Lucas did not confine his life to school work, and while at Wesley College also lectured on natural science to the colleges at the
University of Melbourne, and in later years lectured on physiography at the
University of Sydney. He also took much interest in the various learned societies, and during his early days at Melbourne was president of the
Field Naturalists Club of Victoria (which was founded by his brother) and edited the
Victorian Naturalist for some years. Lucas was a member of the council of the
Royal Society of Victoria, and subsequently of the
Linnean Society of New South Wales, of which he also became president (1907–1909). Lucas contributed many papers to their proceedings; a list of more than 60 will be found in the
Proceedings of the Linnean Society of New South Wales, vol. LXII, pp. 250–2. He described several new species of Australian reptiles (1894–1903) with Charles Frost. He wrote with
Arthur Dendy An Introduction to the Study of Botany which was published in 1892 (3rd ed. 1915), with W. H. D. Le Souef,
The Animals of Australia (1909), and
The Birds of Australia (1911). After retiring from school teaching at 70 years of age, Lucas became acting-professor of mathematics at the
university of Tasmania for over two years. He afterwards continued his scientific studies, giving particular attention to the algae on which he was the Australian authority. His handbook, Part 1 of
The Seaweeds of South Australia was issued just after his death. His large collection of algal specimens was bequeathed to the Commonwealth of Australia. It was initially stored at the
CSIRO offices in Canberra and then moved for easier access by researchers to the
National Herbarium of New South Wales. This move, and curation of the collection, was overseen by
Valerie May. ==Family life==