ON THE EFFECTIVE TEMPERATURE OF THE SUN. 
391 
Date : September 8tli, 1893. 
Weather: Generally so cloudy that very few observations were possible. 
Barometer, 29‘5 in. 
Position. 
Local 
time. 
Balance. 
Sun’s- 
altitude. 
Per cent, 
trans. 
Angle of 
incidence. 
Per cent, 
reflected. 
Sun’s abs. 
temp. 
Reading. 
Temp. abs. 
h. 
m. 
o 
o 
o 
O 
2B 
11 
44 
60-0 
1378 
41-8 
63-9 
65-0 
12-0 
5982 
11 
45 
60-0 
1378 
41-8 
63-9 
65-0 
12'0 
6982 
11 
46 
60-5 
1386 
41-8 
63-9 
65-0 
12-0 
6016 
Mean . 
5993 
Note. —After the above observations had been made, the aperture through which the radiations from 
the platinum passed into the radio-micrometer was enlarged, as in some cases the balancing tem¬ 
perature became inconveniently high. The dimensions of the new aperture were:— 
Diameter = 5'57 millims. Angle subtended = 6°‘.301. 
