Long’s business (posthumous) was at this address from 1885 to 1936.
Marked with the broad arrow for the UK government and ‘Pattern 1448’. A pice of celluloid is missing from the back and the metal indicator is missing from the end of the slide. It dates from 1943 and other rules are known from this date with this cursor, possibly a wartime economy measure. Like the rule above it has a plain lacquered mahogany back, typical of the 5 inch wooden rules. Thornton PIC Electrical and Mechanical Engineer’s Rule.
These may include Boxwood, Ivory (Bone), Brass and in many instances were hand-divided by an artisan.
Thanks to the members of the UK Slide Rule Circle, the Dutch KRING and the Oughtred Society for most of the scans provided in this gallery. Many of these images in the ISRM galleries, also appear in the Oughtred Society's Rarities Gallery, which displays rare, not necessarily old, specimens in collections of active members's of the Oughtred Society.
It is a “Proof” slide rule for the calculation of percentage proof and is one of two types of slide rule for use with the Sikes hydrometer.
Alcohol slide rule by Joseph Long, 43 East Cheap, London.
Search for farmar dating:
Farrow & Jackson Ltd, London, spirit slide rule, probably ca.1900. This is the other type of slide rule found with Sikes hydrometers and is a “Comparative” slide rule.