Francis Baily | |
|---|---|
.jpg) Royal Astronomical Society portrait | |
| Born | (1774-04-28)28 April 1774 Newbury, Berkshire, England |
| Died | 30 August 1844(1844-08-30) (aged 70) London, England |
| Resting place | St Mary's Church inThatcham |
| Known for | Baily's beads President of the Royal Astronomical Society |
| Awards | Gold Medal of the Royal Astronomical Society (1827 & 1843) |
| Scientific career | |
| Fields | Astronomy |
Francis Baily (28 April 1774 – 30 August 1844) was an Englishastronomer. He is most famous for his observations of "Baily's beads" during a totaleclipse of the Sun. Baily was also a major figure in the early history of theRoyal Astronomical Society, as one of the founders and as the president four times.
Baily was born atNewbury in Berkshire in 1774 to Richard Baily.[1] After a tour in the unsettled parts of North America in 1796–1797, his journal of which was edited byAugustus De Morgan in 1856, Baily entered theLondon Stock Exchange in 1799. The successive publication ofTables for the Purchasing and Renewing of Leases (1802), ofThe Doctrine of Interest and Annuities (1808), andThe 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.[2]
By 1820, Baily had already taken a leading part in the foundation of theRoyal Astronomical Society,[3] and he received itsGold Medal in 1827[4] for his preparation of the Society'sCatalogue of 2881 stars (Memoirs R. Astr. Soc. ii.).[2] Later, in 1843, he would win the Gold Medal again.[4] He was elected asPresident of the Royal Astronomical Society four times, with two-year terms each (1825–1827, 1833–1835, 1837–1839 and 1843–1845).[3][5] No other person has served in the position more than Baily's four times (a record he shares withGeorge Airy), whilst his eight years in the post are a record.
The reform of theNautical Almanac in 1829 was set on foot by his protests[discuss]. He was elected a Foreign Honorary Member of theAmerican Academy of Arts and Sciences in 1832.[6] He recommended to theBritish Association in 1837, and in great part executed, the reduction ofJoseph de Lalande's andNicolas de Lacaille's catalogues containing about 57,000[citation needed] stars; he superintended the compilation of the British Association'sCatalogue of 8377 stars (BAC, published 1845);[7] and revised the catalogues ofTobias Mayer,Ptolemy,Ulugh Beg,Tycho Brahe,Edmund Halley andHevelius (Memoirs R. Astr. Soc. iv, xiii.).[2]
His observations of "Baily's Beads", during an annular eclipse of the Sun on 15 May 1836, at Inch Bonney inRoxburghshire, 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 atPavia.[2]
In other work, he completed and discussedH. 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 byHenry Cavendish's method (1838–1842), yielded the authoritative value of 5.66.[2]
Baily died in London on 30 August 1844 and was buried in the family vault inSt Mary's Church inThatcham,Berkshire. 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 Catalogue.[2]
Thelunar craterBaily 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).[citation needed]
One or more of the preceding sentences incorporates text from a publication now in thepublic domain: Chisholm, Hugh, ed. (1911). "Baily, Francis".Encyclopædia Britannica. Vol. 3 (11th ed.). Cambridge University Press. p. 221. This also cites Works by or aboutFrancis Baily atWikisource