366 OF THE PHÆNOMENA AND AFFECTIONS

same part oshis surface, and has been occasionallyseen ever since. It has been conjectured thatthese belts are seas, and that the variations ob-served, both in them and the spots, are occa-sioned by tides, which are differently affectedaccording to the positions of his moons. Thefour satellites of Jupiter were first observed byGalileo, the 7th of January 1610, soon after theinvention of the telescope, but the belts werenot discovered till near twenty years afterwards.

Saturn is at too great a distance for us to dis-tinguish those varieties which it is probable areupon his surface ; but the faint appearance of abelt may sometimes be seen, resembling those ofJupiter. The ring which encircles the body ofthis planet, is inclined to the plane of the eclip-tic in an angle of about thirty degrees, in con-sequence of which its apparent figure is conti-nually varying. When the line of its nodespoints directly towards the earth, the ring, pre-senting its edge to the observer, becomes invi-sible; and if the same line points directly to-wards the fun, the ring cannot be seen for wantof illumination. But in general its figure isthat of an oval, which is broader and narrower,according as the line of the nodes is furtherfrom or nearer to the above position.

This ring is like a large flat circle, surround-ing the body of the planet, without touching it;its distance from Saturn being nearly equal to its

breadth,