han any of the previously known satellites. In accordance with the
general law, that the nearer the satellite the shorter the period of
revolution, Herschel found that this little moon completed a revolution
in about 1 day, 8 hours, 53 minutes. The same great telescope, used with
the same unrivalled skill, soon led Herschel to a still more interesting
discovery. An object so small as only to appear like a very minute
point in the great forty-foot reflector was also detected by Herschel,
and was by him proved to be a satellite, so close to the planet that it
completed a revolution in the very brief period of 22 hours and 37
minutes. This is an extremely delicate object, only to be seen by the
best telescopes in the brief intervals when it is not entirely screened
from view by the ring.

Again another long interval elapsed, and for almost fifty years the
Saturnian system was regarded as consisting of the series of rings and
of the seven satellites. The next discovery has a singular historical
interest. It was made simultaneously by two observers--Professor Bond,
of Cambridge, Mass., and Mr. Lassell, of Liverpool--for on the 19th
September, 1848, both of these astronomers verified that a small point
which they had each seen on previous nights was really a satellite. This
object is, however, at a considerable distance from the planet, and
requires 21 days, 7 hours, 28 minutes for each revolution; it is the
seventh in order from the planet.

Yet one more extremely faint outer satellite was discerned by
photography on the 16th, 17th, and 18th August, 1898, by Professor W.H.
Pickering. This object is much more distant from the planet than the
larger and older satellites. Its motion has not yet been fully
determined, but probably it requires not less than 490 days to perform a
single revolution.

From observations of the satellites it has been found that 3,500 globes
as heavy as Saturn would weigh as much as the sun.

A law has been observed by Professor Kirkwood, which connects together
the movements of the four interior satellites of Saturn. This law is
fulfilled in such a manner as leads to the supposition that it arises
from the mutual attraction of the satellites. We have already described
a similar law relative to three of the satellites of Jupiter. The
problem relating to Saturn, involving as it does no fewer than four
satellites, is one of no ordinary complexity. It involves the theory of
Perturbations to a greater