Union Instrument Co., No. 2050 Air Force Aerial Photo Rule Type A-1

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Country of manufacture: USA,            Date of manufacture: ____
Overall length: 30.2 cm,          Width: 3.8 cm,           Weight: 98.9 gms
Materials: all aluminum, adjustable
Cursor: 2.6 X 5.1 X 0.6 cms; plastic runners holding plastic lens; metal edges to runners, adjustable; lines = single line front and back
Scales: 16, including some specialized on back
Front: L, A, DF [ CF, CIF, T, S, C ] D, DI, K
Back: Ground size, Ground Speed [ Image Size (cm), Image Size (feet), Focal Length ] Altitude
Gauge Marks: [ π, R ]
Condition: C2-C3 (Mint to very minimal signs of use)
Came with: Original black plastic and leather case w/snap closure
Notes: This is clearly an Art Eckel design, perhaps made for Union Instruments by Precision Scale Company after he split from Pickett & Eckel?

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Expanded view of outer metal runner edge (top and bottom edges of cursor are the same):

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