Full Details


Name and Model Number Dempster RotaRule
Model AA
Country of Origin USA
Date of Manufacture 1928 - 1949
Front Scales K, A, D [C, CI, CIF, S, C, ST, T, CT, G (2 scales), B, F/i]
Back Scales L, LL%, LL1, LL2, LL3, C [V1, V2, DLL, D]
Scale Length 50" (127 cm)
Type of Rule Disc
Construction Plastic. 5¼" (13 cm) diameter
Area of Use Other
Comment For precision basic math and stadia calculations.
Has unique modified spiral scales.
Rarity RR-RRR
Donor Collection of Rod Lovett
Match Number 47
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In conjunction with our 'donors' we assign a rarity rating to each item, based on the system devised by Herman van Herwijnen
(1929 - 2004), renowned Dutch collector, author, and creator of Herman's Archive, a collection of 5,000 slide rule images on CD.
• RR = Rare - 1 of 25 collectors has one; it may take a year to find an example in the marketplace.
• RRR = Very Rare - only a few known to collectors; may be several years before it comes up for sale.
• RRRR = Extremely Rare - a museum piece; unlikely that an example will come up for sale.