LET. VII. AND DISCOVERIES. Ill

its surface. The intensity, or power of gravity,is also to be determined from the weight of thebody under consideration; those which are theheaviest, or weigh the most, being always ob-served to descend with the greatest force; andthose that weigh the least, with the least force:so that the weight of every body may always beconsidered as the just measure of its gravity, orthe force by which it is made to fall towardsthe earth.

It may be asked, if the same body, beingconveyed to different places upon the earth’ssurface, will always have the same weight ?Those who have superficially considered the sub-ject, will certainly imagine this to be the cafe ;but by numberless experiments, the truth ofwsiich cannot be doubted, it is easy to provethe contrary. The weight of a body under theEquator is less than at either of the Poles; andin every other situation, it varies in a certainproportion to the latitude of the place. Thisdifference, however, is not to be discovered bymeans of a balance, or the scales which areusually employed upon these occasions; becausethe weight, against which the body is opposed,is subject to the same variation. The methodby which it has been determined, is by observa-tions made on the vibrations of pendulums ofequal lengths, which are found to move swifterat London or Paris, than under the Equator.

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