Dr. Perkins, the Professor of Materia Medica, removed to New York after the dissolution of the "University of New Hampshire," and the late admired and lamented Dr. Daniel Oliver, of Salem, was appointed to the professorship. Dr. Mussey, celebrated for his surgical knowledge and skill, remained as the head of the Medical School, and among these gentlemen, differing widely as they did in many characteristics, the warmest friendship subsisted. During the intervals of leisure from strictly professional duties, Dr. Dana occupied himself in continuing to write for "Silliman's Journal," and in frequent excursions to various parts of New Hampshire, for the purpose of analyzing the ores and waters of mines and springs. His published analysis of the waters of a spring in Burton, N. H., was considered so scientific a production, that he was written to as to accepting a professorship in the University of Virginia. Not wishing the appointment, he declined becoming a candidate. In the latter part of 1825, Professor Dana published "An Epitome of Chemical Philosophy," designed as a text-book for his own classes, but which was afterwards adopted as such in two other institutions. In 1826, he was appointed one of the visitors of West Point Military Academy, and soon after his return was chosen to the chair of Chemistry, in the College of Physicians and Surgeons in the University of New York, to which city he then removed. He was elected member of the Linnæan Society of New York, and accepted an invitation to deliver a course of lectures before the Athenæeum. During his residence at Hanover, Professor Dana had been much interested in Electro-magnetism, then a new science, and in preparing apparatus for exhibiting its wonders, freely stating his conviction that it would produce more astonishing results than any power previously known. When surprise was expressed at his selecting for his Athenæeum lectures this subject, so little known even in Europe, and in which so few in this country would feel any interest, Dr. Dana replied that he had chosen it for those reasons; that he thought it time for public attention to be directed to it, as he was certain it would lead to most valuable results, and that he should endeavor to render it popular. How far he succeeded, the delighted audiences that crowded to hear him bore evidence. Of the truth of his prediction as to the results to be wrought out by the science, the marvels of the electro-magnetic telegraph bear witness to the world. Samuel F. B. Morse was then following his profession as a painter in New York, and lectured upon art before the Athenæeum. An intimacy sprang up between him and Dr. Dana, whose lectures he attended, and whom he used to visit in his laboratory, thus becoming familiar with his views on scientific subjects. Morse's published statements as to the origin of his knowledge of electro-magnetism are as follows: