A late Victorian mercury type collapsible artificial horizon by Cary of London.
Used with a sextant, on a stand, to measure the hight of a celestrial body, when the horizon can not be used, like on land.
This top quality instrument is comprised of a mahogany hinged case with original lock and additional hook and eye fixings to the front. Contained within the box is a black painted metal trough and triangular lid with a two paned glass top to enable viewing and to protect the mercury from the elements when in use. The case engraved to, “Cary, London” is hinged in such a way that it can be collapsed flat for convenient storage. The box also contains its original painted metal mercury flask with ingenious reversible lid to allow for the decanting of the mercury back from the trough into safe keeping after use. Please note, there is no mercury present with this piece, but the unscrewing-device is included.
In addition to the engraving on the instrument, there is a second label on the box for the reseller, Henry Hughes & Son Ltd, Opticians, 59 Fenchurch St, London.