Glossary X
At a lunar backsight where permanent or temporary ancillary extrapolation gear has been set up there should be a length preserved between major stones which is the 4G for this site. This 4G represents, on the ground, the lateral distance an observer must move in order to 'shift' the Moon through the declination range K. K is the change in the Moon´s position during the 24 hours preceding a standstill. At a Major Standstill it is 46.5 arc minutes and at a Minor Standstill 30 arc minutes. See also- K, ANGULAR DISPLACEMENT, EXTRAPOLATION PROCEDURE, LUNAR STANDSTILL.

Megalithic Study Sites

Thumbnail of Ballochroy
The most definitive summer solstice site identified by Alexander Thom must be the stone row at Ballochroy, North Kintyre. This dramatic stone row sits on the mainland hillside overlooking the Sound of Jura with it's central stone, a large blade or cleit, having it's two long faces clearly aligned on one of the high peaks, Corra Bheinn, on the mountainous island of Jura to the north west. From these stones, at the summer solstice of 1800 BC, (according to Thom's theodolite surveys), the upper limb of the solar disc, at sunset, would first graze the top of Corra Bheinn then slide down the long north flank before settling into the notch at the foot of the mountain. This demonstrates that the...