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Artificial Horizon - Troughton & Simms, London, circa 1850s Object Reg. No: ST 022154

Summary:
Artificial horizon, made by Troughton & Simms, London. Used at both Williamstown Observatory and Melbourne Observatory, and for Geodetic Survey of Victoria.

The artificial horizon was used, especially in field observations, to establish the elevation of the sun or a star when the horizon was not visible. The vertical angle between the sun or star and its reflection in the mercury was measured; this was halved to establish the angle of elevation above the horizon.
Description:
Rectangular metal trough covered by metal roof with two inclined panes of clear glass to prevent wind from agitating the surface of the mercury. Mercury contained in metal container with conical lid. In cedar case.
Acquisition Information:
Transfer from Melbourne Observatory, 1945
Discipline: Technology
Dimensions: 13 cm (Height), 15 cm (Width), 19 cm (Length)

More information

Tagged with: geodetic surveys, surveying apparatus instruments, artificial horizons, sextants
Themes this item is part of: Troughton & Simms, Instrument Makers, Melbourne Observatory Collection, Engineering Collection, Science & Measurement Collection, Transport Collection, Positional Astronomy at Melbourne Observatory, Weights & Measures at Melbourne Observatory, Melbourne Observatory & Standard Time in Victoria, Melbourne Observatory & Standard Time in Victoria, Astrographic Catalogue, Transits of Venus, 1874 & 1882, Buildings at Melbourne Observatory, Star Observations & Personal Equation, Meteorology at Melbourne Observatory, 1863-1908, Williamstown Observatory, 1853-1863, Melbourne Observatory, 1863-1944, Geodetic Survey of Victoria, 1858-1872, Geodetic Survey of Victoria, 1858-1872
Primary Classification: SURVEYING & NAVIGATION
Secondary Classification: Optical
Tertiary Classification: artifical horizons
Inscriptions: Cover inscribed "S.G.O. no 108. Troughton & Simms, London.". SGO = Surveyor General's Office.
Maker: Troughton & Simms, London, Middlesex, England, Great Britain, pre 1863
User: Williamstown Observatory, Williamstown, Victoria, Australia
User: Melbourne Observatory, South Yarra, Victoria, Australia

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