( 2 77 ) 
I. A Differtation concerning the Figure of the Earth . 
(Part the Second. (By the (Reverend J. T. De- 
faguliers, LL, D. F. % S. 
S INCE my * Paper concerning the Figure of the 
Earth was read before the Royal Society, I met 
with a DiiTertation of Monf. Mairan (in the Memoirs 
of the Royal Academy of Tar is, for the Year 172,0.) 
wherein the learned and ingenious Author has taken a 
great deal of Pains to reconcile the Obfervations made 
on Pendulums, (found to befhorterat the ./Equator than 
at Tar is , when they fwing Seconds) with the oblong 
fpheroidical Figure of the Earth, deduced from Monf. 
Cajjmis Meafures. And tho’ upon a ftrid Examination 
of his Conje&ures, and what he gives for Demonftra- 
tions, I do not find Reafon to alter my Opinion con- 
cerning the oblate or flatted Spheroid, which Sir Ijaac 
Newt on has fhewn to be the Figure of the Earth ; yet 
fince it might be thought by fome, who have read MonC 
Mairan' $ Treatife, and afterwards may read mine, that 
I have not confider’d all the Circumftances that He has 
done, and that I have not been exad enough in the Ma- 
thematical Part of my Differtation, becaufe I have drawn 
fome Conclulions from fuppofmgthe Figure of the Earth 
fpherical, when I (hould have fuppos’d it an oblong 
Spheroid ^ I beg Leave to fhew here, wherein I think 
Monf. Mairan is miftaken, and to give thofe additional 
Proofs of my Affertions, which I promis’d the Society 
when I gave in my laft Paper. 
* Vid. Philof. Tranf. N 9 , 386, 387 . 
Vol. XXXIII. R r 
Firffc 
