During this period he contributed regularly to the Mining Journal, edited by George Stevenson, at that time considered the best-conducted paper in South Australia.
[2] When the Victorian gold fields were discovered in 1851 Sinnett left South Australia for Melbourne, and accepted an engagement as contributor to the Herald, of which paper he became eventually editor and part proprietor.
About 1855 he severed his connection with that paper and became a contributor to the Melbourne Argus, with which journal he remained till 1859, with the exception of a short period spent in editing the Daily News at Geelong.
[2] About the time that he joined the Argus was commenced the Melbourne Punch, of which journal he was one of the founders, and to the success of which he greatly contributed.
During his sojourn in South Australia from 1859 to 1865 he founded and edited the evening Telegraph,[3] and was Parliamentary reporter for Hansard.