Full Details

Name and Model Number Thomas Bradburn
Country of Origin UK
Date of Manufacture c1850
Front Scales A/B, B/C
Back Scales None
Scale Length 12"
Type of Rule Other
Construction Ivory/German silver
Area of Use Generic
Comment Routledge two foot folding rule with slide rule
Rarity RRRR
Donor Collection of Colin Barnes
Match Number 78

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.