C 365 ] 
went thither to meafure a degree of the meridian, 
which he was pleafed to fend me to Peterfburg; 
this pendulum, which is no other than a fimple fteei 
rod fixed to a lentille, made at Para 98740 ofcilla- 
tions in 24 hours of mean time, and at Paris 98891 
in the fame time. I made experiments with this 
fame pendulum at Peterfburg, before my departure 
for Lapland, and have repeated them fince my return 
thither. They give the number of ofcillations in 
24 hours of mean time 98941, having been care- 
ful to preferve conftantly the fame temperature, and 
to caule the pendulum to fvving very fmall arcs. 
At Ponoi, I found the number of ofcillations 
98946. Hence it follows, that the fimple pendu- 
lum, which beats feconds at Peterfburg, will be 
441,02 lines (Paris meafure), that is, JLL. lin. longer 
than the pendulum which beats feconds at Paris ; 
and the pendulum at Ponoi will be 441,22 lin. that 
is -iL s _ lin. longer than that of Paris. 
The excefs of the Paris pendulum above that at 
the equator has been determined by the academicians 
1,50 lin.; and admitting Sir Ifaac Newton’s principle, 
and Huyhens’, that the increafe of gravity, in ap- 
proaching the pole, follows the ratio of the fquare of 
the fine of latitude, we fhould find 1,98 lin. for the 
excefs of the Peterfburg pendulum above that at the 
equator, inftead of 1,95, which I find by my ex- 
periments ; the fame calculus would give 2,24 lin. 
for the excefs of the Ponoi pendulum, inftead of 
2,15 lin. which refuits from my experiments. 
Hence it would follow that the increments of gravity 
follow a ratio fomewhat greater than that of the 
fquares of the fines of latitude ; and this refult is 
confirmed 
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