Mr. Galbraith on the Figure of the Earth. 165 
Also we have from several others, as 
Formentera ... . 39°01303: 
Madras’ °F 2°28) ys 39°01275 
San\Blas}i2)4) 4.253 39°01311 
Rio Janeiro ... . 39°01447 
Paramatta .... . 39°01250 
Mean ..... 39°01254 
As these means are tolerably consistent, we may group them 
all thus: 
ie. S9°O1332.* 
2)" 29:01 19 F 
« R 8. 39°01254 
Mean of the whole, or z = 39°01259 inches = 3°25105 feet. 
Substituting this value of z in formula (6), it will become 
a: 52127458 _y 
— “20919576 +.6034152420 = 
or, ¢ = 0008608 — bc. (7) 
Hence from Captain Sabine’s book, page 351, 
20245 ; Byer gt id: 
¢ = 0'008608 — “ag0Ine 0:003419, or org Instead of 
x as he has found it. 
He also gives the ellipticity for the lengths of several equa- 
torial pendulums, page 352, such as 39°0152 and 39°01,-and 
finds the difference inconsiderable. But when he changes the 
equatorial pendulum from 39°0152 to 39:01*, he retains the 
same total increase from gravitation, or 0°20245, with which we 
are by no means satisfied. 
For if the equatorial pendulum be....... 39:01520 
Total increase to the pole .......--- - 0°20245 
The polar pendulum would be . . ....+ + « 39°21765 
Now if the polar pendulum remained the f 
same and the equatorial became .... . i a 
the total increase would be ....--.-+++-- 0°20765 
These substituted in equation (7) would give an ellipticity 
l 
Eee ) 
however, still remains,—are we at liberty to make such changes 
in either? It is at least unsafe. The better way would, in 
our opinion, be to determine the equatorial and polar pendu- 
; 
t- 
_ ® In fact, the ratios of *20245 to 39°0152 and of -20245 to 39:01 are 
nearly ratios of equality, as their value only differs about a unit in the sixth 
place of decimals! How then could there be any difference in the re- 
sulting compression ? 
, differing little from Laplace’s estimate. ‘The question, 
lums 
