on the terrestrial Rays that occasion Heat. 487 



the sun through a telescope, when red darkening glasses are 

 used. 



154/Z) Experiment. 



Invisible rays. Orange glass. 



5 53 52 ... if : 1 = ,727 



It stops 273 invisible rays of heat 



155th Experiment. 



Invisible rays. Yellow glass. 



5 53 52 • . . i| : 1 = ,800 



It stops 200 invisible rays of heat. 



156th Experiment. 



Invisible rays. Pale-green glass. 



5 5^i 5i| . . . 1 : 1 = ,625 



It stops 375 invisible rays of heat. 



157th Experiment. 



Invisible rays. Dark-green glass. 



5 5^i 52 . . . 1 : f = ,500 



It stops 500 invisible rays of heat. 



i5Sth Experiment. 



Invisible rays. Bluish-green glass. 



°' -53 5%i 



5 54i '524. •• if: £ = ,200 



It stops 800 invisible rays of heat. 



3R2 



