164 Mr. Galbraith on the Figure of the Earth. 
But the polar axis is to the equatorial diameter as 1 to / 1-+A%, 
aiid 1 : 
or ltol + >N— 7a‘ &c. And by substituting for a° its 
value from equation (3) we have » ae 
Bis Cig 20. a0 78 5 275 
vTER= /i+3q as Slt 7d gf &e 
5 278 1 1 
Hence 1 + Ta te g=1lt+ gS a‘, and conse- 
2 1 
quently 2 — ee g=Hanw— Zr Butra= -\ nearly, 
ve 1 : 
therefore a about sFoo000000? Which may be safely neg- 
lected. And finally, 
ae, ie ioe as 55 
N= se¢=FqU- By)... (#) 
- tt SE ace . apne ee 
As qis aor nearly, =5 7 = 0°0033936: therefore 7 = — 
(1— 0:003396) = 2°491516 g very nearly = p. 
But Phil. Mag. vol. lxiv. page 163, 
ee OL cif eau DALE: MAUS Se Oo Vi 
And taking the radius of the equator and time of rotation as 
formerly stated, we have 
5212458 y 
© = 30919576+18500020352 2 77" * (6) 
From Captain Sabine’s observations combined with the French 
in page 351 of his work, he obtains / = 39:01520 + 0°20245 
sin? A; and adopting this, we can on the principles formerly 
laid down, (that is, rejecting those at St. Thomas and Ascen- 
sion, as on basaltic bases,) deduce the length of the equatorial 
pendulum from observations at 
Maranham .... = 39:01175 
Sierra Leone. . . = 39°01556 
Prinidad 20.45. = 39°01193 
Bahia <he aes y-,:° = 39:01402 
Mean . .. = 39:01332 
On the same principles, from observations of the Spanish 
navigators as given in the Connazssance des Tems for 1816, we 
get, at Acapulco ... . . 39°01126 
Manilla .... .. 39°02067¥%» 
Umatag ...... 39°00157 
Zamboanga ... - 39°01379 
LimaMekge als ass 39701046 
Isle Rabao ... . 39:01370 
Mean... . . 3901191 
Also 
