Writing in the "South Australian Register", George William Francis, director of the Botanic Garden, said that the 32 species of timber Ninnis had collected settled "that important question, is there timber around proposed capital or not?" Noting that the member of the expedition originally intended to return biological specimens to Adelaide had failed to do so, Francis wrote that "we are very much indebted to this gentleman who has thus supplied us at a time when we have failed in obtaining information through the appointed channel." Upon the conclusion of the expedition in 1866, Ninnis received the thanks of the Parliament of South Australia for his work. His research on the expedition later formed the basis of a published work, "Remarks on the Natural History, Meteorology, and Native Population of Northern Australia".