Francis Baily (28 April 177430 August 1844) was an English
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, moons, comets and galaxies – in either o ...
. He is most famous for his observations of "
Baily's beads" during a total
eclipse
An eclipse is an astronomical event that occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three ce ...
of the Sun. Baily was also a major figure in the early history of the
Royal Astronomical Society
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, as one of the founders and as the president four times.
Life
Baily was born at
Newbury in Berkshire in 1774 to Richard Baily. After a tour in the unsettled parts of North America in 1796–1797, his journal of which was edited by
Augustus de Morgan in 1856, Baily entered the
London Stock Exchange
London Stock Exchange (LSE) is a stock exchange in the City of London, England, United Kingdom. , the total market value of all companies trading on LSE was £3.9 trillion. Its current premises are situated in Paternoster Square close to St Pa ...
in 1799. The successive publication of ''Tables for the Purchasing and Renewing of Leases'' (1802), of ''The Doctrine of Interest and Annuities'' (1808), and ''The Doctrine of Life-Annuities and Assurances'' (1810), earned him a high reputation as a writer on life-contingencies; he amassed a fortune through diligence and integrity and retired from business in 1825, to devote himself wholly to astronomy.
[ This also cites
* J. Herschel's ''Memoir of F. Baily, Esq.'' (1845), also prefixed to Baily's ''Journal of a Tour'', with a list of his writings (see ''Further reading'').
* ''Month. Not. R. Astr. Soc.'' xiv. 1844.]
Astronomical work
By 1820, Baily had already taken a leading part in the foundation of the
Royal Astronomical Society
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,
[ and he received its Gold Medal in 1827] for his preparation of the Society's ''Catalogue of 2881 stars'' (''Memoirs R. Astr. Soc.'' ii.). Later, in 1843, he would win the Gold Medal again.[ He was elected as President of the Royal Astronomical Society four times, with two-year terms each (1825–27, 1833–35, 1837–39 and 1843–45).] No other person has served in the position more than Baily's four times (a record he shares with George Airy), whilst his eight years in the post are a record.
The reform of the Nautical Almanac in 1829 was set on foot by his protests. 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, ...
in 1832. He recommended to the British Association in 1837, and in great part executed, the reduction of Joseph de Lalande's and Nicolas de Lacaille's catalogues containing about 57,000 stars; he superintended the compilation of the British Association's ''Catalogue of 8377 stars'' (published 1845); and revised the catalogues of Tobias Mayer, Ptolemy
Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of import ...
, Ulugh Beg
Mīrzā Muhammad Tāraghay bin Shāhrukh ( chg, میرزا محمد طارق بن شاہ رخ, fa, میرزا محمد تراغای بن شاہ رخ), better known as Ulugh Beg () (22 March 1394 – 27 October 1449), was a Timurid sultan, as ...
, Tycho Brahe
Tycho Brahe ( ; born Tyge Ottesen Brahe; generally called Tycho (14 December 154624 October 1601) was a Danish astronomer, known for his comprehensive astronomical observations, generally considered to be the most accurate of his time. He was ...
, Edmund Halley
Edmond (or Edmund) Halley (; – ) was an English astronomer, mathematician and physicist. He was the second Astronomer Royal in Britain, succeeding John Flamsteed in 1720.
From an observatory he constructed on Saint Helena in 1676–77, ...
and Hevelius (''Memoirs R. Astr. Soc.'' iv, xiii.).
His observations of " Baily's Beads", during an annular eclipse of the sun on 15 May 1836, at Inch Bonney in Roxburghshire
Roxburghshire or the County of Roxburgh ( gd, Siorrachd Rosbroig) is a historic county and registration county in the Southern Uplands of Scotland. It borders Dumfriesshire to the west, Selkirkshire and Midlothian to the north-west, and ...
, started the modern series of eclipse expeditions. The phenomenon, which depends upon the irregular shape of the moon's limb, was so vividly described by him as to attract an unprecedented amount of attention to the total eclipse of 8 July 1842, observed by Baily himself at Pavia
Pavia (, , , ; la, Ticinum; Medieval Latin: ) is a town and comune of south-western Lombardy in northern Italy, south of Milan on the lower Ticino river near its confluence with the Po. It has a population of c. 73,086. The city was the cap ...
.
In other work, he completed and discussed H. Foster's pendulum experiments, deducing from them an ellipticity for the Earth of 1/289.48 (Memoirs R. Astr. Soc. vii.). This value was corrected for the length of the seconds-pendulum by introducing a neglected element of reduction, and was used, in 1843, in the reconstruction of the standards of length. His laborious operations for determining the mean density of the Earth, carried out by Henry Cavendish
Henry Cavendish ( ; 10 October 1731 – 24 February 1810) was an English natural philosopher and scientist who was an important experimental and theoretical chemist and physicist. He is noted for his discovery of hydrogen, which he termed "infl ...
's method (1838–1842), yielded the authoritative value of 5.66.
Baily died in London on 30 August 1844 and was buried in the family vault in St Mary's Church in Thatcham. His Account of the Rev. John Flamsteed
John Flamsteed (19 August 1646 – 31 December 1719) was an English astronomer and the first Astronomer Royal. His main achievements were the preparation of a 3,000-star catalogue, ''Catalogus Britannicus'', and a star atlas called '' Atlas C ...
(1835) is of fundamental importance to the scientific history of that time. It included a republication of the British Catalogue.
The lunar crater Baily was named in his honour, as was the rigid and thermally insensitive alloy used to cast the 1855 standard yard (''Baily's metal'', 16 parts copper, 2.5 parts tin, 1 part zinc) and a local primary school in the town of Thatcham (Francis Baily CofE Primary School).
References
Further reading
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External links
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Map of Etoiles fixes
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{{DEFAULTSORT:Baily, Francis
1774 births
1844 deaths
Burials in Berkshire
People from Newbury, Berkshire
People from Thatcham
19th-century British astronomers
Fellows of the American Academy of Arts and Sciences
Fellows of the Royal Society
Fellows of the Linnean Society of London
Recipients of the Gold Medal of the Royal Astronomical Society
Presidents of the Royal Astronomical Society