tude imprinted itself on a plate exposed by
Herr Witt at the Urania Observatory, Berlin. Its originator proved to be
unique among asteroids. "Eros" is, in sober fact,

'one of those mysterious stars
Which hide themselves between the Earth and Mars,'

divined or imagined by Shelley.[1015] True, several of its congeners
invade the Martian sphere at intervals; but the proper habitat of Eros
is within that limit, although its excursions transcend it. In other
words, its mean distance from the sun is about 135, as compared with the
Martian distance of 141 million miles. Further, its orbit being so
fortunately circumstanced as to bring it once in sixty-seven years
within some 15 millions of miles of the earth, it is of extraordinary
value to celestial surveyors. The calculation of its movements was much
facilitated by detections, through a retrospective search,[1016] of many
of its linear images among the star-dots on the Harvard plates.[1017]
The little body--which can scarcely be more than twenty miles in
diameter--shows peculiarities of behaviour as well as of position. Dr.
von Oppolzer, in February, 1901,[1018] announced it to be extensively
and rapidly variable. Once in 2 hours 38 minutes it lost about
three-fourths of its light,[1019] but these fluctuations quickly
diminished in range, and in the beginning of May ceased
altogether.[1020] Evidently, then, they depend upon the situation of the
asteroid relatively to ourselves; and, so far, events lent countenance
to M. Andre's eclipse hypothesis, since mutual occultations of the
supposed planetary twins could only take place when the plane of their
revolutions passed through the earth, and this condition would be
transitory. Yet the recognition in Eros of an "Algol asteroid" seems on
other grounds inadmissible;[1021] nor until the phenomenon is
conspicuously renewed--as it probably will be at the opposition of
1903--can there be much hope of finding its appropriate rationale.

The crowd of orbits disclosed by asteroidal detections invites attentive
study. D'Arrest remarked in 1851,[1022] when only thirteen minor planets
were known, that supposing their paths to be represented by solid hoops,
not one of the thirteen could be lifted from its place without bringing
the others with it. The complexity of interwoven tracks thus illustrated
has grown almost in the numerical proportion of discovery. Yet no two
actually intersect, because no two lie exactly