40 
PUTNAM. 
Approximate aver¬ 
age temperature 
Corrected periods on knife-edge AI. 
| Number. 
Date. 
Pendulum 
A 4. 
Pendulum 
A 5. 
Pendulum 
A 6. 
Mean of 3 
pendulums. 
1 
April 25-27,1894. 
16° C. 
s. 
.5008406 
s. 
.5006662 
s. 
.5006300 
.5007123 
2 
May 10-12,1894. 
19 
8404 
6666 
6304 
7124 
3 
May 31-June 2, 1894.. 
17 
8408 
6664 
6302 
7124 
4 
June 23-25, 1894. 
23 
8408 
6662 
6302 
7124 
5 
Oct. 31-Nov. 2, 1894... 
Jan. 11-13, 1895. 
17 
8400 
6656 
6306 
7121 
6 
11 
8404 
6677 
6294 
7125 
The agreement of the means shows a satisfactory perma¬ 
nency of period, and as the determinations were made at 
different seasons of the year and at various temperatures the 
results may also be taken as throwing some light on the in¬ 
variability of gravity and on the reliability of the tempera¬ 
ture coefficient, although it is possible that some of these 
elements compensate each other. 
The value of g for each station was derived separately for 
each pendulum by comparing its period there with the aver¬ 
age of its periods at Washington before and after the expe- 
P 2 
dition, computing by the simple formula g 0 — j~-g . For 
o 
g w the provisional value heretofore adopted, 980.098 dynes 
(or centimeters in terms of acceleration), at the Coast and 
Geodetic Survey Office was used. This was adhered to for 
convenience, although an elaborate determination of the 
absolute force of gravity made at Washington, in October, 
1893, by Commandant Defforges of the “ Service Geograph- 
ique” of France gave a somewhat larger value, 980.165.* 
Large discrepancies appear among the results of the best 
determinations of absolute gravity made at the base stations 
* ‘‘ Comptes Rendus de l’Academie des Sciences,” 29 January, 1894. For 
description of the apparatus and elegant methods developed and used by 
Commandant Defforges, see 11 Memorial du Depot General de la Guerre, 
tome xv, Observations du Pendule,” Paris, 1894. 
