194 Mr, Powell's experimental inquiry into the nature of 
(13.) IP. Set. Incandescent iron. Distance 6 inches. 
Glass screen 2 inches from bulbs. 
1 
Experiment. 
1 
1 
Temp, of screen be. 
fore experiment by 
thermometer in con- 
tact. 
Rise of Thermometers in 
1 miiij (centigrade.) 
Temperature of 
screen after ex- 
periment. 
A. White. 
B. Black. 
1 
16.5 
1. 
1.5 
25-5 
2 
16.5 
.5 
1.25 
23-75 
3 
17 
.5 
1.5 
24.5 
4 
17 
.5 
1. 
22.25 
5 
17 
• 5 
1. 
22.25 
Mean 
.6 
1.25 
Effect of the screen alone, 
heated above 25°. 
1 
.25 
.25 
2 
.25 
.25 
The former result diminished 1 _ ^ 
for this effect. 
1 . 
Incandescent iron. No screen. 
1 
3. 
3.5 
2 
3. 
4. 
3 
2.75 
3.5 
4 
3.3 
3.75 
5 
3.3 
4. 
Mean 
y — 
2.95 3.75 
Difference of the exposed and i 
screened results. 1 
2.6 2.75 
