The Schiehallion experiment was repeated in 1856 by Henry James, director-general of the Ordnance Survey, who instead used the hill Arthur's Seat in central Edinburgh. With the resources of the Ordnance Survey at his disposal, James extended his topographical survey to a 21-kilometer radius, taking him as far as the borders of Midlothian. He obtained a density of about 5,300 kg·m−3.An experiment in 2005 undertook a variation of the 1774 work: instead of computing local differences in the zenith, the experiment made a very accurate comparison of the period of a pendulum at the top and of Schiehallion. The period of a pendulum is a g, the local gravitational acceleration. The digital pendulum is expected to run more slowly, but will act within the hill Arthur's Seat in central Edinburgh. With the resources of the Ordnance Survey at his disposal, James extended his topographical survey to a 21-kilometer radius, taking him as far as the borders of Midlothian. He obtained a density of about 5,300 kg·m−3.
5 300 kg·m−3