Jonathan Sisson was an English instrument maker, the inventor of the modern theodolite with a sighting telescope for surveying, and a leading maker of astronomical instruments.
24 Facts About Jonathan Sisson
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Jonathan Sisson was apprenticed to George Graham, then became independent in 1722.
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Jonathan Sisson remained an associate of Graham and of the instrument maker John Bird.
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Jonathan Sisson became a well-known maker of optical and mathematical instruments.
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In 1729 Jonathan Sisson was appointed mathematical instrument maker to Frederick, Prince of Wales.
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Jonathan Sisson's apprentice John Dabney, junior, was an early instrument maker in the American colonies, who arrived in Boston in 1739.
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Jonathan Sisson employed John Bird, his co-worker under Graham, who became another leading supplier of instruments to the Royal Observatory.
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Jonathan Sisson made portable sundials with a compass in the base for use in aligning the instrument with the Earth's axis.
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However, Jonathan Sisson became renowned for his instruments for surveying, navigation, the measurement of lengths and astronomy.
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Jonathan Sisson designed an early type of surveyor's level, the Y-level, where a telescope rests in Y-shaped bearings and is removable.
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Jonathan Sisson initially built theodolites with plain sights, then made the key innovation of introducing a telescopic sight.
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Jonathan Sisson's theodolites have some similarity to earlier instruments such as that built by Leonard Digges, but in many ways are the same as modern devices.
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The 30 inches radius quadrant built by Jonathan Sisson was found to be accurate within.
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In 1732 Jonathan Sisson was selected to make a brass octant to John Hadley's new design.
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Jonathan Sisson was well known for the exact division of his scales, for measuring lengths.
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In 1742 George Graham, who was a Fellow of the Royal Society, asked Jonathan Sisson to prepare two substantial brass rods, well-planed and squared and each about 42 inches long, on which Graham very carefully laid off the length of the standard English yard held in the Tower of London.
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Jonathan Sisson made large astronomical instruments that were used by several European observatories.
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Jonathan Sisson made rigid wall-mounted brass quadrants with radii of 6 to 8 feet.
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Graham employed Jonathan Sisson to make the Royal Observatory's 8 feet mural quadrant.
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One of Jonathan Sisson's instruments was loaned by Pierre Lemonnier to the Berlin Academy, where it was used to supplement observations at the Cape of Good Hope by Nicolas Louis de Lacaille of the lunar parallax.
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Pope Benedict XIV arranged for astronomical instruments purchased from Jonathan Sisson to be installed in the Specola observatory of the Academy of Sciences of Bologna Institute.
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Jonathan Sisson made his first equatorial instrument of this design for Archibald, Lord Ilay, and it was now held by the college at Aberdeen.
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Jonathan Sisson's equatorial mounting design had first been proposed in 1741 by Henry Hindley of York.
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Jonathan Sisson's transit telescope used a hollow-cone design for its axis, a design adopted by later instrument makers such as Jesse Ramsden.