No. 8.| PENDULUM OBSERVATIONS. 61 
sider that the irregular movements which could be imparted to the ship, through 
her drifting with the ice, would cause an increase in the observed value for 
the acceleration at each separate place, we may conclude from the above re- 
sults, that the force of gravity over the polar basin cannot be greater than 
the normal. On account of the close agreement between the observed and 
the calculated values, it seems to me reasonable to assume that the force of 
gravity over the polar basin is normal. The circumstance that on January 
16th, 1894, the acceleration was found too small, will be more fully dis- 
cussed later on. 
At the two stations on the 14th and 23rd November, separate pendulums 
were fortunately employed: and as the stations are only about 26 km. distant 
from one another, and very nearly in the same latitude, we may consider a 
combination of these two observations to be equal to a complete observation 
with both pendulums at the same station. As the latitude is not far off 86°, 
the period of the oscillation may be reduced so as to apply to that latitude. 
The reduction-formula that may be employed is 
48=18 (9) — pea 
where y, and @ are the latitude at the two places, and 6 the constant in 
the formula 
g=k(i-+ bsin*9). 
As the gravity may be considered normal, we may take for b the 
value in Helmert’s formula, and put 6 = 0:00531. 
By this means we find that the correction to a latitude of 86° 
for the period of pendulum 33, Nov. 14,=— 3X 10m < 
» oo” = «4 — 34, Nov. 23, =—7X10~‘; 
and the period in a latitude of 86° thus becomes, 
for pendulum 33, S,,—= 05056014 
ees Liga | Mean, 0°5057268. 
7" — 84, S,, = 05058524 f 
If the observations of the 29th and 30th April, 1896, are reduced in a 
similar way to one latitude, namely 84°, the reduction 
for April 29th, = + 12 x 10 —" 
30th, = + 10 x 107‘ 
” n 
