observations; the boy's work, like that of the man afterward, was almost entirely internal and mental. Thus, at the age of twenty-seven, his schooling was ended, and he left his home and went to Missouri to teach. Failing health compelled him to stop work for a time, and his next engagement was at a small school in Kentucky, where he remained for seven years, until 1854.
While in Missouri he had happened on a copy of Newton's Principia, ordered but never called for by an earlier teacher; he bought it for five dollars, making little advance then on account of poor health, but later returned to it in Kentucky. "I now became first interested in the tides, and conceived the idea that the action of the moon and sun must have a tendency to retard the earth's rotation on its axis. Knowing that Laplace had treated the subject extensively in the Mécanique Céleste, I was very desirous of obtaining a copy, mostly to see what he had in that subject. I accordingly instructed a village merchant, on going to Philadelphia for a supply of goods, to procure me the work, having little idea of the magnitude of the work or the cost. On learning the cost at Philadelphia, he did not procure it for me until after writing and hearing further from me. I had now plenty to study in connection with my teaching for several years." From this followed Ferrel's first scientific paper. On the Effect of the Sun and Moon on the Rotary Motion of the Earth, a subject to which he returned with success in later years.
In the spring of 1854 Ferrel went to Nashville, Tenn., and opened a private school; here Prof. W. K. Bowling, of the Medical College, became his warm friend, and here he first turned his attention to meteorology, from meeting with Maury's Physical Geography of the Sea. "From this book I first learned that the atmospheric pressure was greatest near the parallels of 30°, and less at the equator and in the polar regions; and I at once commenced to study the cause of it. . . . In conversation one day with my friend Dr. Bowling, I told him I had read Maury's book, and he was at once desirous of knowing what I thought of it. I told him that I did not agree with Maury in many things. He then desired me to 'pitch into him,' as he expressed it, and furnish a review for his Journal of Medicine. This I declined to do, but at length consented to furnish an essay on certain subjects treated in the book, and notice Maury's views a little in an incidental way." This was the beginning of the studies in meteorology, which gave a new aspect to the science. The promised article was his Essay on the Winds and Currents of the Ocean. It has since been republished by the Signal Service in Professional Paper No. XII.
In the spring of 1857 the third period of Ferrel's life began on his accepting an offer from Prof. Winlock, transmitted through Dr. B. A. Gould, to take part in the computations for the Nauti-
