Schiehallion, Perthshire

Mathematical Gazetteer of the British Isles

Schiehallion (or Schiehallien or Schehallien) is an isolated conical mountain (or narrow ridge??), 3554 ft high, in Perthshire (now Perth & Kinross), about 20 km west of Pitlochry. In 1772, the astronomer Royal, Nevil Maskelyne, asked the Royal Society for advice and they appointed a Committee of Attraction (with Maskelyne and Cavendish as leading members) to advise on how to determine $G$ from the deflection of a plumb line (or pendulum) near a mountain. This was the mountain selected and Maskelyne carried out observations here in 1774-1776 (or Jul-Nov 1774). The calculations were carried out by Hutton (following suggestions of Cavendish) and found that the density of the Earth was about 4.48 (later revised to 4.713, still much too low) - see [1] and a similar paper of 1821. Maskelyne was awarded the Copley Medal of the RS for this work. It is claimed that one of the surveyors, named Hutton (the same one??), invented contour lines during the associated mapping. (However Halley used isogonal lines in a map of magnetic variation in 1702.) There is a plaque in the car park in the Braes of Foss. [2]; [3]; [4]; [5]
See THIS LINK

Playfair investigated the rocks of the mountain in more detail in 1811 leading to a further revision to 4.87. [6] See Edinburgh.

References (show)

1. Hutton, Charles. Mean density of the earth, Phil. Trans. 1778
2. Mackinnon, Nick. Mountaineering Mathematics. Mathematics in School 16:2 (1987) 20-21.
3. Proctor, Richard A. Weighing the earth. Knowledge 11 (Apr 1888) 123-125 & (May 1888) 151-153.
4. Anon. Memoir of the late Dr. Hutton. Gentlemen's Magazine and Historical Chronicle 93 (Mar 1823) 228-232.
5. Stewart, J. J. Weighing the earth. Knowledge (1 Feb 1894) 30-32 & (2 Apr 1894) 88-89.
6. Berry, A. J. Henry Cavendish His Life and Scientific Work. Hutchinson, 1960. pp.163-164.

The Mathematical Gazetteer of the British Isles was created by David Singmaster.
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