Jupiter, who is attended (as I faid) with four, as we, who are nearer the Sun, are with one. Concerning which, these four things are remarkable.

1. Their Bulk, which in all probability is not in any of them less than our Earth, as the most ingenious Mr. Huygens concludes (2) from their fhade upon Jupiter's disk. By which means partly it is that

2. They reflect fo ftrong, brisk and vivid a light, as appears very illuftrious and entertaining even to us at fo great a diftance from it: which cannot but be very pleafing and comfortable to that Planet: befides the no less beneficial and friendly Influences therewith conveyed at the fame time.

(2) Cofmotheor. p. 101.

3. Their

3. Their due Distances from Jupiter, and from one another; and their agreeable periodick Revolutions which I have formerly observed (3) to be in the moft exact mathematical proportions. By the first of these, thole Satellites efcape all disagreeable Concourses and violent Oppofitions, and, in the moft kindly manner, fend their Influx to the Planet they wait upon and by the latter, they are perpetually carrying about their Light and other benefits from place to place. For by the motion of the Innermoft round once in less thantwo days; of the next in about 3 days; of the Third in fomewhat above a week; and of the Outermoft in near 17 days: by these means, I fay, it happens very feldom that any part of Jupiter is at any time without the prefence and at

(3) Book 4. Chap. 4.

ten

J

tendance of one or more of those Sa-
tellites; but one is vificing one part,
whilst another is attending another,
and another another part, and Jupi-
ter himself making speedy Returns
and Revolutions all the while.

4. The laft thing remarkable is
the Latitudes of Jupiter's Moons, or
their progreffes to his Poles, which
are in a due proportion to their Di-
ftances and Periods. The diligent
and ingenious Caffini hath determined
(4) the greateft Latitude of the In-
nermoft not to exceed a 3d part of Ju-
piter's Semidiameter; that of the next
about a quarter of his Diameter; that
of the Third about three quarters of
his Diameter (but I have my self ob
ferved it to be very nearly or alto-
gether parallel with Jupiter's Poles)

(4) Caffini's Les Hypoth. & Tab. des Sat. de Jupit. Sect. 4. among the Tracts of the Meffieurs del Acad. Roy. des Sciences.

and

and that of the Fourth or Outermoft to go beyond the Poles of Jupiter a third part of his Semidiameter. By· which means this Satellite efcapes the Ecliples of Jupiter's fhadow for the space of two years.

AND as the Latitudes of these Sátellites differ according to their Diftances and Periods; so another remarkable thing therein, is, that they fhift their Latitudes in longer or Thorter times,agreeable to their greater or leffer Latitudes; fome making their progreffes towards Jupiter's Poles one way, whilst some are wandering the other way,and some staying there à longer time, and fome a leffer and leffer time. By which quadruple vatiety of Latitudes, and perpetual changes of it, it comes to pass, that thofe large tracts towards the Polar parts of that vaft Planet, have their Thare in the light and kindly fervices

of

of the four Moons, and are leldom or never deprived of them.

Of Saturn's Moons, Ring, Days and Seafons.

H

AVING feen the admirable provifion made for the remedying Jupiter's great distance from the Sun; let us in the last place take a view of Saturn, which is above 200 millions of English miles farther from the Sun than Jupiter, and near 700 millions of miles father than is our Earth. And here our Glaffes, as imperfect as they are, have difcovered fo surprizing an Apparatus, that muft needs ftrike every one that views it with wonder and amazement.

Fo