Alexander Ross Clarke

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Not to be confused with Alex Clark or Alex Clarke.
Alexander Ross Clarke
Alexander Ross Clarke.jpg
Alexander Ross Clarke in 1861.
Born 16 December 1828
Reading, Berkshire, England
Died 11 February 1914
Strathmore, Reigate, Surrey
Nationality United Kingdom
Fields geodesy
Known for reference ellipsoids
Notable awards Royal Medal (1887)

Alexander Ross Clarke (16 December 1828 – 11 February 1914) was a British geodesist, primarily remembered for his work defining different reference ellipsoids approximating the shape of the geoid and determining the Figure of the Earth.

Clarke was born in Reading, Berkshire, England. He spent his childhood in the British colony of Jamaica, until his family returned to England.

Early career[edit]

On 1 October 1847, he joined the British army and was assigned to the Royal Engineers. He was trained at Chatham in Kent, at the School of Military Engineering. In 1850 he was transferred to the Ordnance Survey in Southampton.

From 1851 to 1854 Clarke served in Canada, where he married Frances Dixon in 1853.[citation needed] The couple had four sons and nine daughters.

Return to England[edit]

On his return to England he served again with the Ordnance Survey in Southampton, where in 1856 he became director of the measurement department. Between 1861 and 1881, he lived at No. 21 Carlton Crescent, Southampton.[1][2]

In 1858 he published his first article on the history of land surveying in Great Britain. On 5 June 1862, he was elected to the Royal Society. In 1866 he described a new reference ellipsoid, known as Clarke 1866 and still used today, particularly in English-language countries and areas.

In 1878, Clarke was appointed as temporary Director-General of the Ordnance Survey.[3]

His 1880 book, Geodesy, was the first major survey of the subject since the work of Airy. It covers the history of previous British and French geodetic surveys, techniques of survey methods and the theory of the Figure of the Earth. He concludes with an assessment of all previous meridian arc determinations and by combining them with his own British survey he established accurate values for an ellipsoid referred to as Clarke 1880,: it is used mainly in Africa.[4])


After he had served 27 years in England, he was formally obliged to serve overseas. Upon receiving notice of transfer, Clarke submitted his resignation. Soon after, he withdrew from the Royal Society for financial reasons.

In October 1883 Clarke was the British delegate at the geodetic conference in Rome, and in 1884 he represented Britain at the International Geodetic Conference.


From the Royal Society he received the gold medal,[5] and was re-elected to membership and his dues were waived.[citation needed]

Alexander Ross Clarke died on 11 February 1914 in Strathmore, Reigate, Surrey.[citation needed]


  1. ^ Leonard, A. G. K. (Autumn 2010). "Carlton Crescent: Southampton’s most spectacular Regency development". Southampton Local History Forum Journal. Southampton City Council. p. 42. Retrieved 23 March 2012. 
  2. ^ "17-22 Carlton Crescent". The National Heritage List for England. English Heritage. 14 July 1953. Retrieved 24 March 2012. 
  3. ^ "Directors-General of the Ordnance Survey". Charles Close Society. Retrieved 19 December 2012. 
  4. ^ Clarke, Alexander Ross, 1880: Geodesy. Clarendon Press. Recently republished at Forgotten Books
  5. ^ "CLARKE, Alexander Ross". Who's Who, 59: pp. 339–340. 1907. 
  • Colonel Sir Charles Close, K.B.E., C.B., C.M.G., F.R.S. "The Life and Work of Colonel Clarke." The Royal Engineers Journal Vol. XXXIX, No. 4 (December 1925), pp. 658–665.

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