The Correspondence Series contains letters and supporting documents received from family, friends, colleagues, students and clients. Correspondence that had been collected in annual files was rearranged alphabetically by correspondent to facilitate access. Major correspondent files are arranged chronologically. Correspondence from family members makes up a large portion of the material. Eben’s parents, Jerediah and M. C. Horsford, wrote frequently as did Eben’s sisters, Julia Norton and Eliza Tryon, and cousin, Eliza Norton. Illness and medical treatment discussed in the family correspondence is particularly detailed. Politics, religion and education are also frequent topics of discussion. The broad and varied interests of Eben Norton Horsford are represented in correspondence with a large number of people. Subjects include: the American Academy of Arts & Science, explosion of burning fluid, patents, artificial manure, Focault pendulum experiments, India rubber, lead poisoning, gutta percha, water analysis, water systems, bleaching processes, science education, spiritualism, geological surveys, hydropathy and the Smithsonian Institute. Noteworthy correspondents include: James Hall, E. B. Hunt, Louis Agassiz, Joseph Lovering, Justus von Liebig, Alexander Graham Bell, Samuel Morse, Jared Sparks, Edward Everett, and Benjamin Gould.