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Artificial mercury horizon.

Artificial mercury horizon.

1860-1869

Artificial mercury horizon.

Artificial mercury horizon.

1855-1865

Artificial mercury horizon in case.

Artificial mercury horizon in case.

1860-1870

Artificial mercury horizon with case.

Artificial mercury horizon with case.

1895-1900

Artificial mercury horizon.

Artificial mercury horizon.

1835-1845

Artificial mercury horizon.

Artificial mercury horizon.

1845-1855

Brass lacquered sextant with straight-bar-pattern, 24 pillar frame, polished brass limb, wooden handle with counterbalanced tripod pillar stand and mercury artificial horizon in wooden box, all by John and Edward Troughton, 136 Fleet Street , London, England, 1790-1800. Consists of brass 127° scale (-5° to 140°) with 20’ divisions and brass vernier (10”), three index-filter shades (red & green), two horizon filters (red & green), scale magnifier on 90mm swivelling arm. Fitted with threaded telescope bracket for sighting telescope (182mm – inverted image) with 2 extra draw tubes, 131mm sighting tube and other accessories. The fitted rectangular case has in the lid the trade card for J. & E. Troughton. The artificial mercurial horizon consisting of a rectangular wooden trough fitted in a tin tray and a brass-framed, roof-shaped cover with glazed side panels, unsigned, made later, 1845-55.

Brass framed sextant with stand, artificial horizon and case.

1790-1800

Artificial mercury horizon with fitted leather carrying case, designed by Captain Christopher, provisionally patented in 1868 (No.2624), by the company of William Cary, 1868-1875. Consists of two black-lacquered steel mercury holders on three levelling feet, interconnected by a tube fitted with a stopcock. One is a storage reservoir with a valve to admit air and empty the mercury into the other, which is used for making observations and is fitted with a glass cover. A spare glass cover in a chamois leather pouch, and a lever pin for operating the stopcock (both stored in the glass-covered reservoir).

Artificial mercury horizon.

1865-1875

Artificial mercury horizon with mercury container and storage case with trade card, made by Thomas Jones, 62 Charing Cross, London, 1835-1845. Consists of a rectangular metal trough, with wooden lining, and loose fitting roof-shaped brass cover with side glazed panels. The mercury bottle is a flat wooden container with wood screw stopper. Marked, ‘F.26.’ the property mark of the Hydrographic Office of the British Admiralty (adopted February 1828).

Artificial mercury horizon.

1835-1845

Artificial mercury horizon, designed by Captain Christopher, provisionally patented in 1868 (No.2624), by the company of William Cary, 1868-1875. Consists of two black-lacquered steel mercury holders on three levelling feet, interconnected by a tube fitted with a stopcock. One is a storage reservoir with a valve to admit air and empty the mercury into the other, which is used for making observations and is fitted with a glass cover.

Artificial mercury horizon.

1865-1875

Artificial mercury horizon with mercury container, made by Thomas Jones, 62 Charing Cross, London, 1835-1845. Consists of a rectangular metal trough, with wooden lining, and loose fitting roof-shaped brass cover with side glazed panels. The mercury bottle is a flat wooden container with wood screw stopper. Marked, ‘F.26.’ the property mark of the Hydrographic Office of the British Admiralty (adopted February 1828).

Artificial mercury horizon.

circa 1840

Artifical horizon and cover with boxwood mercury bottle for 18-inch reflecting circle

Artificial mercury horizon for reflecting circle.

1790-1826