ver, have been separated from
one original mass by the divellent action of the sun at close quarters.
Each has doubtless its own period, since each has most likely suffered
retardations or accelerations special to itself, which, though trifling
in amount, would avail materially to alter the length of the major axis,
while leaving the remaining elements of the common orbit virtually
unchanged.[1324]

A fifth member was added to the family in 1887. On the 18th of January
in that year, M. Thome discovered at Cordoba a comet reproducing with
curious fidelity the lineaments of that observed in the same latitudes
seven years previously. The narrow ribbon of light, contracting towards
the sun, and running outward from it to a distance of thirty-five
degrees; the unsubstantial head--a veiled nothingness, as it appeared,
since no distinct nucleus could be made out; the quick fading into
invisibility, were all accordant peculiarities, and they were confirmed
by some rough calculations of its orbit, showing geometrical affinity to
be no less unmistakable than physical likeness. The observations secured
were indeed, from the nature of the apparition, neither numerous nor
over-reliable; and the earliest of them dated from a week after
perihelion, passed, almost by a touch-and-go escape, January 11. On
January 27, this mysterious object could barely be discerned
telescopically at Cordoba.[1325] That it belonged to the series of
"southern comets" can scarcely be doubted; but the inference that it was
an actual return of the comet of 1880, improbable in itself, was
negatived by its non-appearance in 1894. Meyer's incorporation with this
extraordinary group of the "eclipse-comet" of 1882[1326] has been
approved by Kreutz, after searching examination.

The idea of cometary systems was first suggested by Thomas Clausen in
1831.[1327] It was developed by the late M. Hoek, director of the
Utrecht Observatory, in 1865 and some following years.[1328] He found
that in quite a considerable number of cases, the paths of two or three
comets had a common point of intersection far out in space, indicating
with much likelihood a community of origin. This consisted, according to
his surmise, in the disruption of a parent mass during its sweep round
the star latest visited. Be this as it may, the fact is undoubted that
numerous comets fall into groups, in which similar conditions of motion
betray a pre-existent physical connection. Never before, howe