Hi Sirfiroth,

I was just trying to refute the idea that the vertical height of the Grand Gallery was a mere estimate. Piazzi Smyth ordered a special measuring rod before he set out to Egypt knowing that it would be difficult to measure the vertical height of the Grand Gallery.

The height of the gallery reduces towards the higher southern end.

In addition there must be some variation, as you point out, due to the fact that the roof stones are tilted as a structural precaution.

I also expect there was some error of measurement as assistants were required to level the pole, clamp it etc - only one measurement was repeated 970 inches up the slope and the reported measurements were 341.3 and 339.0 - it seems Piazzi Smyth thought this was close enough and didn't repeat any other measurements - but he measured so much so quickly and knew he had only four months and perhaps had other priorities.

The mean of 16 measurements was 339.5 inches, but the masonry at the higher south end of the gallery is relatively poor. The precise height at the south end may not have mattered as much, or may be there is a different symbolic height related to the Great Step.

Don't forget there was no powerful electric lighting in 1865, but Piazzi Smyth noted that the angle of the stones was by no means constant - it was particularly marked at the fourth, seventh and tenth from the north (4 x 7 x 10 = 280?). From memory Piazzi Smyth commented that the light from the torches of Arabs was less than ideal when trying to see the roof of the Grand Gallery.

Petrie measured the height to the bottom of the groove as 172.1 inches near the north end wall, and took this as the half-height of the gallery from Smyth's measurement of 344.2 inches - 2 x 172.1 = 344.2 inches. In my model the bottom edge of the groove is the half height of the gallery.

There is a slight error in Petrie's calculation of the height of the groove. It is reported as 166.2 + 5.9 = 172.1 inches, where 5.9 inches is the mean of 4 measurements taken at NE, NW, SE, ans SW. In reality he should have used the measurements near the north wall which were 5.4 and 5.7 inches perpendicular (6.0 and 6.4 vertical), so the height is between 172.2 and 172.6 from Petrie's measurements with a mean of 172.4.

From Petrie 2 x 172.4 = 344.8 inches.

20.61 inches / royal cubit x sr280 royal cubits = 344.9 inches

I think that the height at the higher end of the gallery was intended to be less, but explaining why is another topic.


Mark

PS see my recent new topic post on number 9 in the grand gallery, although this is not, as far as I know, related to the south end of the gallery.



Edited 1 time(s). Last edit at 10/31/2011 01:43PM by Mark Heaton.