Francis Baily (nonfiction)

Francis Bailey.

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.

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.

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.

Nonfiction cross-reference

• Baily's beads (nonfiction)
• Henry Cavendish (nonfiction)
• Tycho Brahe (nonfiction)

External links:

• Francis Baily @ Wikipedia