Post 1450

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Frederick Post Co. 1450 Versatrig

Obverse
Obverse
Reverse
Reverse
  • Type: Trig Duplex
  • Size: 10 Inches
  • Material: Bamboo and celluloid
  • Scales:
    • Front: K DF [ CF CIF CI C ] D R1 R2
    • Back: L A [ T ST S C ] D DI
  • HvH: 3757

Popular trig rule. T scale reads 5.7 to 45 degrees against C or D, 45 to 84.3 against DI. ST also marked "Sec T" in red. This is confusing, as you would read the secants of the red figures against the C scale, and the sines against the DI scale. S scale co-marked "Cos".

Dated October 1961 ("LJ" mark on lower edge)

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