Schiehallion (pronounced shee-HALL-i-en, from the Gaelic *sidh chailleann*) is a mountain in Perth and Kinross, Scotland. It overlooks Loch Tummel and is 1,083 m high, which makes it a <<https://en.wikipedia.org/wiki/Munro|Munro>>. Seen from the west its shape is an almost perfect cone, and it is reasonably easy to climb with great views.

Being an isolated mountain with a very regular shape, Schiehallion was used in 1774 for an interesting experiment which was supposed to estimate the mass of the Earth by means of the deflection of a pendulum by the mass of the mountain. This experiment was proposed by Charles Mason (1728–1786, an English astronomer who was also instrumental in the definition of the Mason-Dixon line) and carried out by a commission under the direction of the Astronomer Royal, Nevil Maskelyne (1732–1811).

The intersection of the line of latitude midway between the most northerly and southerly points on the Scottish mainland and the line of longitude midway between the most westerly and easterly points is very close to the summit of Schiehallion. This means that in a sense the mountain could be seen as the “centre of Scotland”. This, however, presupposes that the most westerly point is Corrachadh Mòr in Ardnamurchan; the completion of the Skye Bridge in 1995 makes Skye technically part of the Scottish mainland and that would throw the calculation off.

The dance was originally devised in order to “create a new reel” (with “reel” as in “Scottish reel”, not “quick dance in 2/4 or 4/4 time” or “weaving formation”) during the early 1950s. It started out as a “self-assembly kit” which specified the “choruses” in strathspey time and reel time and left a choice of “verses” to the dancers. This did not go down well since most dancers preferred being told in definite terms what to do, so eventually Hugh Thurston picked the four most popular “verses” to arrive at the version of the dance done today. Its most popular figure was the “reel of eight” formation at the end, commonly called “Schiehallion reel” today, which Hugh Thurston originally thought was original but which is basically a version of the reel in the Orkney “Axum reel” as described by J. F. and T. M. Flett in *Traditional Dancing in Scotland* (the RSCDS version of the dance distorts this reel so that the correspondence is less easily perceived).
The original “self-assembly kit” publication of the dance is difficult to find today but the current version was published as a leaflet by Hugh Foss (Formby) in the early 1970s.
(**Update:** The current, ready-made, version now also appears in RSCDS <<ddpub:Book 53>>.)

Hugh Thurston describes the origin of the dance in <<link:thethistle/48||3>>.