MARS ASTEROIDS JUPITER SATURN URANUS. 101 



globe ; and flying round its primary every twenty-two hours, a rapid succession of phases 

 will be exhibited. But the rings are doubtless the chief glory of the Saturnian firma- 

 ment at night, constituting a very noble spectacle, varying in their appearance according 



to the position of the place of observation. 

 From the polar regions they will scarcely be 

 perceptible, but at thirty degrees from the 

 poles a segment of them will be seen emerging 

 above the horizon, increasing in altitude as 

 equatorial latitudes are gained. Supposing 

 them appendages of the earth, the sketch may 

 convey no inaccurate idea of their appearance, at about sixty degrees from the equator. 



Sir John Ross, when in a high 

 northern latitude, observed a striking 

 aurora bestriding the sky, which he 

 describes as answering to his concep- 

 tions of the aspect of Saturn's rings as 

 seen from his surface. Advancing to 

 the equator, they will span the heavo- t 

 like magnificent arches near the ze- 

 nith, with the shadow of the planet 

 resting upon them, the satellites 

 pursuing their respective courses at 

 different distances, and the stars 

 shining on each side of the luminous 

 zones, and in the interval between 

 them. 



URANUS. The orbit of this remote body, which is removed to about twice the distance 

 of that of Saturn from the sun, is the present boundary of the planetary system ; but that 

 this is its actual limit that exterior to it there are no orbs analogous to those that are 

 interior, in obedient revolution round our central luminary, we are not in circumstances to 

 affirm. Uranus may be seen with the naked eye by a practised observer in fine weather when 

 the moon is absent, and appears like a fixed star of the least visible magnitude, shining with 

 a pale blue light. It was observed three times by Flajnstead, once by Bradley, once by 

 Mayer, eleven times by Lemonnier, who registered it among the stars ; but Herschel dis- 

 covered its planetary character at Bath in 1781, and thus effected an achievement, no 

 parallel to which history before had chronicled. For some time previous, astronomers 

 had been aware of the motions of Jupiter and Saturn being subject to certain perturbations 

 which could not be explained ; and it had been conjectured that some planet might revolve 

 beyond the latter, which would account for them. The verification of this idea illustrates 

 the accuracy of astronomical observations. The planet is situated at a mean distance 

 from the sun of 1,800 millions of miles, and has a path of more than 10,000 millions to 

 traverse in revolution round him, accomplished in a period of eighty-four years. One circuit 

 therefore has not been performed since it was discovered to be a member of the solar 

 system. It moves over one degree of its orbit in eighty-five days, and is thus seven years 

 in passing one constellation of the zodiac. Uranus, apparently insignificant in the heavens, 

 is the third of the planets in magnitude, eighty times larger than the earth in volume, 

 having a diameter of 35,000 miles. Slowly as he appears to travel, it is a pace of sixteen 

 thousand miles an hour, six satellites attending his course. These revolve round him 

 nearly at right angles to the plane of his orbit, in a direction from east to west singular 

 anomalies, exceptions to the general laws of the system. All the other primary planets 



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