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SKETCH OF DENISON OLMSTED.

and theoretical ones on meteorology. His colleagues and friends have regarded him as a born teacher, as possessing a most happy union of several powers—the capacity to convey instruction with clearness and evidence, the capacity to impress the pupil with the importance of the branches taught, the disposition to shrink from no labor necessary in preparing himself for teaching, and to require of the student that he master and reproduce the lessons conveyed to him. While many lecturers prepare their lectures once for all, and then cease to improve them, he was constantly revising, elaborating, and almost constructing anew the courses on astronomy and meteorology which he delivered annually to the three upper classes." These lectures were spoken of by Dr. Barnard, in his Journal of Education, as having been characterized "by fullness, clearness of method, and sometimes by eloquence. The course on meteorology was, perhaps, on the whole, the most attractive and useful."

Prof. Olmsted soon became sensible of the deficiency of the textbooks on which he had to rely in his department. Enfield's Philosophy was inaccurate and behind the state of science; and the work of Prof. Farrar, of Cambridge, was too extensive and too difficult. He undertook to prepare new books suitable for his classes. His Natural Philosophy appeared in 1831, and his School Philosophy in 1833. His Astronomy, first published in 1839, went through forty or fifty editions. An edition of it was printed in raised letters for the blind, it having been selected by Dr. Howe, according to Dr. Barnard, "for its clear, accurate, comprehensive presentation of the science of which it treats." The Rudiments of Natural Philosophy and Astronomy followed, in 18-42. The Letters on Astronomy was a work in more familiar style, cast in the form of letters to a lady, and prepared as a reading book for the school libraries established by the Massachusetts Board of Education.

The great meteoric shower of November, 1833, which was observed over a large part of the American continent and on the ocean, directed Prof. Olmsted's mind to a new and original field of investigation; and several papers upon it were published by him and Prof. A. C Twining, of West Point, in the American Journal of Science during 1834. The collation of the collected observations brought out the fact that the apparent point of radiation of the meteors was identical with that toward which the earth was tending in space—which indicated a cosmical origin. It was further found that several showers had been observed before within forty years, on the same day of November. In explanation of the phenomenon. Prof. Olmsted supposed, in an article published in the American Journal of Science, that the meteors "consisted of portions of the extreme parts of a nebulous