Not too sure about Barbour coming up with anything. His books really lacked.
1914 would be an easy date considering the daily head lines.
Russell borrowed everything and it is not like he prdicted anything.
As far as Jesus invisible presence came from Ellen White as there excuse for failure.
Pyramids was like a gold rush everyone was trying to discover new science because some famous English college was going to pay the winner money.
Pyramidology was rejected as a science. Laugh at!
People like Smyth was rejected and Russell agreed with Smyth writings then did his own.That is what I remember.
You can order the Chart to put on your wall. That will show you how crazy they were back then.
But if you read some of Rutherford's writings they are worse.
Considered the times Russell probably already had his dates outlined then placed them in some obscured book to make it appear like it was from God. How can you take a ruler apply years for each inch then go measure a pyramid come up with dates mankind. All made up.Although the nut did visit the pyramids.
He just banked that people were interested in reading anything about Egypt.