( 2$5 ) 
To prove Sir 1 fa ac Newton's Opinion , we are only 
to meafure about one Tenth of an Inch in a Rod of 
39,129 Inches ; and to know what to allow for the 
lengthening of the fame Rod by the Summer Heat, 
when it is (hut up in a Cafe, and carried towards the 
/Equator. For though the Experiments on Pendulums, 
made by feveral Perfons that traveled Southward, dif- 
fer among themfelves, yet they all agree in this, that 
the Obfervers were oblig’d to Ihorten their Pendulums, 
in order to make them fwing Seconds, as they went to* 
wards the ./Equator. And when we come to compare 
them together, in order to have the exad Proportion of 
Length in different Latitudes; we muft rely on the 
moft exad Experimenter, which we may very well do 
on Morif. Richer : becaufe when he found a Difference, 
lie was fo careful to find out how much it was, that he 
caus’d a fimple Pendulum to fwing, and compar’d it 
with a good Pendulum Clock, which he did feveral 
Times every Week for 10 Months together ^ and when 
he return’d to France , he compar’d it with the Length 
of the Pendulum at Taris • which is of 3 Feet 8 * Lines 
(or 39,129 Englijb Inches) and found it to be lhorter 
by 11 Line. 
O 0 
Vol. XXXIII. 
II. An 
