n
In the early seventies and eighties when I was in college there were
no calculators. At least not the hand held varieties. We had to use
slide rules. In most General Chemistry classes the semester started
out with lessons on how to use a slide rule. To do this a very large
slide rule, about six feet in lenght and 1.5 feet in length was hung
over the blackboard and the professor used it to demostrate to
students slide rule techniques. They worked the same and where just
as accurate as the small hand held models. Perhaps if you call some
local universities they may have one, forgotten and in storage some
where.