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Frederick Post Co. 1450 Versatrig

• 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)