 



Candle. 



574 

 61 



Candle. 



57i 



6oh 

 Candle. 



57| 



604r 



59% 



6(>§ . . . 3-t : 1 = .320. 



/Crown glass. \ One side of each rubbed 

 \ Coach glass. / on emery. 



551 



56| . . . 3-L : 1 = .280. 

 / Crown glass. \ Both sides of each rubbed 

 \ Coach glass./ on emery. 



55-| 

 57 . . . 34 : 4 = .333. 



{Crown glass ; the rough side to the candle. 

 Coach glass ; ditto. 

 Crown glass ; rough on both sides. 

 Coach glass ; ditto. 



S6\ 



57i... 24: 4 = .130. 



Olive-colour, burnt in glass. 

 60 * 



It stops 680 scattered rays 

 of flame-heat. 



These glasses stop 720 scattered 

 rays of flame-heat. 



These glasses stop 667 rays of 

 flame-heat. 



These four glasses stop 87"0 scat- 

 tered rays of flame-heat. 



604. ..3 

 White paper. 



571 



57±...3 

 Linen. 



571 



This glass stops 79% scattered rays of 



4 = .208. flame-heat. 



This substance stops 792 scattered rays of 



5 = .208. flame-heat. 



58£ ... 34 : 14 = .310. It stops 690 scattered rays of flame-heat. 



White persian. 



57 



584. ..34 

 Black muslin. 



57| 



59 ... 24 : 



14 = .407. It stops 593 scattered rays of flame-heat. 



= .435. It stops 565 scattered rays of flame-heat. 

 Transmission of the Solar Heat which is of an Equal Refrangibility with Red 

 Prismatic Rays. — The apparatus which I have used for transmitting prismatic rays, 

 is of the same construction as that which has already been described under the 

 head of direct solar transmissions ; but here the holes in the top of the box are 

 only 2 inches from each other, and no more than 4-ths in diameter, fig. \*J, pi. 

 13. On the face of the box are drawn two parallel lines, also 4-ths of an inch 

 distant from each other, and inclosing the transmitting holes : they serve as a di- 

 rection by which to keep any required colour to fall equally on both holes. The 

 distance at which the box is to be placed from the prism, must be such as will 

 allow the rays to diverge sufficiently for the required colour to fill the transmitting 

 holes ; and the balls of the thermometers placed under them ought to be less than 

 these holes, that the projected rays may pass around them, and show their proper 

 adjustment. The diameters of mine, used for this purpose, are 2\ tenths of an inch. 



VOL. XVIII. 5 E 



