Adams's friends felt that he had not received from either of the astronomers, to whom he confided his results, the kind of help or advice he should have received. Challis was kindly, but wanting in initiative. Although he had command of the great Northumberland telescope, he had no thought of commencing the search in 1845, for, without mistrusting the evidence which the theory gave of the _existence_ of the planet, it might be reasonable to suppose that its position was determined but roughly, and that a search for it must necessarily be long and laborious. In the view of Simon Newcomb,[3] Adams's results, which were delivered at the Greenwich Observatory October 21, 1845, were so near to the mark that a few hours' close search could not have failed to make the planet known. Both Adams and Leverrier had assumed as a rough approximation at starting that the orbit of the new planet was circular and that, in accordance with Bode's Law, its distance was twice that of Uranus. S. C. Walker, of the Smithsonian Institution, Washington, was able to determine the elements of the orbit of Neptune accurately in 1847. In February of that year he had found (as had Petersen of Altona about the same time) that Lalande had in May, 1795, observed Neptune and mistaken it for a fixed star. When Lalande's records in Paris were studied, it was found that he had made two observations of Neptune on May 8 and 10. Their failure to agree caused the observer to reject one and mark the other as doubtful. Had he repeated the observation, he might have noted that the _star_ moved, and was in reality a planet. Neptune's orbit is more nearly circular than that of any of the major planets except Venus. Its distance is thirty times that of the earth from the sun instead of thirty-nine times, as Bode's Law would require. That generalization was a presupposition of the calculations leading to the discovery. It was then rejected like a discredited ladder. Man's conception of the universe is widened at the thought that the outmost known planet of our solar system is about 2,796,000,000 miles from the sun and requires about 165 years for one revolution. Professor Peirce, of Harvard University, pointing to the difference between the calculations of Leverrier and the facts, put forward the view that the discovery made by Galle must be regarded as a happy accident. This view, however, has not been sustained. REFERENCES Sir Robert Ball, Neptune's Jubilee Year, _Scientific American_, Supplement, Oct. 10, 1896. Sir Robert Ball, _The Story of the Heavens_, chap. XV. B. A. Gould, _Report on the History of the Discovery of Neptune, Smithsonian Contributions to Knowledge_, 1850. Robert Grant, _History of Physical Astronomy_. Simon Newcomb, _Popular Astronomy_. Benjamin Peirce, _Proceedings of the American Academy of Arts and Sciences_, vol. I, pp. 57-68, 144, 285, 338-41, etc. FOOTNOTES: [3] See article "Neptune," _Encyc. Brit._ CHAPTER XV