Robert Brown(1773–1858)

Robert Brown was born at Montrose in Angus on the twenty-first of December 1773, the son of an Episcopalian minister of a non-juring congregation. He went to the grammar school of Montrose alongside the boy who would become Joseph Hume the radical, then to Marischal College in Aberdeen at fourteen, and on to the University of Edinburgh in 1790 to read medicine. He took no degree but came out of Edinburgh a competent botanist; by his early twenties he was reading papers on Scottish ferns to the Edinburgh Natural History Society. He joined the Royal Fife Fencibles in 1795 as an ensign and surgeon's mate, was posted to Ireland through the rising of 1798, and used the long quiet hours of garrison duty in Mayo, Antrim and Donegal to keep working at his botany.

In 1798 in London he met Sir Joseph Banks, the patriarch of British natural history and the founder of Kew, who in 1800 recommended him to the Admiralty as naturalist to the voyage of HMS Investigator, the ship that under Captain Matthew Flinders was being fitted out to chart the coasts of New Holland, then a country still largely unknown to European science. The Investigator sailed from Spithead in July 1801, reached Cape Leeuwin in December, and over the next two and a half years carried Brown and the botanical artist Ferdinand Bauer round the south, east and northern coasts of the continent. Brown collected close to four thousand plant species, the great majority of them new to science, in the longest single botanical reconnaissance of a continent ever undertaken.

He returned to England in October 1805 with the Investigator collections, and over the next five years prepared the Prodromus Florae Novae Hollandiae et Insulae Van-Diemen, published in 1810, which described the floras of Australia and Tasmania on the new natural system of Antoine-Laurent de Jussieu in place of the older artificial system of Linnaeus. It is the founding text of Australian botany and one of the founding texts of systematic plant taxonomy in the English-speaking world. He was appointed Librarian to the Linnean Society of London in 1806 and Sir Joseph Banks's personal librarian in 1810; on Banks's death in 1820 Banks bequeathed him the use for life of his great library and herbarium at Soho Square, and Brown in turn bequeathed them to the British Museum.

From 1827 to 1858 he was the first Keeper of Botany at the British Museum, with charge of the national collections that the Banksian bequest had made the foremost in the world. The great discoveries of his Museum years came one after another. In 1827, while examining grains of pollen of Clarkia pulchella suspended in water under the microscope, he observed that the smallest particles in the suspension underwent an incessant random jiggling motion that could not be explained by any current of the water or by any vital action of the pollen; he published the observation in 1828, and it has been known since as Brownian motion. The phenomenon was given its modern mechanical explanation as the random thermal bombardment of the particles by water molecules by Einstein in 1905 and by Marian Smoluchowski in 1906, and the experimental confirmation by Jean Perrin in 1908 became one of the foundational proofs of the molecular theory of matter.

In 1831 he addressed the Linnean Society on the cellular structure of orchids and in a passing remark described, and named for the first time in English, the nucleus of the plant cell, the small dense body within the cell that he had observed in the epidermis of every species he had examined; the term and the concept entered cell biology directly from his lecture. He died at his house in Dean Street, Soho on the tenth of June 1858, in his eighty-fifth year, and was buried in Kensal Green cemetery. The Brown name in modern science carries the weight of the Soho microscope under which the cell nucleus was first named and the dance of pollen-water particles was first described.