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Description: | P.Lealand London
Upper Bowl-Brass with black centre. Graduated in Roman and Arabic numerals I-XII and 1-12 around edges. Altitude sighter which swivels at centre of bowl. Thumb screw rack and pinion adjustment for altitude, arc is graduated 0-45 twice. Small vernier on side of arc and sights on top. An arrow lies across the bowl pointing at the graduations. Bowl can be adjusted horizontally by rack and pinion which moves an arc graduated to 90 degs. This also has a vernier. Lead weight slung beneath bowl. The whole set in gimbals.
Compass bowl-Brass, white metal inside. Glazed. Slung beneath lead weight of upper bowl by three brass tubes. Graduated to eight points and quadrantally in degrees.
Card-Consists of the white metal inside bowl. Graduated to eight points and quadrantally in degrees.
Needle-Bar type with spigot at North end. Jewelled pivot cap at centre. Length 3.4" (8.7cm)
Rests on circular wood and brass platform which is graduated to eight points and quadrantally in degrees. Platform moves in azimuth by thumb screw rack and pinion. Has vernier.
About this period, and later, there were quite a number of instruments of this description produced. Some of these were fitted with, or were attached to, compasses. It has been included as an illustration of what may be termed ?Navigation made easy? instruments. As might have been expected, none of these had a long life but were soon relegated to obscurity. Most of them appear to have been variations of Graydon?s patent No. 4996 of 1824.
caption: Record Shot - Do not reproduce. | Publisher: | "http://collections.rmg.co.uk/" | Rights holder: | "Royal Museums Greenwich" | Subjects: | celestial compasses | Source: | Royal Museums Greenwich | Identifier: | http://collections.rmg.co.uk/collections... | Go to resource |
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