He occupied the post of professor of natural philosophy and chemistry in the University of Pennsylvania in 1828-1841 and in 1842-1843. For the trustees of what in 1848 was to become Girard College, but had not yet been opened, he spent the years 1836-1838 in Europe, examining European systems of education, and on his return published a very valuable report. In 1843, on the death of Professor Ferdinand Rudolph Hassler (1770-1843), he was appointed superintendent of the United States coast survey.
He succeeded in impressing United States Congress with a sense of the great value of this work, and by means of the liberal aid it granted, he carried out a singularly comprehensive plan with great ability and most satisfactory results. By a skilful division of labour, and by the erection of numerous observing stations, the mapping out of the whole coast proceeded simultaneously under the eye of the general director, and in addition a vast mass of magnetic and meteorological observations was collected. He died at Newport, Rhode Island, on the February 17, 1867.