In 1834 he entered the service of the Survey department of New South Wales, spending a considerable period in the Illawarra district. Burnett was selected by Sir
Thomas Mitchell to lead a survey to trace the Great Dividing Range from south of Hanging Rock northward towards
Moreton Bay. Burnett set off in October 1841 with Roderick Mitchell (son of Thomas Mitchell) as second-in-command of the party. After many difficulties, the range was traced to about the 30°S and then the party headed for Brisbane arriving September 1842. Burnett subsequently undertook surveys of the
Clarence River and
Richmond River. In 1846, he was appointed in charge of the surveys in Moreton Bay and settled in Brisbane. In 1846 to 1847 he explored north of Moreton Bay in the area of the
Mary River and
Burnett River. His efforts in exploring Queensland (as it is now known) were recognised by
New South Wales Governor Charles Augustus FitzRoy by naming the
Burnett River and the surrounding area after Burnett. ==Later life==