Schiehallion

Schiehallion (; Scottish Gaelic: Sìdh Chailleann, IPA: [ʃiˈxaʎən̪ˠ]) is a prominent mountain in Perth and Kinross, Scotland. Schiehallion has a rich botanical life, interesting archaeology, and a unique place in scientific history for an 18th-century experiment in "weighing the world". The mountain's popularity amongst walkers led to erosion on its footpath and extensive repairs were undertaken in 2001.

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.