From Today in Science History:
Sir William Jackson Hooker (Born 6 July 1785; died 12 Aug 1865). English botanist who was the first director of the Royal Botanic Gardens at Kew, near London. He greatly advanced the knowledge of ferns, algae, lichens, and fungi, as well as of higher plants. [Father to botanist Joseph Dalton Hooker]
Alexander Wilson (Born 6 July 1766; died 23 Aug 1813). Scottish-born ornithologist and poet who left his homeland in 1794, aged 27, in search of a better life in America. Naturalist William Bartram sparked his interest in birds. By 1802, Wilson had resolved to author a book illustrating every North American bird. He travelled extensively to make paintings of the birds he observed. This pioneering work on North American birds grew to nine volumes of American Ornithology, published between 1808 and 1814, with illustrations of 268 species, of which 26 were new. As a founder of American ornithology he became one of the leading naturalists who also made the first census of breeding birds, corrected errors of taxonomy, and may have inspired Audubon’s later work when they met in 1810.
Joseph LeConte (Died 6 July 1901; born 26 Feb 1823). American geologist who was a universalist in the scope of his scientific writings. As a founding member of John Muir’s Sierra Club, he spoke fervently for broad preservation of California forests by government and wise use of timberlands in private enterprise. He was one of the earliest advocates of contractional theory of mountain formation. LeConte accepted the theory of evolution about 1874, becoming one of its leading proponents and a writer able to reconcile the idea with religious thought. His Sight: An Exposition of the Principles of Monocular and Binocular Vision (1881) was the first treatise on physiological optics written in the U.S. He was an ardent camper, and his death occurred during a trip in the Yosemite Valley.