[4][5] He and his younger brother, Richard (1823–1895) were educated at Wellington House Academy, Hampstead, and at M. Liborel's school in Guînes in the Pas de Calais.
[4] He returned to London to seek work, and, on the recommendation of Davies Gilbert and Lieutenant Stratford,[1] was employed at the Royal Greenwich Observatory as a computer.
George Airy, the astronomer royal, was soon impressed by him, and in 1840 Dunkin was promoted to a post in the new magnetic and meteorological department, becoming a permanent member of the observatory's staff in 1845.
[8] Dunkin's meticulous accuracy and dependability led to him being given charge of a number of investigations, including the adjustment and error quantification of instruments such as Greenwich's new lunar azimuth and transit circle, and the expedition to Norway in 1851 to observe the total eclipse.
[5] Airy also used Dunkin as a reliable "man on the spot" in various non-Greenwich activities, including pendulum experiments at Harton colliery, and the determinations of the longitudes of the Brussels and Paris observatories.