490 
PROFESSOR A. SCHUSTER ON THE DIURNAL 
The amplitudes of the variation are given in Table XVIII. where the second 
column gives the calculated values on the hypothesis which we must reject, while 
the third column gives the same numbers calculated on the assumption of an 
external cause. 
The calculated numbers are much larger than the observed ones, which is a fact 
requiring explanation. But, the range of vertical force differing from year to year, 
we must confine ourselves in our reasoning pi’incipally to the Lisbon observations. 
The changes in the range of different years, as far as we have any observations, 
are not so considerable, however, as to account for the discrepancies at Bombay or 
Greenwich, and we must conclude, I believe, that also for those stations a considerably 
smaller range is obtained in the observed than in the calculated forces. 
Table XVI.-—Observed and calculated values of the coefficients h and of vertical 
force, when expressed in the form cos [t — q) + cos 2 {t — on the sup¬ 
position that the disturbing force is inside the Earth. 
Bombay. 
Lisbon. 
Greenwich. 
St. Petersbui'g, 1870 . 
„ 1878. . 
ti. 1 ^2- 
1 
Calculated. 
Observed. 
Difference. 
Calculated. 
Observed. 
DifiFerence. 
h. m. 
23 02 
22 35 
22 06 
21 16 
h. m. 
11 13 
10 40 
8 42 
3 10 
7 05 
h. m. 
+ 11 49 
+ 11 58 
- 11 57 
- 5 54 
- 9 49 
li. m. 
9 55 
11 42 
11 32 
10-48 
h. m. 
4 23 
5 60 
5 56 
7 05 
6 12 
li. m. 
+ 5 32 
+ 5 52 
+ 5 36 
-|- 3 43 
+ 4 36 
Table XVII.—Observed and calculated values of the coefficients h and 0 when 
expressed in the form tq cos [t — q) -f-cos 2 [t — O) the supposition that the 
disturbing force is outside the Earth. 
h- 
u. 
Calculated. 
Observed. 
Difference. 
Calculated. 
Observed. 
Difference. 
h. m. 
li. m. 
h. m. 
h. m. 
li. m. 
h. m. 
Bombay. 
11 10 
11 13 
- 0 03 
3 47 
4 23 
— 0 36 
Lisbon. 
10 37 
10 40 
- 0 03 
5 46 
5 50 
- 0 04 
Greenwich. 
10 03 
8 42 
+ 1 21 
5 38 
5 66 
- 0 18 
St. Petersburg, 1870 . . 
8 52 
3 10 
+ 5 42 
4 38 
7 05 
- 2 27 
„ 1878. . 
7 05 
- 1 47 
• • 
6 12 
- 1 34 
