RESULTS OF A TRANSCONTINENTAL SERIES OF 
GRAVITY MEASUREMENTS. 
BY 
George Rockwell Putnam. 
[Read before the Society, February 2, 1895, and published by permission 
of the Superintendent of the U. S. Coast and Geodetic Survey.] 
The value of pendulum measurements of gravity in con¬ 
nection with problems important alike to geodesy and terres¬ 
trial physics can be fully developed only by their systematic 
distribution over the earth’s surface. A prominent member 
of this Society wrote a few years since “pendulum observa¬ 
tions are far too few for the wants of geographic or geologic 
science.” The great expense and labor connected with these 
determinations, using the older instruments and methods, 
acted as such a prohibition to their extension that the entire 
subject was practically neglected for half a century, but 
within recent years interest has revived to so great a degree 
that the total number of stations determined is now prob¬ 
ably five times the number available (122) when Professor 
Helmert, in 1880, made his elaborate discussion of pendulum 
observations to deduce the figure of the earth. This has 
been largely brought about by the introduction of more 
portable apparatus. A quarter meter pendulum and an 
elegant method of using a chronometer in observing coinci¬ 
dences were first employed by Lieutenant Colonel Yon Ster- 
neck, in Austria, about thirteen years ago, and the use of a 
half meter pendulum was developed by Commandant Def- 
5—Bull. Phil. Soc., Wash., Voh 13. 
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