Hyperbolic Match Output
Maker:KEUFFEL & ESSER (USA)
Model:Log Log Vector No. 4093-5
Scales Front: || L, LL0, DF || CF, B, CI, C || D, LL3, LL2||
Scales Back: || Sh1, Sh2, Th || SI1&SI1, SI2&SI2, TI&TI || D, S, T || See C.M. - K&E Catalogs site
Gauge Marks: π is on B, CF, and DF; π/4 is on B; marks ' and ", and R are on scales C and D.
Construction: 20 in.; Plastic face on wood ; Cursor is framed. Adjustable metal brackets.
Date: 1934 - 1938
Source: Clay Castleberry Collection
Information: This is the first 20 inch sold with hyperbolic scales. (See C.M. - K&E Catalogs site).