Alexander Thom
As early as 1934 Alexander Thom had become interested in prehistoric stone circles and their astronomical associations, and published an article in 1951 in the Journal of the British Astronomical Association entitled "The solar observations of megalithic man."
Thom began accurately surveying and carefully measuring megalithic sites throughout Britain, the initial results of which he published in 1955 in the Journal of the Royal Statistical Society. After his retirement, he published two more articles in 1962 and 1964.
His discovery of what he called the megalithic yard (2.72 feet, or 0.83 metres), a unit of measurement he found at many prehistoric megalithic sites, is a key feature of his book Megalithic Sites in Britain, published in 1967, for which he had surveyed some 300 megalithic circles, alignments, and isolated standing stones. This was followed in 1971 by another book, Megalithic Lunar Observatories.
Besides the megalithic yard, Thom also categorised stone circles, showing there were six geometric types: true circles, ellipses, two sorts of egg-shaped circles, and two sorts of flattened circles.
In important ways, Thom's work converged with that of Gerald Hawkins at Stonehenge, which also linked it with astronomy and mathematics. Whereas Hawkins focused on Stonehenge, Thom was able to demonstrate that a large number of other megalithic sites were also oriented to the sun and the moon.
Although admired for his impeccable science and respected for the thoroughness and intellectual rigour of his research, Thom's findings remain controversial among scholars.
