| 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 |
| Thumbnail |  |
| 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. |