In 1798, Brown heard that Mungo Park had withdrawn from a proposed expedition into the interior of New Holland (now Australia), leaving a vacancy for a naturalist. At Brown's request, Correia wrote to Sir Joseph Banks, suggesting Brown as a suitable replacement:
"Science is the gainer in this change of man; Mr Brown being a professed naturalist. He is a Scotchman, fit to pursue an object with constance and cold mind."
He was not selected, and the expedition did not end up going ahead as originally proposed, though George Caley was sent to New South Wales as a botanical collector for Banks. In 1800, however, Matthew Flinders put to Banks a proposal for an expedition that would answer the question whether New Holland was one island or several. Banks approved Flinders' proposal, and in December 1800 wrote to Brown offering him the position of naturalist to the expedition. Brown accepted immediately.
Preparations
Brown was told to expect to sail at the end of 1800, only a few weeks after being offered the position. However a succession of delays meant the voyage did not get under way until July 1801. Brown spent much of the meantime preparing for the voyage by studying Banks' Australian plant specimens and copying out notes and descriptions for use on the voyage.
Though Brown's brief was collect scientific specimens of all sorts, he was told to give priority to plants, insects and birds, and to treat other fields, such as geology, as secondary pursuits. In addition to Brown, the scientific staff comprised the renowned botanical illustrator Ferdinand Bauer; the gardener Peter Good, whose task was to collect live plants and viable seed for the use of Kew Gardens; the miner John Allen, appointed as mineralogist; the landscape artist William Westall; and the astronomer John Crosley, who would fall ill on the voyage out and leave the ship at the Cape of Good Hope. Brown was given authority over Bauer and Good, both of whom were instructed to give any specimens that might collect to Brown, rather than forming separate collections. Both men would provide enthusiastic and hard-working companions for Brown, and thus Brown's specimen collections contain material collected by all three men.
Desertas, Madeira and the Cape of Good Hope
The
Investigator sailed from London on 18 July. They made brief landfalls at Bugio Island (Desertas Islands) and Madeira, but Brown was disappointed to collect almost nothing of note from either site. They arrived at the Cape of Good Hope on 16 October, staying a little over two weeks, during which time Brown made extensive botanical expeditions, and climbed Table Mountain at least twice. Many years later he would write to William Henry Harvey, who was considering emigrating there, that "some of the pleasantest botanizing he ever had was on Devil's Mountain, near Cape Town, and he thought I could not pitch on a more delightful field of study." Amongst the plants collected at the Cape were two new species of
Serruria (Proteaceae),
S. foeniculacea and
S. flagellaris.
Australia
The
Investigator arrived in King George Sound in what is now Western Australia in December 1801. For three and a half years Brown did intensive botanic research in Australia, collecting about 3400 species, of which about 2000 were previously unknown. A large part of this collection was lost, however, when the
Porpoise was wrecked
en route to England.
Brown remained in Australia until May 1805. He then returned to Britain where he spent the next five years working on the material he had gathered. He published numerous species descriptions; in Western Australia alone he is the author of nearly 1200 species.