Full Details

Name and Model Number Froude Displacement Rule
Country of Origin England
Date of Manufacture ~1902
Front Scales X3/X3 X/X Displacement, Length,K, Speed
Back Scales X2/X2 X/X Scale, Knots, Ft/m
Scale Length 62cm
Type of Rule Slide Rule
Construction Box, closed frame, brass blade cursor
Area of Use Other
Comment Used for ship hull designase leave blank.
Rarity RR-RRR
Donor Collection of Peter Fox
Match Number 50

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.