Full Details

Name and Model Number	Gebr. Wichamann Model 1399
Country of Origin	Germany
Date of Manufacture	~ 1914 – 1930?
Front Scales	L.C/D,√,√(2 circles)
Back Scales	Tan,C/R,3√ (3 circles)
Scale Length	Approx 16cm.
Type of Rule	Watch Type
Construction	Metal with celluloid lenses, rotated using the thumb
Area of Use	Generic
Comment	Quite idiosyncratic version of the Calculex with a pocket-watch winder to rotate the centre scales on both sides
Rarity	RRR
Donor	Collection of Peter Hopp
Match Number	43
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RR	= Rare -- 1 of 25 collectors has one; it may take a year to find an example in the marketplace.
RRR	= Very rare -- only very few known to collectors; may take several years before one comes up for sale.
RRRR	= Extremely rare -- a museum piece; unlikely that an example will ever come up for sale.