THE FIRST CONVINCING EXPERIMENTAL DEMONSTRATION OF THE UNIVERSALITY OF GRAVITATION

MASKELYNE, NEVIL.

An Account of Observations made on the Mountain Schehallien for finding its attraction. Read at the Royal Society, July 6, 1775 (+) A Proposal for measuring the Attraction of some Hill in the Kingdom by Astronomical Observations.

London, Lockyer Davis, 1775. 4to. In recent marbled paper wrappers. Extracted from "Philosophical Transactions". Including title-page of volume. Leaves reinforced in margin. Very light brownspotting through out and light offsetting from folding plate as usual. (2), iii-vii, (1), 495-542 pp.

First appearance of Maskelyne's paper constituting the "first convincing experimental demonstration of the universality of gravitation" (DSB), in the sense that it operates not only between the bodies of the solar system but also between the elements of matter of which each body is composed.

"In a famous experiment of 1774 Maskelyne attempted to determine the earth's density from measurements of the deviation of a plumb line produced by the gravitational attraction of Mt. Schiehallion, in Scotland. By observing the slight difference in the zenith distances of certain stars at two observing stations on the north and south faces of the mountain, and making due allowance for the effect of their latitude difference by means of geodetic measurements, Maskelyne identified the residual displacement of 11.7" with the sum of the deviations in the direction of the vertical to the earth's surface on each side of this conveniently symmetrical mountain." (DSB).

Order-nr.: 57427