Hyperbolic Match Output
Maker:PICKETT & ECKEL (USA)
Model: 4-T Dual-Base Log Log Reciprocal Scale (Vector Hyperbolic)
Scales Front:||Three cube root scales 3√, DF|| CF, T&T, ST, S&S, CI, C || D, DI, Two sqrt scales √ ||
Scales Back: || LL1&LL1, LL2&LL2, DF || CF, Th, Sh&Sh, L, CI, C || D, LL3&LL3, LL4&LL4 ||
Gauge Marks: π is on C, D, CF, DF, CF/M, DF/M, CI, DI, CIF ; R and π/4 are on C & D; marks 1° , ' and " are on ST.
Construction: 25 cm.; White film over Aluminum, Cursor is not framed, Adjustable metal brackets.
Source: Herman's Archive
Information: Same rule but different colors as Model 4-ES Dual-Base Log Log Reciprocal Scale (Vector Hyperbolic) which has a yellow plastic film over Aluminum.