 In 1845 he was chosen professor of chemistry and natural history in Amherst, which chair was divided in 1852, and he continued to deliver the lectures on natural history until 1877, when he was made professor emeritus.He was associated in 1835 with James G. Percival in the geological survey of Connecticut, and throughout his life he was actively engaged in the study of mineralogy.He announced in 1835 his discovery of his first new species of microlite, that of warwickite in 1838, that of danburite in 1839, and he afterward described many other new minerals until shortly before his death.