CHEMICAL INTENSITY OF TOTAL DAYLIGHT IN ECLIPSE OF 1870. 471 
On grouping together the observations taken at about the same hours on the three 
days, the following mean values are obtained : — 
Table II. 
Hour. 
Altitude. 
No. of 
Chemical intensity. 
experiments. 
Diffused. 
Direct. 
Total. 
h m 
8 24 
11 4 13 
1 
•036 
•01 1 
•047 
8 54 
15 9 39 
1 
•050 
•018 
•068 
9 23 
19 9 35 
2 
•068 
•027 
•095 
9 53 
22 22 15 
2 
•080 
•042 
•122 
10 24 
25 8 21 
2 
•095 
•061 
•156 
10 52 
26 28 12 
i 
•097 
•077 
•174 
11 30 
28 43 46 
4 
•108 
•050 
•158 
11 57 
29 5 40 
2 
•118 
•044 
•162 
12 11 
29 0 12 
2 
•113 
•046 
•159 
12 30 
28 37 4 
i 
•108 
•042 
•150 
12 44 
28 7 31 
2 
•110 
•039 
•149 
1 10 
26 46 42 
2 
•105 
•031 
•136 
1 24 
25 48 54 
2 
•103 
•050 
•153 
1 53 
23 21 20 
3 
•088 
•037 
•125 
2 6 
22 3 46 
1 
•082 
•028 
•no 
2 24 
20 5 30 
3 
•078 
•028 
•106 
2 44 
17 40 44 
4 
•062 
•018 
•080 
3 G 
14 46 51 
1 
•060 
•017 
•077 
3 22 
12 32 0 
3 
•053 
•010 
•063 
3 36 
10 28 46 
1 
•049 
•01 1 
•060 
3 55 
7 34 41 
2 
•042 
•005 
•047 
4 34 
1 
1 30 28 
1 
•009 
•000 
•009 
On again grouping the observations made at hours equidistant from noon, we obtain 
the mean numbers contained in the following Table : — 
Table III. 
Mean altitude. 
No. of 
observations. 
Diffused. 
Direct. 
Total. J 
1 30 28 
1 
0-009 
0-000 
0-009 
9 28 10 
7 
0-044 
0-008 
0-052 
13 9 57 
7 
0-050 
0-014 
0-064 
19 57 49 
12 
0-072 
0-028 
0-100 
24 46 12 
7 
0-095 
0-049 
0-144 
28 24 10 
14 
0-108 
0-047 
0-155 
These results are graphically represented in Plate XXII. figs. 1, 2 & 3. 
The observations on the day of the eclipse (the 22nd) were commenced shortly after 
9 o’clock, and up to the time of first contact were made regularly at intervals of about 
an hour. It will be seen from the remarks contained in the last columns of Table I. 
that the fine weather we had experienced up to the 19 th was gradually drawing to a 
close; the barometer gradually fell from 29*97 inches at noon on the 19th to 29'50 
inches at 4.30 p.m. on the 21st; the wind, too, had veered round, and clouds were slowly 
3 t 2 
