264 
PROFESSOR FORBES ON THE EXTINCTION OF THE SOLAR RAYS 
Brientz. 
First Series. 
Second Series. 
Hour. 
Log v. 
X. 
Hour. 
Log. v. 
X. 
9 
1-4065 
1529 
84 
1-3579 
1952 
11 
1-4579 
1113 
10 
T4409 
1244 
1 
1-5024 
1111 
12 
1-4857 
1073 
3 
1-3838 
1529 
2 
1-4409 
1242 
4* 
1-2095 
2874 
4 
1-2989 
2184 
Sum. . . 
. . 6-9601 
8156 
Sum. . 
. . . . 7-0243 
7695 
Mean, . 
. . 1-3920 
1631 
Mean . 
. . . 1-4049 
1539 
Taking V = l. 
0] = -7827, 
m — 
•0001402 
Vin 
actinometric degrees = 41 0, 75. 
Faulhorn. 
First Series. 
Second Series. 
Hour. 
Log v. 
X . 
Hour. 
Log v. 
X. 
8 i 
1-3892 
1501 
71 
1-2601 
219 7 
10 
1-5250 
957 
9 
1-4639 
1176 
12 
1-5717 
827 
11 
1-5866 
857 
2 
1-5224 
958 
1 
1-5353 
857 
4 
1-3802 
1683 
3 
1-4698 
1178 
aL 
^2 
1-3304 
2214 
Sum. . . 
. . 7-3885 
5926 
Sum. . 
. . . 8-6461 
8479 
Mean. . 
■ • 1-4777 
1185 
Mean . 
. . . 1-4410 
1413 
Taking V = 1, 
[t>] = "7544, 
m = 
•0001609 
V in 
actinometric degrees = 46 o- 60. 
104 Again, if we compare the whole observations at the Faulhorn in one series 
the whole observations at Brientz in 
another, we 
find 
Mean value of log v. 
Mean value of x. 
Brientz 
1-3984 
1585 
Faulhorn 
1-4577 
1310 
from which we obtain, 
taking V = 1, [t>] = -6857, 
agreeing (as might be expected) almost exactly with the result of Art. 69. p. 252, 
where the same quantity was deduced from the separate simultaneous observations. 
Also we have 
rn = -0002156 
V in actinometric degrees = 54°-97- 
