486 Dr. Herschel's Experiments on the solar, and 



l^gtb Experiment. 



Invisible rays. Flint glass. 



o' 5°i 49ir 



5 52 5H • • • *£ '• *£ = 1 > 006 



This glass stops no invisible rays of heat. 





150th Experiment. 













Invisible rays. Crown glass. 











0' 



5°i 49i 











5 



5>f 5o|-... 



1-3- 



:i| 



= ,81 



8 



stops 



182 invisible rays of heat. 



151st Experiment. 



Invisible rays. Coach glass. 



54i 53t 



- 





- 







55f 54f • • • 



7 . 



8 " 



3 



4 ' — 



;>857 





It stops 143 invisible rays of heat. 



152^ Experiment. 



Invisible rays. Calcinable talc. 



?' 5 1 ! 5°f 



5 5H 5J| ■ • • *| : ii = ? 750 



This substance stops 250 invisible rays of heat. 



153c? Experiment. 



Invisible rays. Dark-red glass. 



°' 471 $i 



5 4 8 f 47i • • • 1 : 1 = *> 00 ° 



This glass stops no invisible rays of heat. This accounts 



For the strong sensation of heat felt by the eye, in looking at 



