Full Details

Name and Model Number Gebr. Wichamann Model 1399
Country of Origin Germany
Date of Manufacture ~ 1908 – 1914?
Front Scales L.C/D,√,√(2 circles)
Back Scales Tan,C/R,3√ (3 circles)
Scale Length 65 mm diam, approx 16cm.
Type of Rule Watch Type
Construction Metal with celluloid lenses, rotated using the thumb
Area of Use Generic
Comment Wichmann’s original slightly larger version of the Calculex,
later replaced by their similarly numbered model with a
pocket-watch winder – see Wichmann2
Rarity RRRR
Donor Collection of an unknown gentleman
Match Number 42

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.