( i8 7 ) 
therefore the Length of Pendulums at 'Paris , will be to 
their Length at the ^Equator, as 95 to 9 5, $6z, &c. that 
is, as 440,555, &c. to 443 165, &c. and confequently 
they muft be lengthen’d z,6i &c. Lines. Bat as from 
Monf. Mairari s Principles, the Diminution of Gravity 
by the Centrifugal Force, is greater at the ./Equator than 
at ‘Parts , hardly ^ Part of the whole Gravity at the 
^Equator, the Pendulums muft be (hortened in that Pro- 
portion; fothat then the Length of a Second-Pendulum, 
will be 440,555 -f- i,6 1 — 1 Lines. Bat as that Quan- 
tity is greater than 440,555, &c. therefore the Pendu- 
lums upon the Whole muft be lengthen’d : Nay, though 
we fhou’d allow a (hortening of two Lines 3 ftnee by Ob- 
fervation Pendulums are found to be about two Lines 
Shorter at the Equator, the oblong fpheroidical Figure 
of the Earth cannot be confident with the Experiments 
on Pendulums. 
1 beg Leave to fet down Monf. Mairan's aforefaid 
Demonftration here ; that we may fee whether he has 
aftum’d true Principles. 
PROPOSITION V. 
“ * XL The Centrifugal Force at any ^Degree of 
“ Latitude , taken upon the oblong Spheroid, between 
“ the /Equator and the Pole, is left in Comparifon 
“to the Centrifugal Force at the / Equator , than it 
“ won' d beat the fame^Degree of Latitude taken upon 
lC a Sphere • or, which is the fame thing, the Centri - 
“ Jugal Force encreafes more, going from the Poles 
* towards the /Equator, upon an oblong Spheroid , 
“ than upon a perfett Sphere ; and confequently Gra - 
“ vity diminijhes more^ and a Pendulum muft be more 
See Men/. MairanV Dijfertation , Article XI. &c. 
Sf 2 
Jhortened 
