William Lax FRS (1761 – 29 October 1836) was an English astronomer and mathematician who served as Lowndean Professor of Astronomy and Geometry at the University of Cambridge for 41 years.

He attended Trinity College, Cambridge and graduated Bachelor of Arts as the Senior Wrangler and first Smith's Prizeman of his year.

Lax was best known for his Remarks on a Supposed Error in the Elements of Euclid (1807) and his work regarding the Nautical Almanac, which was an important reference for navigation in the period.

He was educated at the Kirby Ravensworth Free Grammar School, where he learned Latin (in which he became fluent) and Greek as well as English language, arithmetic and mathematics.

[3] Sizars were students who were not of the gentlemanly class, who were charged lower fees and obtained free food and/or lodging and other assistance during their period of study in exchange for performing work at their colleges.

As a moderator Lax was responsible for the introduction of "very high flown compliments, and at the same time extending the disputations to double the usual length, which was around one hour and ten minutes" which "sent a ripple through tradition" according to Greg Dening.

During Lax's tenure a mathematical chair was seen as "a prize or a means of securing leisure, and at best, merely as offering a position where a man could pursue his own researches undisturbed by other duties".

[19] The sole duty of Lax's professorship was that he was required to examine students annually for the Smith's Prize, including John Herschel, Adam Sedgwick, George Biddell Airy and William Cavendish, 7th Duke of Devonshire.

[23] Newtonian mathematics teaching as exemplified by "Cambridge traditionalists" such as Lax and his generation began to wane as the Georgian era drew to a close.

[24] In 1817 George Peacock successfully introduced the new French mathematics (such as Pierre-Simon Laplace and Joseph Louis Lagrange) into the Senate House Examinations.

"[25] For the traditionalists the struggle was more than one of intellectual difference as for them, "Newton's rational mechanics, fluxions, and experimental philosophy were an excellent antidote against materialism and atheism.

[16] By the 1820s it was no longer acceptable to consider chairs as sinecures, and Lax received criticism from a living descendant of the original benefactor, Thomas Lowndes, for being remiss in his duties.

[32] However, due to an enmity of the President Joseph Banks, friends of Charles Hutton and Maskelyne, such as Lax, Samuel Vince and Thomas Mudge, frequently saw their submissions for publications overlooked.

[39][40] However the method described by Lax "though very ingenious, requires great labour and time, and is inferior in accuracy and efficiency to that which was adopted by Mr. Troughton for tabulating the errors of the primary divisions of circular instruments.

[44][45] The Board was a governmental body charged with administering a scheme of prizes intended to encourage innovators to solve the problem of finding longitude at sea, which was vital for accurate navigation.

[48] However, the extraordinarily accurate chronometers of John Harrison were generally available from the 1820s onwards, rendering the lunar distance method, which Lax had used to create the tables, immaterial.

[49] As a scientific member of the Board, Lax was one of eighteen men who were, according to Edmund Dews, "ultimately responsible for the form and contents of the Nautical Almanac.

[50] In 1828 Lax appended An easy method of correcting the lunar distance, on account of the spheroidal figure of the earth to the Nautical Almanac.

[52] On 28 February 1801 Lax was granted the livings as vicar of Marsworth, Buckinghamshire and squarson of Great Wymondley with St Ippolyts near Hitchin, Hertfordshire "after some years of teaching work".

[58] That same year he created a park opposite to the vicarage similar to The Backs of Cambridge, built a replica of Trinity College Bridge, dammed the stream and opened springs to form a lake which was used for ice skating in the winter.

[70] His obituary in The Gentleman's Magazine reported that "his constitution was broken in early life [which] made his last years a period of weakness and suffering, so that his physical strength was unequal to the workings of his active mind.