Full Details

Name and Model Number Mast maker’s rule
Country of Origin UK
Date of Manufacture c1790 - 1870
Front Scales Coggeshall variant plus tables
Back Scales Tables of ratios of masts, spars and hull dimensions
Scale Length 11”
Type of Rule Other
Construction Boxwood & brass
Area of Use Other
Comment A 2-foot, 2-fold rule used for Shipbuilding calculations.
Mast maker’s or Ship’s Carpenter’s slide rules are perhaps surprisingly more common
than might be anticipated; however no two examples by a number of makers are exactly
the same. Examples with dimensions other than 2-foot, 2-fold are also known and this
is a splendid example by an un-named maker. Other examples are known from well known
makers such as Lorkin, Heather and Sampson Aston. These are an example of a slide rule
for a very specialist trade, how much such a rule would have actually been used in the
design and building of a square–rigged ship is not known.
Rarity RR
Donor Collection of an English gentleman
Match Number 59

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.