In 1924 an English engineer J. Tarrel had observed that the thick foundations at the beginning gradually decreased in height to a level from which there was an increase, followed by a further reduction in the thickness of the courses and so on. He thus counted 18 slices or groups of assizes to the summit (The Great Pyramid Races Anc Eg. 1925, II p.36-38). Goyon also found 18 groups of assizes. It should be noted, that the heights of the seats do not decrease regularly and that the slices are formed by an unequal number of seats. On the other hand, there has been no discovery of any mathematical order in the decrease of numbers: the heights of the seats do not diminish regularly, and the slices are formed of an unequal number of seats. Tarrel thought that, as preliminary work, the stones necessary for the construction of the pyramid had been accumulated for 10 years and spread over « hundreds of acres ». Goyon thinks that this mode of construction is a technique related to the nature of the soil from which stones of the pyramids were extracted. Tarrel and Goyon should be partially right.
Cheops pyramid 