PLATE I.]

79. He is surrounded by a thin broad Ring, as an artificial Globe is by

its Horizon. This Ring appears double when seen through a good

telescope, and is represented by the figure in such an oblique view as

it is generally seen. It is inclined 30 degrees to the Ecliptic, and is

about 21 thousand miles in breadth; which is equal to it’s distance from

Saturn on all sides. There is reason to believe that the Ring turns

round it’s Axis, because, when it is almost edge-wise to us, it appears

somewhat thicker on one side of the Planet than on the other; and the

thickest edge has been seen on different sides at different times. But

Saturn having no visible spots on his body, whereby to determine the

time of his turning round his Axis, the length of his days and nights,

and the position of his Axis, are unknown to us.

[Sidenote: His five Moons.

Astronomy Explained Upon Sir Isaac Newton's Principles And made easy to those who have not studied mathematics · 第 67 / 275 题