Edward W. Andrews was the eldest son of John E. Andrews of Dublin, Ireland. He was educated in Cape Town and in 1893 married Maria W. Van der Merwe. They eventually had five children.
Andrews was a friend of the surveyor J.J. Bosman* and from 1892 assisted the latter in the reduction, solution of equations and computations connected with the triangulation of British Bechuanaland (now part of the Northern Cape). Much of this work was done in their spare time. The results were examined in detail by Dr David Gill*, who wrote a highly complimentary letter to Bosman in March 1895 regarding the work. Andrews joined the civil service of the Cape Colony in September 1895 as a human computer in the Surveyor-General's department. The Bechuanaland triangulation was subsequently connected at both its eastern and western extremities to the existing chains of the Geodetic Survey of South Africa. Bosman, assisted by Andrews, reduced the observations and adjusted the triangles, completing the work in 1901. The incorporation of these three surveys into the Geodetic Survey of South Africa amply confirmed the high quality of the work.
From 1903 Andrews assisted Bosman with the reduction of observations connected with the secondary triangulation of the Cape Colony and its adjustment to the Geodetic Survey. By 1908 he was Chief Computer of the secondary triangulation department in Cape Town. After the formation of the Union of South Africa he was appointed First Grade Computer in the Geodetic Survey, under the direction of Bosman, in the Cape Town office of the Surveyor-General.