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614 to the observatory. From the first meeting of this commission Prof. Newcomb has acted as secretary thereof. Prof. Newcomb's most recent labors have been on the motion of the moon, and the possible variability of the sidereal day, on which subject he has published several fragmentary discussions. Hansen's tables of the moon have deviated from observation for several years past in a remarkable manner, and he has accounted for the changes by an acceleration in the rotation of the earth on its axis. It is now considered that he has proved the actual existence of this acceleration beyond reasonable doubt.

In February, 1874, he was the recipient of the gold medal of the Royal Astronomical Society of Great Britain. The presentation was preceded by an address by the president, Prof. Cayley, in which, after giving an account of several of Prof. Newcomb's most important contributions to mathematical science, he says: "They exhibit all of them a combination, on the one hand, of mathematical skill and power, and, on the other hand, of good hard work, devoted to the furtherance of astronomical science." Thus, though belonging to the younger generation of astronomers, Prof. Newcomb has received his full share of honors, both at home and abroad. Graduating as B. S. at Harvard University, in 1858, he is now, at home, member of the National Academy of Science, and of the American Academy of Arts and Sciences, in Boston. In 1 876 he was elected President of the American Association for the Advancement of Science, and presides at its annual meeting, in Nashville, in August of this year. In 1874 he received the honorary degree of LL. D. from the Columbian University, at Washington, and in 1875 the same honor from Yale. Abroad, he was, in 1872, elected associate member of the Royal Astronomical Society of Great Britain; in 1874, corresponding member of the Institut de France; in 1875 he received the honorary degree of Ph. D. from the University of Leyden, at its three-hundredth anniversary. Also in that year he was made a member of the Imperial Academy of Sciences of St. Petersburg, member of the Royal Swedish Academy of Sciences, and member of the Royal Bavarian Academy of Sciences.