On the Heat in the Sun’s Rays. 381 
effect. But the most striking results were obtained by concen- 
trating the rays with a lens. One was placed in the receiver 
with its focus directed upon an additional thermometer, th 
second and third columns in the following table contain the tem- 
peratures of the air and in the sun, and the fourth, the heat in 
e focus, while the air in the receiver was heated as before. 
The atmosphere at the time was not entirely clear. 
No. of obs,|Temp. of air./ Temp. in sun.|Heat in focus,} 
1 rE 3 104 
if 3 114 
30 D( 
84. D 
90 10: 
00 L¢ 
04 14 
2 OU he Co te 
1 
4 
ry 
S 
, 
3 
) 
} 
4 38 
) ‘ 
L 
104 
The burning glass was then so arranged that being within the 
receiver its focus was on the outside. The result was as follows: 
No. of obs./Temp. of air.|Temp. in sun.|Heat in focus. | 
1 44 50 60 
2 51 60 60 
3 58 68 62 
4 62 72 62 
5 "3 83 a, 
6 96 106 pe 
centrated light. LS E 
The subject is unfinished, and it is my intention to resume 1 
2 some future occasion. 
