Robert Brown, FRS, lived from 21 December 1773 to 10 June 1858. He was a botanist best known for his work in Australia, and he was also the one of the first to observe the phenomenon since called Brownian motion. The wider picture in Scotland at the time is set out in our Historical Timeline.
Robert Brown was born in Montrose. After being schooled locally he went on to become a medical student at the University of Edinburgh, where fellow students included Thomas Dick and Robert Jameson. In 1795 he joined the army as a surgeon, and in 1800 volunteered to serve as the naturalist on board HMS Investigator during the circumnavigation of Australia by Captain Matthew Flinders, RN. The expedition arrived off what is now Western Australia in December 1801. Over the next two and a half years Brown collected some 3400 species of plants, of which around 2000 were previously unknown. Much of the collection was lost when the ship on which Brown was returning to England, HMS Porpoise was wrecked on the Great Barrier Reef in August 1803. He stayed in Australia until May 1805 reassembling his collection and then returned to Britain, where he spent five years studying the material and writing his Prodromus Florae Novae Hollandiae et Insulae Van Diemen, or "Prodromus of the Flora of New Holland and Van Diemen's Land".
In 1810 Brown was appointed librarian to the naturalist Sir Joseph Banks, and on Banks' death in 1820 Brown inherited his library and herbarium. He passed ownership to the British Museum in 1827, and was in return appointed Keeper of the Banksian Botanical Collection at the Museum.
In 1827, Brown was using a microscope to study pollen grains and spores suspended in water. During the process he observed minute particles within the pollen grains undergoing a continuous jittery motion. He later observed the same type of motion in particles of dust, thus ruling out a cause associated with the pollen being alive. Brown did not produce an explanation for the motion, and it later emerged he had not actually been the first to observe it, but it is nonetheless known to modern science as Brownian motion. In a paper published in 1833, Brown became the first person to name and describe in detail the cell nucleus, though at the time he though it was a structure specific to the type of cells he was studying. In 1837 he became Keeper of the Botanical Department at the British Museum.
Robert Brown died in London in 1858. A number of the plants he discovered in Australia were named after him, as was Brown's Tetrodontium Moss, which he discovered at Roslin near Edinburgh while a student. Brown's River, in Tasmania, is also named after him.