70 Mr Buchanan, On a solar Calorimeter used in Egypt 
The diagram Fig. 9 shows the progress of the eclipse and the 
portions of the sun successively uncovered. 
From Table IY. we see that when distillation has begun, it in- 
creases at a much greater rate than does the exposed sun’s surface. 
This must be so in the early stages, because we see that it is not 
till 26 minutes after totality and when already 33 per cent, of the 
sun’s surface has been uncovered that the water in the boiler boils, 
and it takes 16 minutes more before any distillate is collected. 
Even when 50 per cent, of the sun is exposed the rate of distilla- 
tion is only 0'4 c.c. per minute. After this more weight may be 
attached to the observations, but their numerical significance is 
not great. The experiment was not originally contemplated. The 
instrument was constructed for use with the strongest uneclipsed 
sun that could be found. Still it shows that useful information 
could be obtained by arranging for making trustworthy observa- 
tions during the progress of an eclipse. The provisions which it 
would be necessary to make are instructive, because they indicate 
some of the capabilities and defects of the instrument. 
Table IV. 
Apparent 
Solar 
Time, 
A.M. 
Cubic 
centims. 
col- 
lected 
Mean date 
and 
Interval, 
A.M. 
Minutes 
from 
Totality 
Rate of 
Distillation 
Amount 
of Sun’s 
surface 
exposed 
hr. 
min. 
sec. 
hr. 
min. 
sec. 
c.c. per min. 
8 
34 
0 
0 
0 
o-ooo 
9 
1 
0 
0 
27 
0-329 
9 
17 
0 
0 
9 
19 
30 
1 
9 
18 
15 
44 
0-400 
0-509 
9 
21 
0 
0 
9 
29 
30 
5 
9 
25 
15 
51 
0-589 
0-609 
9 
36 
5 
10 
9 
32 
47 
58-5 
0-759 
0-703 
9 
40 
55 
15 
9 
45 
45 
20 
9 
40 
55 
67 
1-034 
0-788 
9 
47 
0 
0 
9 
51 
15 
5 
9 
56 
0 
10 
9 
51 
30 
77-5 
1-111 
0-864 
9 
59 
50 
15 
10 
4 
5 
20 
10 
0 
0 
86 
1-237 
0-924 
10 
5 
0 
0 
10 
8 
52 
5 
10 
14 
35 
11 
10 
9 
45 
96 
1-146 
0-987 
10 
18 
40 
16 
10 
22 
20 
20 
10 
18 
30 
102-5 
1-161 
1-000 
