invisibility previous to 1892, when it was evidently in a state of
peculiar excitement. Mr. Perrine was barely able, with the Lick 36-inch,
to find the vague nebulous patch which occupied its predicted place on
June 10, 1899.

The origin of comets has been long and eagerly inquired into, not
altogether apart from the cheering guidance of ascertained facts. Sir
William Herschel regarded them as fragments of nebulae[1362]--scattered
debris of embryo worlds; and Laplace approved of and adopted the
idea.[1363] But there was a difficulty. No comet has yet been observed
to travel in a decided hyperbola. The typical cometary orbit, apart from
disturbance, is parabolic--that is to say, it is indistinguishable from
an enormously long ellipse. But this circumstance could only be
reconciled with the view that the bodies thus moving were casual
visitors from outer space, by making, as Laplace did, the tacit
assumption that the solar system was at rest. His reasoning was, indeed,
thereby completely vitiated, as Gauss pointed out in 1815;[1364] and the
objections then urged were reiterated by Schiaparelli,[1365] who
demonstrated in 1871 that a large preponderance of well-marked
hyperbolic orbits should result if comets were picked up _en route_ by a
swiftly-advancing sun. The fact that their native movement is
practically parabolic shows it to have been wholly imparted from
without. They passively obeyed the pull exerted upon them. In other
words, their condition previous to being attracted by the sun was one
very nearly of relative repose.[1366] They shared, accordingly, the
movement of translation through space of the solar system.

This significant conclusion had been indicated, on other grounds, as the
upshot of researches undertaken independently by Carrington[1367] and
Mohn[1368] in 1860, with a view to ascertaining the anticipated
existence of a relationship between the general _lie_ of the paths of
comets and the direction of the sun's journey. It is tolerably obvious
that if they wander at haphazard through interstellar regions their
apparitions should markedly aggregate towards the vicinity of the
constellation Lyra; that is to say, we should meet considerably more
comets than would overtake us, for the very same reason that falling
stars are more numerous after than before midnight. Moreover, the comets
met by us should be, apparently, swifter-moving objects than those
coming up with us from behind; because, in the one c