Full Details

Name and Model Number Coggeshall-Dialling rule
Country of Origin UK
Date of Manufacture c1750?
Front Scales Timber Calculating scales note Girt Line
Back Scales Scamozzi sector lines
Scale Length 11
Type of Rule Other
Construction Boxwood and Brass
Area of Use Other
Comment a 2-foot, 2-fold rule.
Not sure of its area of use: perhaps this might be more architectural?
The unusual mixture of scales on the two sides of this early 2-foot, 2-fold slide rule
by an unknown maker are difficult to rationalise! The front appears to have the standard
suite of Coggeshall Timber and calculating scales aimed at calculating the volume of usable
timber in a standing tree, while the unusual sector scales on the back with unknown gauge
points may have something to do with calculating roof trusses but that is something I
would not set in stone! Part of the delight of these 2-2 slide rules is the unusual
combinations one finds, a Dialling and Routledge is also known, speculating what it was
used for or by whom, is interesting!
Rarity RRRR
Donor Collection of an English gentleman
Match Number 67

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.