product/user manual

[AL2]

I recently acquired an old Gilson circular slide rule, Gilson no longer exists and circular slide rules, like the conventional type are no longer made. In any event, this particular circular slide rule is a Gilson Atlas 8"/21cm model. It has trig scales and decimal equivalents on one side, with a single arm. The other side has 2 arms, Atlas Spiral Scales with which the user can solve numerical problems, and obtain logarithms to 5 decimal places if desired. My old HP 11C can do more, a lot more, but I'm curious re this circular rule.

The slide rule came without any sort of manual. I found a brief sketchy explanation on the Internet, but would like to obtain a more detailed explanation if such is available. Any suggestions or direction appreciated. Thanks in advance.