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Date: |
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Description: | 11 51542
5142
78 Grains P.15 1/2
ON OFF
Sir W Thomson's Patents no. 11529 REGISTERED KELVIN & JAMES WHITE Ltd GLASGOW
A zigzag compass received from the Board of Invention and Research.
Bowl-This is a pattern 14 Thomson compass bowl in the base of which a clockwork mechanism has been fitted. This mechanism drives a second lubber line backwards and forwards across the true lubber. By steering by this moving lubber line the ship would zigzag 45 degrees each side of her mean course with a period of eight minutes. The winding key ships in the base and a starting and stopping knob is fitted. Verge glass has an inverted cap.
Card- A 6? Kelvin card is fitted instead of the usual 8? for this bowl. It is not known if these compasses were ever used at sea. White with black markings graduated to 1/4 points and quadrantally in degrees. Paper rim attached to centre ring, into which jewelled cap fits, by radiating threads.
Needle-Four pin needles suspended by threads from card. 2 x 2.75" (7cm) 2 x 2.25" (5.7cm)
Pivot-Brass spike mounted in brass tube attached to zig zag mechanism.
caption: Record Shot - Do not reproduce. | Publisher: | "http://collections.rmg.co.uk/" | Rights holder: | "Royal Museums Greenwich" | Source: | Royal Museums Greenwich | Identifier: | http://collections.rmg.co.uk/collections... | Go to resource |
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