RIDDELL, John Leonard, physician, born in Leyden, Massachusetts, 20 February, 1807; died in New Orleans, Louisiana, 7 October, 1867. He was graduated at Rensselaer institute, in Troy, New York, and in 1835 at, the Medical college of Cincinnati, where he became professor of botany and adjunct professor of chemistry. He occupied the chair of chemistry in the medical department of the University of Louisiana from 1836 till 1865. Dr. Riddell was melter and refiner at the United States mint in New Orleans, the inventor of a binocular microscope and magnifying-glass, and discovered the microscopical characteristics of the blood and black vomit in yellow fever, he first brought to notice the botanical genus "Riddellia," which was named for him. He contributed to the " London Microscopical Journal," the " American Journal of Science and Arts," and other periodicals, and published " Synopsis of the Flora of the Western States" (Cincinnati, 1835); " Memoir advocating the Organic Nature of Miasm and Contagion " (1836); "A Monograph on the Silver Dollar" (New Orleans. 1845)" "A Memoir on the Constitution of Matter" (1847) ; and a " Report on the Epidemic of 1853 " (1854).