Full Details

Name and Model Number Robinsonís 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 Robinsonís 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 Ĺ″ thick.
Rarity RRRR
Donor Collection of an American Gentleman
Match Number 58

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.