Page:Popular Science Monthly Volume 41.djvu/563

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SKETCH OF JOHN COUCH ADAMS.

that part of the zone in the immediate neighborhood of the place indicated by theory. Unfortunately, the observations were not immediately compared with each other, or Prof. Challis would have discovered, what he afterward found to be the case, that he had actually seen the planet on August 4th and August 12th, the third and fourth nights of observation.... On September 3, 1846, Adams communicated to the astronomer royal a new solution of the problem, supposing the mean distance of the planet as originally assumed, to be diminished by about the thirtieth part. The result of this change was to produce a better agreement between the theory and the later observations, and to give a smaller and therefore a more probable value of the eccentricity."

Leverrier's first paper relative to the subject was presented to the French Academy on November 10, 1845, and concerned the perturbations of Uranus produced by Jupiter and Saturn; but in it he also pointed to irregularities which could not be accounted for by the existing theory. In his second paper, June 1, 1846, he expressed the conclusion that the unexplained irregularities were due to an undiscovered planet exterior to Uranus. He calculated the longitude, but did not give the elements of the orbit of the disturbing planet. The place assigned by him to the supposed body differed by only one degree from that given by Adams in the paper which he had left at the Greenwich Observatory seven months earlier.

"Adams's researches," says Prof. Glaisher, "therefore preceded Leverrier's by a considerable interval; and in spite of the delay in carrying out the search, it had been carried on at Cambridge for nearly two months before the planet was found at Berlin. Adams's investigation may be regarded as having been completed on October 21, 1845, when he left his paper at the Royal Observatory. This was three weeks before Leverrier's memoir, showing that the irregularities could not be attributed to any of the known planets, was presented to the French Academy, and more than seven months before the presentation of Leverrier's second memoir. It is to be noticed that in this second memoir Leverrier did not give the elements of the orbit or the mass of the planet, which were contained in Adams's paper of October 21st."

A bitter controversy ensued over the question of priority in discovery, in which Mr. Adams took no part. He felt and expressed a warm appreciation for Leverrier; met him with great pleasure at Oxford in 1847; and was visited by him in the same year at Cambridge. A story was told of him for the first time by Dr. Donald MacAlister at the commemorative meeting at St. John's College, February 20, 1892, to the effect that several years ago, when a memorial volume was prepared to be presented to M. Pasteur as a testimonial of the appreciation of English men of