Hyperbolic Match Output
Maker: ADF Products (USA)
Model: ADF 103 Engineer's Semi-Circular Slide Rule
Scales Front: || D, L, DI, S, T, ST, K, R, LL3, LL2, LL1, LL01, LL02, LL03, TH, SH2, SH1, LL0, LL00 ||
Gauge Marks: π is on D, DI, K and R.
Construction: 8.3 cm. radius (3.27 in.), Aluminum, Two Cursors, This is one-half of a circular Slide Rule
Source: Ed Chamberlain Collection
Information: Patented September 5, 1961 by Arthur D. Frankenfield, U.S. Patent No. 2,998,916