icipated in the first discoveries passed away without witnessing
their resumption. In 1830, however, a certain Hencke, ex-postmaster in
the Prussian town of Driessen, set himself to watch for new planets, and
after fifteen long years his patience was rewarded. The asteroid found
by him, December 8, 1845, received the name of Astraea, and his further
prosecution of the search resulted, July 1, 1847, in the discovery of
Hebe. A few weeks later (August 13), John Russell Hind (1823-1893),
after many months' exploration from Mr. Bishop's observatory in the
Regent's Park, picked up Iris, and October 18, Flora.[212] The next on
the list was Metis, found by Mr. Graham, April 25, 1848, at Markree, in
Ireland.[213] At the close of the period to which our attention is at
present limited, the number of these small bodies known to astronomy was
thirteen; and the course of discovery has since proceeded far more
rapidly and with less interruption.

Both in itself and in its consequences the recognition of the minor
planets was of the highest importance to science. The traditional ideas
regarding the constitution of the solar system were enlarged by the
admission of a new class of bodies, strongly contrasted, yet strictly
co-ordinate with the old-established planetary order; the profusion of
resource, so conspicuous in the living kingdoms of Nature, was seen to
prevail no less in the celestial spaces; and some faint preliminary
notion was afforded of the indefinite complexity of relations underlying
the apparent simplicity of the majestic scheme to which our world
belongs. Both theoretical and practical astronomy derived profit from
the admission of these apparently insignificant strangers to the rights
of citizenship of the solar system. The disturbance of their motions by
their giant neighbours afforded a more accurate knowledge of the Jovian
mass, which Laplace had taken about 1/50 too small; the anomalous
character of their orbits presented geometers with highly stimulating
problems in the theory of perturbation; while the exigencies of the
first discovery had produced the _Theoria Motus_, and won Gauss over to
the ranks of calculating astronomy. Moreover, the sure prospect of
further detections powerfully incited to the exploration of the skies;
observers became more numerous and more zealous in view of the prizes
held out to them; star-maps were diligently constructed, and the
sidereal multitude strewn along the great zodiacal bel