across it, and then to cause a piece of twine with a blob of clay on the end to swing like a pendulum 366 times during that period. From fulcrum to the centre of the blob was a mathematically perfect 1⁄2 Megalithic Yard or twenty Megalithic Inches. The process was simple to carry out and works on the fact that a pendulum is responsive to only two factors: the length of the pendulum and the mass of the Earth. If the pendulum beat 366 times during the transit of Venus across a 366 th part of the sky – you had your measure! (See Appendix 1 for a more detailed explanation of the pendulum method.)
It is doubtful that these ancient stonemasons realized the fact but the period of time that they watched Venus and elected to subdivide into 366 beats, is equal to the difference between a mean solar day and a sidereal day.
Our starting point had been to search for all possible sources of reliable measurement available from nature. And we found that there was only one: the turning of the Earth on its axis as seen by watching the movement of the heavens. It was possible to time the passage of a star, or in this case the planet Venus, with reliable accuracy using a pendulum. The pendulum then turned a unit of time into a unit of length because the timed beat will always produce a fixed length – with tiny variations due to latitude and altitude.
It was then a simple matter to turn a unit of length into a measure of volume and capacity by creating cubes and filling them with liquid or dry goods such as barley or wheat. However, we were not prepared for the shock we received when we created a cube with sides of four Megalithic Inches and found that it held a pint that was accurate to a staggering one part in 5,000 against the standard laid down in the year 1601. Doubling the sides to eight Megalithic Inches produced an accurate gallon and doubling again produced the old dry measure known as a bushel. The mystery was compounded when we filled the ‘pint’ cube with barley and found that it weighed exactly one pound!
Things turned from the sublime to the ridiculous when further experimentation showed that a sphere with a diameter of six Megalithic Inches held virtually one litre and one ten times the size weighed a metric tonne when filled with water; all to an accuracy of better than 99 per cent.
The fact that Thom’s apparently meaningless Megalithic Yard, extracted from surveying hundreds of prehistoric ruins, produces these cubic and spherical feats is not debatable. No one, no matter how sceptical they might be, can deny the simple maths. Neither can they deny that the odds of such compounded apparent connections being coincidence are very high. Yet, the pound and the pint are thought to be Medieval and the litre and the tonne were invented at the end of the eighteenth century.
A connection seemed impossible.
Then we looked at the Sumerian people who lived in the region we now call Iraq some 5,000 years ago. They are attributed with inventing writing, glass, the wheel, the hour, minute and second of time as well as the 360-degree circle with its subdivisions of 60 minutes and 60 seconds of arc. Quite amazing people.
As we probed the achievements of this civilization we found that the unit of length the Sumerians had used was virtually a metre at 99.88cm and that they had also used weights and capacities that were as equally matched to the kilo and litre of the French metric system created thousands of years later. Quite a coincidence we thought – but it was nothing of the kind, for when we applied the principles of the pendulum to the Sumerian unit of length called the ‘double kush’ we found that a pendulum of this length beat at the rate of one per second. This meant that the Sumerian’s key unit of length and their key unit of time were two sides of the same coin when used as a pendulum. A double-kush pendulum would always beat out a second and a pendulum that beat at the rate of a second would always be a double