yerdet’s constant in absolute units. 31 
At Pixholme. 
Set. 
Log (l +^j =0-0005122. Log (l -g~j =0-0001835. 
Log of observed 
time of vibration. 
Log (1+Jo). 
Log of square of 
true time of 
vibration. 
1 . 
| 0-5673675 
0-0003003 
1-1342895 
2. 
0-5676497 
0-0010159 
1-1341383 
3. 
0-5676615 
0-0009971 
1-1341807 
4. 
0-5674381 
0-0001559 
1-1345751 
5. | 
0-5674734 
0-0002550 
1-1345466 
From these data we get the ratio of the magnetic force at Pixholme to that at Kew, 
for 
H at Pixholme (H at Kew at time of Kew vibrations) . (Vibration time at Kew) 2 /0 ^ 
H at Kew (H at Kew at time of Pixholme vibrations) . (Vibration time at Pixholme) 2 ' 
and the values of H at Pixholme at the times of the optical experiments equal the 
values at Kew at those times multiplied by the above ratio. 
The last columns of the two following Tables supply respectively the numerator and 
denominator of the above fraction. 
Set. 
Dates of vibration experiments 
at Kew. 
Mean value of 
H at Kew 
(Corrected square of 
vibration time at Kew) 
X (Mean value of Ii 
at Kew) 
at these dates. 
3. 
1876. 
April 11,3 p.m 
0-179109 
■ 2-42964* 
2. 
„ „ 3.30 p.m 
0-179132 
2-42759 
3. 
„ ,, 4.0 p.m 
0-179146 
2-42758 
4. 
April 13, 11 a.m 
0-178898 
OO 
K 1 
G) 
5- 
„ „ 11.30 A.M 
0-178856 
2-42618 
6. 
„ „ Noon 
0-178866 
2-42711 
Mean 2-42723 
* Rejected. 
