(1737-1810), Astronomer

William Bayly (spelt Bayley in some sources) was born in 1737 at Bishops Cannings, near Devizes, Wiltshire. After spending his boyhood at the plough, he took advantage of the offer of an exciseman from a neighbouring village to teach him the elements of mathematics, and was also helped later by a Mr Kingston of Bath. He became an usher at a school at Stoke, near Bristol, and to another nearby.

On 14 November 1766 Bayly was appointed assistant to the astronomer royal Nevil Maskelyne at the Royal Observatory, Greenwich. With his skills in mathematics already well versed, acquired the skills of observational astronomy so well that Maskelyne recommended that he should be one of the Royal Society's observers of the forthcoming transit of Venus. On 13 April 1769 he and Jeremiah Dixon sailed together for Nordkapp in Norway in HMS Emerald, and Bayly successfully observed the transit on 3 June at Nordkapp. He returned to Greenwich, where the Revd Malachy Hitchins had temporarily taken his place since April, and remained there as Maskelyne's assistant until 25 March 1771.

Captain Cook arrived home after his first Pacific voyage on 13 July 1771, and plans were made for a second voyage of discovery in the southern hemisphere, with two vessels. On 14 December, on Maskelyne's recommendation, the board of longitude appointed William Wales and Bayly to go as astronomers in the Resolution (Captain Cook) and Adventure (Captain Furneaux), respectively, 'to make Nautical & Astronomical Observations, and to perform other Services tending to the Improvement of Geography & Navigation' (Journals, 2.724). The two sloops sailed together from Plymouth on 13 July 1772, Adventure sailed home independently via Cape Horn, and reached Spithead on 14 July 1774. Of Bayly's Arnold chronometers, one stopped at the Cape outward bound, the other performed reasonably well throughout.

After returning to England, Bayly began preparing for submission to the board of longitude the observations he had made on the voyage. (They were eventually published in 1777, edited by Wales.) Then, when Cook reached England in Resolution, a little over a year after Adventure, plans were made for a third voyage, to explore the north Pacific Ocean. The ships were to be Cook's Resolution once again and the smaller Discovery (Captain Charles Clerke). Bayly was appointed astronomer for the Discovery. He joined the ship on 6 June 1776 and sailed a month later. Bayly was commissioned by the board to prepare the observations of Cook, King, and himself for the press, and they were published in 1782.

Bayly was appointed headmaster of the Royal Naval Academy in Portsmouth Dockyard on 18 February 1785, and kept his post, despite disciplinary and other troubles, until the academy was transformed into the Royal Naval College in 1807, when he was pensioned. His final years were sad, as he lost in rapid succession his wife and seven children, all by consumption. He died at Portsea, Hampshire, on 21 December 1810.