60 
i 
PUTNAM. 
portability. As the weight of the pendulum apparatus itself 
is not more than half that of the entire outfit necessary for 
accurate gravity measurements, a reduction in it alone is 
not a very important gain in ordinary work. Undoubtedly 
there will be special cases, however, where this saving of 
weight will be an important consideration, and for such this 
apparatus will be most valuable. 
Comparisons of Results with Different Pendulums .—A good 
opportunity to compare relative gravity results as obtained 
with pendulums of different length and principle is afforded 
by the past season’s work from the fact that the half and 
quarter second pendulums were swung at four stations in 
common, and also because four of the stations had been 
occupied in 1893 by Commandant Defforges, who used his 
three-quarter second (one-half meter) reversible pendulum. 
Below are given the comparative results, all based on the 
same value at Washington, the stations being arranged in 
the order of magnitude of g. The results with the half 
second pendulums on both knife-edges are included, and 
also two stations of Defforges on the Pacific coast, where 
comparison is made with results obtained in 1891 with a 
different set of half second pendulums. In all cases the 
places of observation were practically identical. 
Station. 
Elevation. 
Results for gravity (not re¬ 
duced to sea level). 
Differences. 
34 second pendu¬ 
lums on knife > 
A I. 
34 second pendu¬ 
lums on knife W 
A II. 
C. 
h 
a 
CD . 
P.® 
'S S 
o 
CD 
GO 
Defforges. O 
> 
I 
Q 
A-D. 
Meters. 
Dynes. 
Dynes. 
Dynes. 
Dynes. 
Dynes. 
Dynes. 
Chicago....... 
182 
980.264 
98C.263 
980.249 
980.276 
+.015 
—.012 
Washington..... 
14 
.098 
.098 
.098 
.098 
.000 
.000 
San Francisco....... 
114 
979.951 
979 947 
+.004 
Salt Lake Citv... .... 
1,322 
.789 
.747 
+.042 
Mt. Hamilton...... 
1,282 
.646 
.614 
+.032 
Denver.... 
1,638 
.595 
979.596 
979.593 
.615 
+.002 
—.020 
Pikes Peak..... 
4,293 
978.940 
978.945 
-—.005 
