Slide rule

Slide rule for calculating level errors. Slider marked "POSITIVE" "NEGATIVE". On either side of the slider are the fixed pieces. One is marked "ABOVE THE POLE" and then on another part of the same piece it is marked "SCALE OF CORRECTIONS OF TRANSITS IN SECONDS OF TIME FOR LEVEL ERROR IN SECONDS OF ARC LATITUDE 51 degress 28' 39'' NORTH". The other fixed piece is marked "BELOW THE POLE" and elsewhere on the same piece, 'STARS NPD BELOW THE POLE". The back of this slide rule is blank.

Object Details

ID: ZBA0636
Type: Slide rule
Display location: Not on display
Creator: Troughton & Simms
Date made: circa 1850
People: Troughton & Simms; Royal Greenwich Observatory Airy, George Biddell
Credit: National Maritime Museum, Greenwich, London
Measurements: Overall: 8 mm x 620 mm x 153 mm
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