 In the early 1830s he was in private practice in Van Diemen's Land as a surveyor, then moved to New South Wales where he joined the survey department.In 1836 he was sent as an Assistant Surveyor under Robert Russell to survey the new settlement at Port Phillip.At Port Phillip Darke carried out some of the first surveys of the new town of Melbourne and was instrumental in laying out the streets of the new town for sale at the first land auctions.