Full Details

Name and Model Number Routledge’s rule
Country of Origin UK
Date of Manufacture  c1805
Front Scales Routledge engineering (Soho) scales: D = 1 - 10
Back Scales Gauge points, conversion factors, circles, and pumping engine constants
Scale Length 11”
Type of Rule Other
Construction Boxwood & brass
Area of Use Other
Comment A 2-foot, 2-fold rule used for engineering.
Joshua Routledge’s slide rule is the father of the engineering 2-foot, 2-fold slide rules,
whereby sometime in the early 19th century, he took a Soho engineering slide rule and put
these scales on one leg of a folding slide rule, added an incredible collection of constants
applicable to engineering of all sorts, but particularly the design of steam engines, and so
the first of the engineering slide rules in this format was born. Virtually every folding rule
maker of any repute had a Routledge as part of their catalogue; examples such as this splendid
example from the maker Hotltzapffel & Co of London (1797 – 1914) included other engineering items
such as a protractor and spirit level.
Rarity RR
Donor Collection of an English gentleman.
Match Number 63

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.