B. F. Grizzle Orifice Meter Calculating Rule

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Country of manufacture: USA (probably Lawrence Engineering),            Date of manufacture: ____
Overall length: 21.3 cm,          Width: 2.9 cm,           Weight: 25.1 gms
Materials: painted wood
Cursor: 2.3 X 3.0 X 0.6 cms; Metal framed plastic lens; lines = one on front
Scales: 6, specialized
Front: Extension Scale A, B, Vacuum Gauge Pressure Scale [ Differential Scale, Correction Scale, Coefficient Scale (4-part) ] Cubic Foot Scale (4-part)
Back: Data tables for calculations
Condition: C4 (Minimal signs of use), some age-related discoloration
Came with: faux-leather black pocket slip case, instructions

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