Description
Artificial or mercury roof horizon, rectangular black-lacquered cast iron trough with pouring hole and brass-framed roof-shaped cover with clear glass panels. Round iron bottle filled with mercury with stopper and iron funnel, in fitted wooden carrying box, signed and made by Sewill, maker to the Royal Navy, Liverpool. Only a few copies of Sewill are known. Even the Maritime Museum in Greenwich does not have a copy.
The artificial horizon was used to establish the elevation of the sun or a star when the horizon was not visible. The vertical angle between the celestial body and its reflection in the mercury was measured. This had to be halved to establish the angle of elevation above the horizon.
Date: around 1850
HWL case: 15x22x15 cm
Signed: Sewill, Maker to the Royal Navy, Liverpool
Origin: England
Condition: excellent, perfect, the strap, however, is broken and incomplete
Mercury is poisonous, please pay attention!
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Dealer information
Archipel
Welcome to the catalogue of Archipel International Maritime Gallery, specialist in nautical antiques and collectables.
Archipel International Maritime Galery in the Netherlands, sets itself to maritime objects, globes and sea charts of before 1900. The managing director worked as officer with the mercantile marine and the Royal Navy. As curator he was connected to one of the University Museums in the Netherlands. As seaman and curator he has a lot of knowledge of naval history. The entire Archipel collection can be found at the site Archipel-img.com.