That, instead of the orbit of Neptune agreeing with the calculations of Adams and Leverrier, it was so different--that Leverrier said that it was not the planet of his calculations. Later it was thought best to say no more upon that subject. The text-books omit this: That, in 1846, everyone who knew a sine from a cosine was out sining and cosining for a planet beyond Uranus. Two of them guessed right. To some minds, even after Leverrier's own rejection of Neptune, the word "guessed" may be objectionable--but, according to Prof. Peirce, of Harvard, the calculations of Adams and Leverrier would have applied quite as well to positions many degrees from the position of Neptune. Or for Prof. Peirce's demonstration that the discovery of Neptune was only a "happy accident," see _Proc. Amer. Acad. Sciences_, 1-65. For references, see Lowell's _Evolution of Worlds_. Or comets: another nebulous resistance to our own notions. As to eclipses, I have notes upon several of them that did not occur upon scheduled time, though with differences only of seconds--and one delightful lost soul, deep-buried, but buried in the ultra-respectable records of the Royal Astronomical Society, upon an eclipse that did not occur at all. That delightful, ultra-sponsored thing of perdition is too good and malicious to be dismissed with passing notice: we'll have him later. Throughout the history of astronomy, every comet that has come back upon predicted time--not that, essentially, there was anything more abstruse about it than is a prediction that you can make of a postman's periodicities tomorrow--was advertised for all it was worth. It's the way reputations are worked up for fortune-tellers by the faithful. The comets that didn't come back--omitted or explained. Or Encke's comet. It came back slower and slower. But the astronomers explained. Be almost absolutely sure of that: they explained. They had it all worked out and formulated and "proved" why that comet was coming back slower and slower--and there the damn thing began coming faster and faster. Halley's comet. Astronomy--"the perfect science, as we astronomers like to call it." (Jacoby.) It's my own notion that if, in a real existence, an astronomer could not tell one longitude from another, he'd be sent back to this purgatory of ours until he could meet that simple requirement. Halley was sent to the Cape of Good Hope to determine its longitude. He got it degrees wrong. He gave to Africa's noble Roman promontory a retrousse twist that would take the pride out of any Kaffir. We hear everlastingly of Halley's comet. It came back--maybe. But, unless we look the matter up in contemporaneous records, we hear nothing of--the Leonids, for instance. By the same methods as those by which Halley's comet was predicted, the Leonids were predicted. November, 1898--no Leonids. It was explained. They had been perturbed. They would appear in November, 1899. November, 1899--November, 1900--no Leonids.