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