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* Vibration in a Second to 3 6,6 1 6, which therefore is 
“ the Length of a Pendulum which performs its Vibra- 
“ tions in a Second- at the ^Equator ; fo that the Diffe- 
<• rence between thefe two Pendulums is ?L-.- Parts of an 
“ Inch, which comes pretty near the Obfervations of 
“ Monf. Richer , who at the Ifland of Cayenne, whofe 
<c Latitude is 5 0 0C)/ found that a Pendulum, which vi- 
“ brates Seconds there, was a tenth Part of an Inch 
“ fhorter than a Pendulum, which vibrates Seconds at 
V Tarts. 
“ Thus we fee that the Principles and Hypothefis,' 
“ and withal their Confequences, upon which "the broad 
c/ ‘ fpheroidical Figure of the Earth is founded, do exactly 
“ agree with Obfervations, and therefore there is no 
“ Doubt to be made, butthat the Earth -is really of fuch 
“ a Figure, and that the Hypothefis upon which this 
“ Figure is grounded (viz. the diurnal Rotation of the 
l< Earth, and by confequence the Centrifugal Force of 
<c all Bodies upon it) muff be admitted for a true one * 
<'* fince the different Vibrations of Pendulums of the 
“ fame Length, in different Latitudes, can depend upon 
tc no other Caufe ; for the Change of Air is not able to 
f ‘ produce any fuch Effed, for if the Air made really 
“•any Alterations in the Vibrations of a Pendulum, it 
“ wou’d produce a quite contrary Effed than what is 
<c obferv’d } for Pendulums near the AZquator wou’d 
tc move falter than they wou’d do in Places of greater 
“ Latitude, the Air in the one Place, being more rari- 
“ tied, is much thinner and finer than it is in the other 
t; and therefore gives lefs Refiftance to Bodies that move- 
“ in it. i ' ‘ • • ; - * 
“ In this Reafoning, we have fuppos’d the Earth to 
“ have been at firfl fluid, as the theorift has done be- 
“ fare us, but if we will put the Cafe, that the Earth 
“ was firfl partly fluid and partly dry, as it is at prefent, 
“ yet.: 
