the new war balloons, 30,000 miles long and 7,000 miles across. The
next year it was brick-red. A white spot beside it completed a
rotation in less time by 5-1/2 minutes than the red spot--a difference
of 260 miles an hour. Thus they came together again every six weeks,
but the motions did not continue uniform. The spot was feeble in
1882-4, brightened in 1886, and, after many changes, is still visible.

Galileo's great discovery of Jupiter's four moons was the last word in
this connection until September 9th, 1892, when Barnard, using the
36-inch refractor of the Lick Observatory, detected a tiny spot of
light closely following the planet. This proved to be a new satellite
(fifth), nearer to the planet than any other, and revolving round it
in 11h. 57m. 23s. Between its rising and setting there must be an
interval of 2-1/2 Jovian days, and two or three full moons. The sixth
and seventh satellites were found by the examination of photographic
plates at the Lick Observatory in 1905, since which time they have
been continuously photographed, and their orbits traced, at Greenwich.
On examining these plates in 1908 Mr. Melotte detected the eighth
satellite, which seems to be revolving in a retrograde orbit three
times as far from its planet as the next one (seventh), in these two
points agreeing with the outermost of Saturn's satellites (Phoebe).

_Saturn._--This planet, with its marvellous ring, was perhaps the most
wonderful object of those first examined by Galileo's telescope. He
was followed by Dominique Cassini, who detected bands like Jupiter's
belts. Herschel established the rotation of the planet in 1775-94.
From observations during one hundred rotations he found the period to
be 10h. 16m. 0s., 44. Herschel also measured the ratio of the polar to
the equatoreal diameter as 10:11.