Thomas Hornsby
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Thomas Hornsby (1733 in
Durham Durham most commonly refers to: *Durham, England, a cathedral city and the county town of County Durham *County Durham, an English county * Durham County, North Carolina, a county in North Carolina, United States *Durham, North Carolina, a city in N ...
– 11 April 1810 in
Oxford Oxford () is a city in England. It is the county town and only city of Oxfordshire. In 2020, its population was estimated at 151,584. It is north-west of London, south-east of Birmingham and north-east of Bristol. The city is home to the ...
) was a British
astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...
and
mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...
.


Life

Hornsby became a Fellow of
Corpus Christi College, Oxford Corpus Christi College (formally, Corpus Christi College in the University of Oxford; informally abbreviated as Corpus or CCC) is one of the constituent colleges of the University of Oxford in the United Kingdom. Founded in 1517, it is the 12th ...
in 1760. He occupied the Savilian Chair of Astronomy at
Oxford University Oxford () is a city in England. It is the county town and only city of Oxfordshire. In 2020, its population was estimated at 151,584. It is north-west of London, south-east of Birmingham and north-east of Bristol. The city is home to the ...
from 1763. In the same year, he became
Sedleian Professor of Natural Philosophy The Sedleian Professor of Natural Philosophy is the name of a chair at the Mathematical Institute of the University of Oxford. Overview The Sedleian Chair was founded by Sir William Sedley who, by his will dated 20 October 1618, left the sum o ...
. Hornsby was especially concerned with the observation of the
transit of Venus frameless, upright=0.5 A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and a superior planet, becoming visible against (and hence obscuring a small portion of) the solar disk. During a trans ...
. In 1761, he observed the transit of Venus from
Shirburn Castle Shirburn Castle is a Grade I listed, moated castle located at the village of Shirburn, near Watlington, Oxfordshire. Originally constructed in the fourteenth century, it was renovated and remodelled in the Georgian era by Thomas Parker, the fi ...
, in
Oxfordshire Oxfordshire is a ceremonial and non-metropolitan county in the north west of South East England. It is a mainly rural county, with its largest settlement being the city of Oxford. The county is a centre of research and development, primarily ...
, the
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of the
Earl of Macclesfield Earl of Macclesfield is a title that has been created twice. The first creation came in the Peerage of England in 1679 in favour of the soldier and politician Charles Gerard, 1st Baron Gerard. He had already been created Baron Gerard, of Bra ...
.
George Parker, 2nd Earl of Macclesfield George Parker, 2nd Earl of Macclesfield, PRS (c. 1695 or 1697 – 17 March 1764) was an English peer and astronomer. Styled Viscount Parker from 1721 to 1732, he was Member of Parliament (MP) for Wallingford from 1722 to 1727, but his ...
(ca. 1695–1764), celebrated as an
astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...
, had spent most of his time conducting astronomical observations at Shirburn Castle; here he had built an
observatory An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. His ...
and a chemical laboratory. Despite the international efforts made to observe the 1761 transit, poor weather conditions hampered observations. In 1766 Hornsby informed the Royal Society that preparations needed to begin for the 1769 transit, his publication in the ''Philosophical Transactions of the Royal Society'' focusing attention on the "cone of visibility" indicating some of the better places to observe the transit. Hornsby himself viewed the 1769 transit at the Tower of the Five Orders, where the
Bodleian Library The Bodleian Library () is the main research library of the University of Oxford, and is one of the oldest libraries in Europe. It derives its name from its founder, Sir Thomas Bodley. With over 13 million printed items, it is the second- ...
is situated. In the periodical ''
Philosophical Transactions ''Philosophical Transactions of the Royal Society'' is a scientific journal published by the Royal Society. In its earliest days, it was a private venture of the Royal Society's secretary. It was established in 1665, making it the first journa ...
'', Hornsby published a comparative analysis of 1761 transit (1763); a plan for suitable viewing stations for 1769, including possible locations in the
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(1765); a description of organising and reporting observing groups in Oxford (1769); and a comparative analysis of the 1769 transit (1771). Hornsby was instrumental in the establishment of the
Radcliffe Observatory Radcliffe Observatory was the astronomical observatory of the University of Oxford from 1773 until 1934, when the Radcliffe Trustees sold it and built a new observatory in Pretoria, South Africa. It is a Grade I listed building. Today, the ...
at Oxford in 1772, and was made Radcliffe Observer in the same year. In 1782, he was appointed
Sedleian Professor of Natural Philosophy The Sedleian Professor of Natural Philosophy is the name of a chair at the Mathematical Institute of the University of Oxford. Overview The Sedleian Chair was founded by Sir William Sedley who, by his will dated 20 October 1618, left the sum o ...
. In 1783, he became Radcliffe Librarian. He was elected a Foreign Honorary Member of the
American Academy of Arts and Sciences The American Academy of Arts and Sciences (abbreviation: AAA&S) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and ...
in 1788. Hornsby made tens of thousands of astronomical observations. These were not published, however, until 1932, and were donated to
Corpus Christi College, Oxford Corpus Christi College (formally, Corpus Christi College in the University of Oxford; informally abbreviated as Corpus or CCC) is one of the constituent colleges of the University of Oxford in the United Kingdom. Founded in 1517, it is the 12th ...
in 1935. They include a determination of the rate of change of the axial inclination of the Earth and the
proper motion Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...
of
Arcturus , - bgcolor="#FFFAFA" , Note (category: variability): , , H and K emission vary. Arcturus is the brightest star in the northern constellation of Boötes. With an apparent visual magnitude of −0.05, it is the third-brightest of the ...
, both close to the modern values, whose combination of visual magnitude and large proper motion led Hornsby to argue (incorrectly) that "We may, I think, fairly conclude that Arcturus is the nearest Star to our System visible in this Hemisphere". The crater Hornsby on the
Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
is named after him. N.B. His death announcement in the Kentish Gazette 24 April 1810 quotes his death as "Wednesday (11th Apr. 1810) at the Observatory Oxford, aged 76, the Rev. Thomas Hornsby D.D. & F.R.S. Savalian Professor of Astronomy, Professor of Natural Philosophy, & Librarian of the Radcliffe Library."
The O.D.N.B gives this information:
"Hornsby, Thomas (1733–1810), astronomer, the son of Thomas Hornsby (bap. 1704, d. 1771), an apothecary and later alderman, and his wife, Thomasine Forster, née Coulson (bap. 1705, d. 1775), was baptized in the parish of St Nicholas, Durham, on 27 August 1733. Hornsby died in Oxford on 11 April 1810, and was buried at St Giles' there on 19 April."


Sources


Thomas Harriot's manuscripts
*Stephen Johnston, "Blast from the Past: Measurement and morals in the early Transits of Venus," ''Museum of the History of Science, University of Oxford'', at http://www.physics.ox.ac.uk/phystat05/Talks/johnston.ppt (accessed July 2006) *Kentish Gazette 24 April 1810 *Oxford Dictionary of National Biography {{DEFAULTSORT:Hornsby, Thomas 1733 births 1810 deaths 18th-century British astronomers 18th-century British mathematicians 19th-century British mathematicians Fellows of Corpus Christi College, Oxford Fellows of the American Academy of Arts and Sciences Fellows of the Royal Society Savilian Professors of Astronomy Sedleian Professors of Natural Philosophy