Ahatmose, in all his excitement, has somewhat misconstrued what I wrote.

The figures for the latitudinal decrease to the position of the Tropic of Cancer during the early Dynastic era are given as 1/10,000th part of latitudinal degree per year (36.3688 feet at the latitude of Giza) with occasional years of latitudinal stability: in 2551 BC during the construction of the Khufu, subsequently 27 years later in 2524 BC during the construction of the Khafre – then 29, then 33 years later, etc.. (https://data.giss.nasa.gov/cgi-bin/ar5/srorbpar.cgi)

Hence, the specific annual decrease to the latitude of the Sun Eye (what I have termed the "specific Stride of Re") remained constant at 36.3688 feet, whereas the average annual decrease, (the "average Stride of Re") which takes into account the years of recorded latitudinal stability, always increased during the Pyramid Age, from ~34.08 feet per year during the construction of the Djoser, to ~34.47 f.p.y. during construction of the Menkaure (2487 BC – 2478 BC).

The Egyptian Royal Cubit derived from a twentieth part of the average Stride of Re, hence the length of the cubit increased over time: from an equivalent of 20.5482" at the Bent Pyramid, to 20.6123" at the Khufu, to 20.68" at the Menkaure. If one knows the cubit value employed, which the architects went to ingenious lengths to specify, the chronology of each Old Kingdom Pyramid is calculable.

Reason for the length of the King's Chamber was to specify the average latitudinal decrease to the position of the Sun Eye during construction of the Khufu, also why the KC was located E – W in length, to specify the year of latitudinal stability in 2551 BC, when the KC lay at 6 degrees of latitude above the position of the Tropic. As with the E – W length of the Subsidiary Chamber of the Khafre: whereas the "Burial Chamber" of the Menkaure was positioned N – S in length, to relate no year of constancy to the Tropic's position during its construction era.

The latitude of the Tropic of Cancer lies at the root of the formulation of the Egyptian Civil calendar, and the lengths of the specific and average Strides of Re lie at the root of the design measures of every royal Pyramid of Egypt, from the Djoser to the Ahmose.

For a synopsis of the origin of the Royal Cubit, the increasing velocity to the southward travel of the latitude of the Tropic, and the measures employed in the constructions of the Pyramids of the 3rd and 4th Dynasties –

See pgs. 229 – 259

The Pyramids of Giza – Exact Chronologies and Significance

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