Frederick James Lewis, surveyor-general of Natal, was the son of Charles Lewis and his wife Isabella, born Annandale. He was educated at Maritzburg College, Pietermaritzburg, and showed a strong aptitude for mathematics. In March 1892 he entered the civil service of Natal Colony as a clerical probationer and in July 1896 was appointed as a third class clerk in the office of the Surveyor-General. He was promoted to draughtsman and computer in September 1898, to acting examiner of diagrams in January 1908, and, after the formation of the Union of South Africa in 1910, to professional assistant to the surveyor-general of Natal in April 1912. In 1915 he succeeded John L. Watson* as surveyor-general of Natal, a position he held until his retirement in September 1929.
Lewis spent much of his time correcting earlier survey errors and putting urban surveys on a sound footing. He also compiled a Map of the Colony of Natal and Zululand (1897). After his retirement he pursued his interest in municipal affairs, served on the city council of Pietermaritzburg from 1931 until his death, and as mayor from 1936 to 1939. He was married to Francis Maud Goodwin, with whom he had two sons and two daughters.