Pic is of an Edwards production of the McLeod gauge for measuring vacuum.
It needs some restoration work, and in preparation for doing that I find that there does not seem to be ANY online scan or text of whatever original manual Edwards sold with these gauges. Not even a single photo of it.
What I want is an original paper copy of that manual, either to buy or borrow. So I can scan it and put it online.
The McLeod gauge is still a very useful thing, for calibrating mechanical vacuum gauges. And the online pages about using it are pretty poor.