Dear Stephen, Many thanks for your letter and interesting enclosures. I am glad that you have now found someone to work out the vanishing point of the Giza Pyramids in three dimensions, since I would hesitate to attempt this calculation myself. To find the intersection of the ground circles in a horizontal plane, is not too difficult, but to relate the apex circle to the ground circles  if these are to pass through the actual corners of the pyramids at their different levels  is a different proposition... The only information I have about the different levels of the pyramids is that contained in the survey by the civil engineer J,S. Perring, which he published around 1840 in a volume of large plans of the pyramids. The same data is given by Howard Vyse in 'Operations carried on at the Pyramids of Gizeh in 1837' (Vol.II p.106), as follows: Base of Second Pyramid above base of Great Pyramid 33
feet 2 inches If you ever come across any more modern data than this, or decent contour maps of the Giza plateau, please let me know! I'm still involved with the pyramids and always interested to learn of other peoples' opinions on the subject. So don't hesitate to inform me of the outcome of Aaron Landy's investigation.
