on the terrestrial Rays that occasion Heat. 505 



215th Experiment. 



White paper. Iron. 



5 54i 55% • • • 3 : 2 i = >75° 



Some time having elapsed between the former observation 



and the present one, this plate of iron was not now so bright 

 as before, and seems to have suffered more than brass or copper 

 from having been laid by : it scatters now only 750 rays of 

 heat, and 10014 of light. 



216th Experiment. 



White paper. Brass. 



o' 50 5*i 



5 53% 55% • • • Si : 4i = 1 >3^ 



It scatters 1320 rays of heat, and no less than 43858 of 

 light, 



Qijtb Experiment. 



White paper. Copper. 



491- 5i|- 



53 55f •••3i : 4 3 = 1 »28o 



It scatters 1280 rays of heat, and 13128 of light. 



QiSth Experiment. 



White paper. Gold-leaf paper. 



54f 55% 



5$k 5^ • • • H : % = ,357 



I changed the tablets to see what difference there might be. 



Gold paper. White paper. 



55% 55% 



5 6 % 57% • •:• f : H .?r >5oo 



