Supposed standard unit of measurement used in the construction of the Great Pyramid. In 1864 Charles Piazzi Smyth, Astronomer Royal of Scotland and a professor at the University of Edinburgh, published a book entitled Our Inheritance in the Great Pyramid. In it Smyth proved to his own satisfaction that the Great Pyramid of Egypt was based on a divinely inspired unit of measurement he called a pyramid inch. Smyth’s work has become a staple of pyramidology, and the pyramid inch has been used to measure the distance from Earth to the sun, Earth’s density, and its mean temperature.
Smyth discovered that when he divided the length of the base of the Great Pyramid by the width of a casing stone the stones that originally lined the exterior of the pyramid he got 365, the number of days in the year. The Edinburgh professor defined the length of the casing stone (about 63 1/2 centimeters [25 inches]) as the biblical cubit. He found that by dividing the width of a casing stone by 25, he got a unit that was only a little larger than the standard inch but was also 1/10,000,000 of the distance from the middle of Earth to the North Pole. In 1865, Smyth traveled to Egypt to confirm his conclusions by making his own measurements of the Great Pyramid. He published his results in Life and Work at the Great Pyramid (3 volumes, 1867) and On the Antiquity of Intellectual Man (1868).