Full Details

Name and Model Number Lord's Calculator
Country of Origin England
Date of Manufacture  
Front Scales D [C][B] A
Back Scales  
Scale Length 7.0 cm diameter
Type of Rule Watch Type
Construction Nickel plated brass
Area of Use Generic
Comment Manufactured by R. Waddington.
Used for weaving.
Rarity RR
Donor Collection of Rod Lovett
Match Number 21

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.