Sliding Friction on Wet and Dry Sand

full article here:

ftp://213.176.96.142/aps8b0dfb6b-e773-20140502092553.pdf

We took "(How the Egyptians built the Pyramids)" out of the submitted title because it isn't in the article. The best way to add information like that is to post a comment to the thread.

There have been several previous posts about this theory. A previous discussion is at https://news.ycombinator.com/item?id=7687391.