Wasn't our understanding of how the pyramids were built, particularly the great pyramid, still very much up for debate until modern times? Let alone 1893? Plenty of older theories have been debunked.
It's an interesting subject no doubt but a more modern source would likely be a better use of time.
Noticed the newest book on Project Gutenburg is:
A HISTORY OF ARCHITECTURE IN ALL COUNTRIES, FROM THE EARLIEST TIMES TO THE PRESENT DAY.
By JAMES FERGUSSON, D.C.L., F.R.S., M.R.A.S., FELLOW ROYAL INST. BRIT. ARCHITECTS,
So I click on it, and the very first building is the Great Pyramid, complete with diagram: https://www.gutenberg.org/files/55870/55870-h/55870-h.htm#Pa...
1893.