curvature
perceptible; the edges of the appendage ran parallel, forming a nebulous
causeway from star to star; and the comparison to an auroral beam was
appropriately used. The aspect of the famous comet of 1843 was forcibly
recalled to the memory of Mr. Janisch, Governor of St. Helena; and the
resemblance proved not merely superficial. But the comet of 1880 was
less brilliant, and even more evanescent. After only eight days of
visibility, it had faded so much as no longer to strike, though still
discoverable by the unaided eye; and on February 20 it was invisible
with the great Cordoba equatoreal pointed to its known place.

But the most astonishing circumstance connected with this body is the
identity of its path with that of its predecessor in 1843. This is
undeniable. Dr. Gould,[1283] Mr. Hind, and Dr. Copeland,[1284] each
computed a separate set of elements from the first rough observations,
and each was struck with an agreement between the two orbits so close as
to render them virtually indistinguishable. "Can it be possible," Mr.
Hind wrote to Sir George Airy, "that there is such a comet in the
system, almost grazing the sun's surface in perihelion, and revolving in
less than thirty-seven years. I confess I feel a difficulty in admitting
it, notwithstanding the above extraordinary resemblance of
orbits."[1285]

Mr. Hind's difficulty was shared by other astronomers. It would, indeed,
be a violation of common-sense to suppose that a celestial visitant so
striking in appearance had been for centuries back an unnoticed
frequenter of our skies. Various expedients, accordingly, were resorted
to for getting rid of the anomaly. The most promising at first sight was
that of the resisting medium. It was hard to believe that a body,
largely vaporous, shooting past the sun at a distance of less than a
hundred thousand miles from his surface, should have escaped powerful
retardation. It must have passed through the very midst of the corona.
It might easily have had an actual encounter with a prominence. Escape
from such proximity might, indeed, very well have been judged beforehand
to be impossible. Even admitting no other kind of opposition than that
dubiously supposed to have affected Encke's comet, the result in
shortening the period ought to be of the most marked kind. It was proved
by Oppolzer[1286] that if the comet of 1843 had entered our system from
stellar space with parabolic velocity it would, by the action of a