From Today in Science History:
John Gould (Born 14 Sep 1804; died 3 Feb 1881). English ornithologist whose life work produced 41 lavishly illustrated volumes on birds from all over the world, containing in all about 3,000 plates, all lithographed and hand-painted. Of these, his Birds of Australia was particularly significant (1840-69) as the first comprehensive record of the continent’s birds and mammals. With its plates of the birds were descriptions, notes on their distribution and adaptation to the environment. He assisted Charles Darwin with identification of the specimens collected during the voyage of the Beagle. By informing Darwin that the finches belonging to separate species, he provided essential information giving Darwin insight leading to his later development of the theory of evolution.
Alexander von Humboldt (Born 14 Sep 1769; died 6 May 1859). (Baron) Friedrich Wilhelm Heinrich Alexander von Humboldt was a German natural scientist, archeologist, explorer and geographer, who made two major expeditions to Latin America (1799-1804) and to Asia (1829). During the first, equipped with the best scientific instruments, he surveyed and collected geological, zoological, botanical, and ethnographic specimens, including over 60,000 rare or new tropical plants. He charted and made observations on a cold ocean current along the Peruvian coast, now named, the Humboldt Current. In geology, he made pioneering observations of stratigraphy, structure and geomorphology; he understood the connections between volcanism and earthquakes. Humboldt named the Jurassic System.
Charles Valentine Riley (Died 14 Sep 1895; born 18 Sep 1843). British-born American entomologist who pioneered the scientific study of insects for their economic impact in agriculture. He was a keen observer of relationships in nature, and enhanced his written observations with drawings. He initiated biological control. After studying the parasites and predators of the cottony cushion scale, which was destroying the citrus industry in California, he introduced (1888) a natural enemy of the scale from Australia. The effectiveness of the Vedalia cardinalis beetle in reducing the populations of the cottony cushion scale promoted the study of biological control of pests. He helped establish the Division of Entomology of the U.S. Department of Agriculture.