Full Details

Name and Model Number Dialling rule
Country of Origin UK
Date of Manufacture c1750
Front Scales Calculating scales
Back Scales Scamozzi sector lines
Scale Length 11
Type of Rule Other
Construction Ivory & German silver
Area of Use Other
Comment A 2-foot, 2-fold used for the layout of vertical and horizontal sundials.
Dialling, or "New Improved sliding rules" with their pair of adjacent very thin slides,
are amongst the most unusual 2-foot, 2-fold slide rules. This delightful ivory and German
silver example with small square hinge by Wood & Lort of Birmingham (1750 1760) carries
the full range of scales, the bottom of the two slides allowing a calculation with a pre-set
calibration off-set found on the bottom edge. It is thought that the design came from the
English mathematician John Browne, and it could also be used for navigation.
Rarity RRRR
Donor Collection of an English gentleman
Match Number 65

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.