Now HERE'S a real powerhouse, and an ultra uncommon rule in any variant. This is a photograph of Mr. Kay's MIB SIC 1580, a re-badged Ricoh 158, which was at the very top end of their rule catalog.
On the front side, a very "normal" hyperbolic rule, with hyperbolic sine and tangent scales, but also an odd BI scale (not normal on any brand, except maybe Faber-Castell...) and three log-log scales.
But the reverse isn't usual at all. You know what? I'd love to tell you that I know how to use all of the scales on this side of the rule. Love to. But I can't.. Because I don't.
Nonetheless, these are also exceedingly rare, in any variant. I couldn't even tell you which variant is the most common in the U.S.. |
