The Earth is attended by the _Moon_, who performs her revolution in about 27⅓ Days, at the distance of about 30 Diameters of the Earth from it; and once a Year is carried round the Sun along with the Earth. [Sidenote: _Jupiter’s_ four Moons.] _Jupiter_ has four _Moons_, or _Satellites_; the _first_, or innermost, performs its revolution in about one Day, and 18½ Hours, at the distance of 5⅔ Semidiameters of _Jupiter_, from his Center; the _second_ revolves about _Jupiter_ in 3 Days, 13 Hours, at the distance of 9 of his Semidiameters; the _third_ in 7 Days, and 4 Hours, at the distance of 14⅓ Semidiameters; the _fourth_, and _outermost_, performs its course in the space of 16 Days, 17 Hours; and is distant from _Jupiter’s_ center, 25⅓ of his Semidiameters. [Sidenote: _Saturn_ has five Moons.] _Saturn_ has no less than five _Satellites_; the _first_, or innermost, revolves about him in 1 Day, and 21 Hours, at the distance of 4⅜ Semidiameters of ♄, from his center; the _second_ compleats his period in 2¾ Days, at the distance of 5³/₅ of his Semidiameters; the _third_, in about 4½ Days, at the distance of 8 Semidiameters; the _fourth_ performs its course in about 16 Days, at the distance of 18 Semidiameters; the _fifth_, and outermost, takes 79⅓ Days, to finish his course, and is 54 Semidiameters of _Saturn_ distant from his center. The Satellites, as well as their primaries, perform their revolutions from _West_ to _East_: The planes of the Orbits of the Satellites of the same Planet are variously inclined to one another, and consequently are inclined to the plane of the Orbit of their primary. [Sidenote: _Saturn’s_ Ring.] Besides these attendants, _Saturn_ is encompassed with a thin plain Ring, that does no where touch his body; The diameter of this Ring is to the diameter of _Saturn_, as 9 to 4; and the void space between the Ring and the body of _Saturn_ is equal to the breadth of the Ring itself; so that in some situations the Heavens may be seen between the Ring and his body. This surprizing phænomenon of _Saturn_’s Ring, is a modern discovery; neither were the Satellites of _Jupiter_ and _Saturn_ known to the ancients. The _Jovial_ Planets were first discovered by the famous _Italian_ philosopher _Galilæus_, by a telescope which he first invented; and the celebrated _Cassini_, the _French_ king’s astronomer, was the first that saw all the Satellites of _Saturn_; which by reason of their great distances from the Sun, and the smallness of their own bodies, cannot be seen by us, but by the help of very good glasses. [Sidenote: _Annual Motion._] [Sidenote: _Diurnal Motion._]