There is a singular and curious appendage to Saturn, namely, a thin, broad, opake ring, encompassing the body of the planet, without touching it; like the horizon of an artificial globe; it appears to be suspended round the planet, and to keep its place without any immediate connection with it. The distance of this prodigious circle from the body of the planet is usually stated to be about 21,000 miles.
The dimensions of the ring, or of the two rings with the space between them, Dr. Herschell has given as follows:
| Miles. | |
|---|---|
| Inner diameter of the smaller ring | 146,345 |
| Outside diameter of ditto | 184,393 |
| Inner diameter of the larger ring | 190,248 |
| Outside diameter of ditto | 204,883 |
| Breadth of the inner ring | 20,000 |
| Breadth of the outer ring | 7,200 |
| Breadth of the vacant space, or dark zone | 2,839 |
It puts on different appearances to us, sometimes being seen quite open, or as a wide oval, and at others, only as a single line. When our eye is in the plane of the ring, or looking at it directly on the edge, it is invisible to us; and it is in this situation twice in each revolution of the planet; that is, once in about fifteen years: at these times, he appears quite round, for nine or ten months together. The ring was invisible to us on the 15th of June, 1803, and, since that time, gradually increased in light and breadth for about seven years: and, after which, has again decreased, till, as before, after an interval of fifteen years, in the present year 1818, the ring is again edgewise to us, and invisible. With telescopes of great magnifying power, two belts or stripes have been discovered on Saturn; they appear parallel to the ring, and are supposed to be permanent. Of what component materials this ring is composed, or by what means it is suspended, we as yet remain ignorant: but of its use, it is supposed to supply light and heat to the planet, agreeably to the observation of a poet who has evinced an extensive acquaintance with philosophy.
“Muse! raise thy voice, mysterious truth to sing,
How o’er the copious orb a lucid ring,
Opake and broad, is seen its arch to spread,
Round the big globe at stated periods led;
Perhaps (its use unknown) with gather’d heat
To aid the regions of that gelid seat,