Anybody who neglects the survey of Perring, neglects it at their peril, which Petrie did to some extent.

It is, however, certain that the slope became less steep near the top of the lower section for the east and west sides, although the north and south sides are quite uniform.

Some, including me, think that the Petrie looked at things in rather too much detail, for example, measurements reported to 1/100 inch at the Great Pyramid. I note that some then build theories on Petrie's measurements, and show that the theory is exact, as if there was no build error or change in the structure after thousands of years.

Perring does report the slope to a very precise angle, rather too precise for my liking, but now clearly seen as the seked of 5 palms, even though Perring was not aware of the seked as a unit of slope.

The survey by Steve Burrows was a structural survey. The laser instrument was designed to detect structural anomalies, searching for deviations from a flat plane, and is not easy to form an opinion on the results (as he said). We were guided to a simple conclusion by the graphic presentation of results. I don't doubt the integrity of Steve Burrows, or his conclusion that there was no inward subsidence, which is what he was looking for.

From memory, I think Steve commented on the level of the bend as a couple of hundred feet above him. If so, then this was a fair statement, as it was an eye assessment in the knowledge it was far more than one hundred feet and far less than three hundred feet. From Petrie the bend was at approximately 155 feet. There is a big difference between a structural engineer interested in the integrity of a structure and a surveyor interested in recovering original dimensions precisely.

You mention the latest survey of Dorner. There have been several surveys since the nineteenth century, and these are not easy to reconcile. I am content that the surveys of Perring and Petrie are in close agreement, and note that the pollution of the industrial age may be changing the size and shape of the pyramid. 'Acid rain' dissolves limestone rapidly. Cleopatra's needle in London has suffered more damage there than in all the preceding centuries.

It is probably very difficult for modern surveyors to get the same access as Perring and Petrie. A long distance laser view sounds wonderful, fit for purpose, but can this really be a substitute for close-up work? The many thousands of measurements give a three dimensional surface image, but the actual surface is far from even, because the casing stones are present in some places and not in others. Steve Burrows mentioned the difficulty in interpreting the results. His eyes were fixed on determining a structural problem, which he hoped to find, and it is to his credit that he fixed his mind on resolving the laser data correctly, and not on his initial impression of a structural problem.

Can the laser survey data gives us the precise slopes all around the Bent Pyramid from top to bottom?

Mark



Edited 1 time(s). Last edit at 01/16/2015 03:41AM by Mark Heaton.