 The Schiehallion experiment was an 18th @-@ century experiment to determine the mean density of the Earth . Funded by a grant from the Royal Society , it was conducted in the summer of 1774 around the Scottish mountain of Schiehallion , Perthshire . The experiment involved measuring the tiny deflection of a pendulum due to the gravitational attraction of a nearby mountain . The experiment was designed by Charles Mason and Jeremiah Dixon , who had previously surveyed the boundary between Pennsylvania and Maryland . The experiment was conducted by James Bradley and Nathaniel Bliss , and the results were published in 1776. sierpniu 1774, Mason and Dixon