Fowler's "Twelve Ten" Calculator
Description
Circular slide rule.
Scales: Tenths, Recips, Twelfths, Twelfths, sines, sines, tans.
Dark brown leather case with top flap.
Circular slide rule.
Scales: Tenths, Recips, Twelfths, Twelfths, sines, sines, tans.
Dark brown leather case with top flap.