The Cailleach Bheur of Schiehallion

Schiehallion, Perthshire, Scotland

Schiehallion — the 'fairy hill of the Caledonians' — is the Highland seat of the Cailleach Bheur, the blue-faced hag of winter storms still blamed for sudden squalls on the mountain.

Schiehallion's name comes from the Gaelic Sìdh Chailleann, "the fairy hill of the Caledonians," and the mountain has long been associated with the Cailleach — the divine hag of pre-Christian Gaelic tradition, who in this region takes the specific form of the Cailleach Bheur, the blue-faced winter hag of Highland folklore. The Cailleach Bheur was described by 19th-century collectors of Rannoch folklore, notably A.D. Cunningham, as an old woman with a face blue with cold, hair white with frost, and a plaid grey as winter fields, who rode the storms and dealt out sudden, killing cold to travellers unlucky enough to be caught on the mountain when she passed. Local tradition held her responsible for the abrupt weather changes Schiehallion is still known for — a clear morning turning to whiteout in the time it takes to reach the summit ridge — and older Rannoch families warned against climbing the mountain without leaving some small offering at its foot. The mountain has one further, more scientific claim to fame: in 1774 it was the site of the Schiehallion experiment, in which the astronomer Nevil Maskelyne used the mountain's regular, isolated shape to measure the gravitational deflection of a plumb line and calculate the mass of the Earth — one of the first successful attempts to weigh the planet. Locals at the time noted, with some satisfaction, that the surveyors chose to make camp well down the slope, and were in no hurry to be caught out after dark.