| Name and Model Number | Robinson’s Calculator |
| Country of Origin | UK |
| Date of Manufacture | c1926 |
| Front Scales | D scale and table of weaving constants |
| Back Scales | None |
| Scale Length | Approx 8.6″ (21cm.) |
| Type of Rule | Watch Type |
| Construction | Metal |
| Area of Use | Other |
| Comment | Used for Textile calculations.
Frederick Robinson’s Calculator was the subject of a 1926 UK Patent No. 256,903 jointly with the Lancashire Optical Manufacturing Company of Manchester, for a calculator for cotton cloth. The resulting calculator, made by an unknown maker, has unique knurled circular discs which protrude from the side for rotating pointer and scales appropriately to perform calculation using the fixed and movable pointers and the rotatable scale. Only one example of the calculator is known, it is 2⅞″ diameter and ½″ thick. |
| Rarity | RRRR |
| Donor | Collection of an American Gentleman |
| Match Number | 58 |
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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. |