GRAVITY MEASUREMENTS. 
43 
Table B. 
Values of g Computed from Each Pendulum and Knife-edge. 
Number. 
Station. 
Knife-edge. 
g (in dynes). 
Differences from 
mean. 
Pendulum 
A 4. 
Pendulum 
A 5. 
Pendulum 
A 6. 
Mean of 
three pend¬ 
ulums. 
A 4. 
A 5. 
A 6. 
1 
Boston, Mass. 
I 
980.381 
980.381 
980.384 
980.382 
—.001 
—.001 
+.002 
2 
Cambridge, Mass. 
I 
980.385 
980.382 
980 386 
980.384 
+ 
1 
— 
2 
+ 
2 
3 
Princeton, N. J. 
I 
980.163 
980.166 
980.163 
980.164 
— 
1 
+ 
2 
— 
1 
4 
Philadelphia, Penn. 
1 
980.183 
980.182 
980.182 
980.182 
+ 
1 
, 0 
0 
5 
Washington (Coast and 
Geodetie Survev). 
I, II 
980.098 
6 
Ithaca, N. Y. 
I 
980.284 
980 288 
980.285 
980 286 
_ 
2 
+ 
2 
— 
1 
7 
Charlottesville, Va. 
I 
979.922 
979 925 
979.926 
979.924 
— 
2 
+ 
1 
+ 
2 
8 
Deer Park, Md... 
I 
979.920 
979.923 
979.920 
979 921 
— 
1 
+ 
2 
— 
1 
9 
Cleveland, Ohio . 
I 
980.225 
980.225 
980.230 
980.227 
— 
2 
— 
2 
+ 
3 
10 
Cincinnati, Ohio . 
I 
979.991 
979.987 
979.993 
979.990 
+ 
1 
— 
3 
+ 
3 
11 
Terre Haute, Ind . 
I 
980.056 
980.061 
980.058 
980 058 
— 
2 
+ 
3 
0 
t o 
Gln'/ioirn Til 
I 
980.267 
980.262 
980.264 
980.264 
+ 
3 
— 
2 
0 
JLZ 
omeago, in...•< 
II 
980.263 
980.263 
980.262 
980.263 
0 
0 
— 
1 
13 
St. Louis, Mo . ... 
I 
979.985 
979.985 
979 990 
979.987 
— 
2 
—. 
2 
+ 
3 
14 
Kansas City, Mo . 
II 
979.977 
979.973 
979.979 
979.976 
+ 
1 
— 
3 
+ 
3 
15 
Ellsworth, Kan. 
I 
979.912 
979.911 
979 913 
979.912 
0 
— 
1 
+ 
1 
16 
Wallace, Kan. 
I 
979.743 
979.735 
979 744 
979.741 
+ 
2 
— 
6 
+ 
3 
17 
Colorado Springs, Colo.. 
I 
979.479 
979.472 
979.476 
979.476 
+ 
3 
— 
4 
0 
1 Q 
r 
I 
979.597 
979.595 
979.592 
979 595 
+ 
2 
0 
— 
3 
lo 
Denver, Colo. ■< 
II 
979 597 
979 597 
979.595 
979.596 
+ 
1 
+ 
1 
— 
1 
19 
Pikes Peak, Colo. 
I 
978.940 
978.939 
978.941 
978.940 
0 
1 
+ 
1 
20 
Gunnison, Colo. 
I 
979.327 
979.324 
979.332 
979.328 
— 
1 
— 
4 
+ 
4 
21 
Grand Junction, Colo.... 
I 
979.616 
979 618 
979.623 
979.619 
— 
3 
— 
1 
+ 
4 
22 
Green River, Utah. 
I 
979.626 
979.619 
979.620 
979.622 
+ 
4 
— 
3 
2 
23 
Grand Canyon, Wyo. 
I 
979 890 
979.882 
979.884 
979.885 
+ 
5 
— 
3 
— 
1 
24 
Norris Basin. Wyo.. 
I 
979.935 
979 938 
979.934 
979.936 
— 
1 
+ 
2 
— 
2 
25 
Lower Basing Wyo. 
I 
979 919 
979.918 
979.918 
979.918 
+ 
1 
0 
0 
26 
Pleasant Valley, Utah... 
I 
979 497 
979.500 
979.497 
979.498 
1 
+ 
2 
— 
1 
27 
Salt Lake City, Utah. 
I 
979.788 
979.785 
979.793 
979.789 
— 
1 
4 
+ 
4 
In reducing pendulum observations to the sealevel 
Bouguer’s formula has been very generally used. This is 
H ( 3 d\ 
dg = + 2 g — (1 —^ > where dg is the correction to ob¬ 
served gravity, g is gravity at the sea level, H is elevation 
above sea level, r is radius of the earth, d is density of mat¬ 
ter lying above sea level, and 4 is mean density of the earth. 
The first term takes account of the distance from the earth’s 
center and the second term of the vertical attraction of the 
matter lying between the sea level and station on the sup¬ 
position that the latter is located on an indefinitely extended 
horizontal plain. Whenever the topography about a station 
departs materially from this condition a third term must be 
