Denison Olmsted, an American natural philosopher, born in East Hartford, Conn., June 18, 1791, died in New Haven, May 13, 1859. He graduated at Yale college in 1809, and almost immediately took charge of the union school at New London. In 1815 he became a tutor in Yale college, and in 1817 was appointed professor of chemistry, mineralogy, and geology in the university of North Carolina. Here he proposed and executed the first state geological survey ever attempted in this country, the report of which was published in 1824 and 1825. In the latter year he was appointed professor of mathematics and natural philosophy in Yale college; in 1836 the professorship was divided at his request, and he retained the department of natural philosophy. Between 1831 and 1843 he published several text books on natural philosophy and astronomy, which were widely used. As early as 1830 he had published an elaborate theory of hail storms, which called forth much discussion, but finally received the general approbation of meteorologists. After the shower of shooting stars which fell in November, 1833, he investigated their history and phenomena for many years, till he had demonstrated their cosmical origin.

He made a series of observations on the aurora borealis, the results of which are given in vol. viii. of the "Smithsonian Contributions to Knowledge." He made numerous mechanical inventions, very few of which were secured by patent. One was the Olmsted stove.