Goyon measured his layers up the North East corner and claims an accuracy of plus or minus 5mm. A wider tolerance than Petrie. He is of the opinion that averaged out over the 200 or so layers that errors in one direction will cancel out those in the other. So difference between his and Petrie's measurements only become significant when they are greater than Goyon's margin of error.

He arrives at a total for the height of the remaining layers of 5462.4 inches (my conversion of his metric figure) compared to Petrie's of 5452 inches.

I used Petrie's "mean" figure which he produced by averaging his measurements for the North East corner and the South West corners.

Because Petrie combined two sets of measures I think his figures have to be given more weight.

Petrie certainly did make copying errors according to Graham Oaten who compiled the web based version of his survey. I still think there's something odd somewhere in the figures but I'll do the comparison again using just the data from the North East corner from both authors and report back.

I've got a set of scans of Petrie's original notebooks from his time at Giza and they are a nightmare to try and decifer. His writing is appauling and he crams things in all over the place along with scribbled drawings. I haven't been able to identify his measurements for the layers but they might be in there somewhere as the whole lot is a bit of a mess.

Jon

www.egyptarchive.co.uk