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Pickett Model 4 Deci Log Log Vector Hyperbolic

• Type: Log Log Duplex
• Size: 11 Inches / 27 cm
• Material: Magnesium
• Scales:
  • Front: 1/N₁ 1/N₂ 1/N₃ 1/N₄ DF [ CF Th Sh Sh CI C ] D/Co N₁ N₂ N₃ N₄
  • Back: ∛ ∛ ∛ DF [ CF T ST S CI C ] D DI √ √
• HvH: 5015

With rubber case. This rule was made between 1947 and 1962, most likely toward the beginning of that period. Serial number on runner, "C033544". To the scales on the Model 2, are added a DF scale and hyperbolic trig scales. To make room, the Model 4 removes the L scale and the second T scale for angles larger than 45º.