Francis Baily (28 April 1774 – 30 August 1844) was an English
astronomer. He is most famous for his observations of 'Baily's beads'
during an eclipse of the Sun. Baily was also a major figure in the
early history of the Royal Astronomical Society, as one of the
founders and president four times.
2 Astronomical work
4 Further reading
5 External links
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
Augustus de Morgan in 1856, Baily
London Stock Exchange 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.
By 1820, Baily had already taken a leading part in the foundation of
the Royal Astronomical Society, 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 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, Ulugh Beg, Tycho Brahe,
Edmund Halley 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, 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.
Baily's beads 4 seconds before totality
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'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 (1835) is of fundamental importance to the scientific
history of that time. It included a republication of the British
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 his home town of
Francis Baily CofE
^ Hockey, Thomas (2009). The Biographical Encyclopedia of Astronomers.
Springer Publishing. ISBN 978-0-387-31022-0. Retrieved 22 August
^ a b c d e f One or more of the preceding
sentences incorporates text from a publication now in the public
domain: Chisholm, Hugh, ed. (1911). "Baily, Francis".
Encyclopædia Britannica. 3 (11th ed.). Cambridge University Press.
p. 221. 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
Month. Not. R. Astr. Soc. xiv. 1844.
^ a b Dreyer, John L. E.; Turner, Herbert H. (1923). History of the
Royal Astronomical Society, 1820–1920. 1. London: Royal Astronomical
^ a b "Gold Medal Winners" (PDF). RAS. 2014. Retrieved 9 January
2015. [permanent dead link]
^ a b "List of Presidents and Dates of Office". A brief history of the
RAS. Royal Astronomical Society. Retrieved 10 September 2012.
^ "Book of Members, 1780–2010: Chapter B" (PDF). American Academy of
Arts and Sciences. Retrieved 5 May 2011.
Herschel, John (1844). "Memoir of the late Francis Baily". Monthly
Notices of the Royal Astronomical Society. 6: 89–121.
Dieke, Sally H. (1970). "Baily, Francis". Dictionary of Scientific
Biography. 1. New York: Charles Scribner's Sons. pp. 402–403.
Higgitt, Rebekah (Mar 2004). "Astronomers against Newton". Endeavour
(published March 2004). 28 (1): 20–4.
doi:10.1016/j.endeavour.2004.01.012. PMID 15036924.
Works written by or about
Francis Baily at Wikisource
"Baily, Francis". Dictionary of National Biography.
Map of Etoiles fixes
Awarding of RAS gold medal, 1827: MNRAS 1 (1827) 14
Awarding of RAS gold medal, 1843: MNRAS 5 (1843) 248
"Archival material relating to Francis Baily". UK National
ISNI: 0000 0001 1470 7873
BNF: cb13498001d (data)