This collection includes the full range of Henry's activities from 1825 through 1878, although the years after he became Secretary in 1846 are more fully represented than those before. Henry carried on correspondence with many of the great scientific men of his day, and the correspondence runs the gamut from details of scientific research to the broadest questions of scientific policy and the growth of professional scientific organizations. Henry's work in electromagnetism is documented, as is his role in the development of the telegraph; and the many papers and addresses he gave on scientific, educational, and other topics are an important resource. His work in meteorology can be studied here and in the Meteorological Project records. A considerable segment of the papers deals with the United States Lighthouse Board, to which Henry was appointed in 1852, and with the American Association for the Advancement of Science, the National Academy of Sciences, and the Philosophical Society of Washington. One of Henry's daughters, Mary A. Henry, compiled extensive information for a biography of her father, which is also included in the Henry collection.