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'the morning or evening sky, and at other times her 

 disc is comparatively inconspicuous. Both these 

 planets, being " inferior," or nearer the sun than the 

 earth, juresent phases similar to those of the moon. 

 Beyond this there is not much to be made out on 

 either. 



We now come to planets not known to the ancients. 

 William, afterwards Sir William, Herschel, who 

 in later years became so celebrated for his large 

 telescopes and the work that he accomplished, 

 noticed in 1 781 a peculiar object that he at first 

 imagined was a comet. It was however soon found 

 to be another planet, to which the name of Uranus 

 was afterwards given, and the solar system was by 

 this discovery at once extended to a distance of 

 1,780,000,000 miles. In more recent years four 

 moons have been observed to accompany him. His 

 distance from us is so great that, although his diameter 

 is 30,000 miles, not much can be seen on the surface 

 even with the largest telescopes. The same remark 

 applies, but in a greater degree, to that which is, as 

 far as our knowledge extends at present, the most 

 distant planetary member of our system — Neptune, 

 ■1,000,000,000 miles more remote from the sun than 

 Uranus, with a diameter of 37,000 miles. We know 

 very little about him and his solitary moon. It is 

 more than probable that we are not yet acquainted 

 with all the satellites of these distant planets. The 

 circumstances attending the discovery of Neptune are 

 most remarkable and most interesting. It can be 

 easily imagined that when astronomers are made aware 

 of the appearance of a heavenly body in a part of the 

 sky where it is known not to have been previously 

 visible, very little time is lost in endeavouring to find 

 out all that is possible respecting the stranger. Con- 

 sequently, when the body discovered by Herschel — not 

 by chance, be it remembered, but in the course of a 

 systematic series of observations — was found to be in 

 motion round the sun, mathematicians at once set to 

 work to find out its orbit, from which the place 

 occupied by it at any time either before, or after, its 

 discovery could be determined. This having been 

 done, it was found, though not till many years had 

 elapsed, that the planet was not pursuing the path 

 that theory had marked out for it. It was evidently 

 being attracted, or dragged out of its course, by some 

 as yet unknown body ; for, according to the conclu- 

 sion arrived at by Newton, every particle of matter in 

 the universe is attracted by every other particle in a 

 certain manner depending on their mass and their 

 distance. The question now to be answered was, 

 What and where is the body which is dragging 

 Uranus out of his course, and what is its mass ? In 

 the calculation of its orbit all the effects of this nature 

 which could be produced on it by planets nearer the 

 sun than itself had been taken into account. From a 

 certain apparent law of progression in the distances 

 of the known planets from their primary, it was 

 assumed that the unknown body must be much more 



remote than Uranus. The solution of the question 

 involved extreme difficulties ; these, however, were 

 surmounted almost simultaneously by two very able 

 mathematicians, each working quite independently — 

 Adams in England and Leverrier in France — and the 

 place of the stranger having been theoretically 

 determined, it was found in almost that identical spot 

 by the telescope. This discovery took place in 1846. 

 A noble triumph, truly, of mathematical skill and a 

 noteworthy instance of a dogged pursuit of knowledge 

 under great difficulties, worthy of all praise. 



Between the orbits of Mars and Jupiter it was long 

 noticed that there was an unaccountable gap. This 

 is now found to be occupied by a considerable number 

 of minor planets, about three hundred of which have 

 been discovered within the last ninety years. From 

 their very minute size they are not, telescopically, 

 objects of interest to the ordinary observer. 



As the eye-piece is merely a small microscope 

 employed to enlarge the image formed in the focus 

 of the object-glass or mirror, a number of these 

 appliances is always supplied with every telescope, 

 and the observer can select the one that best suits his 

 purpose. The deeper the eye-piece, the larger will 

 an object appear if it has a disc or occupies an 

 appreciable space. But the case is different when we 

 view the stars. For, though they are of enormous 

 size, they are at a still more enormous distance, and 

 with no increase of power can they be made in a 

 good telescope to appear much other than points. 

 Indeed, the better the instrument is, the smaller are 

 the star-discs. 



Having exhausted the list of planets, it will be 

 worth while to turn our attention to what are com- 

 monly known as fixed stars, so called, not because 

 they are immovable, but because they are not 

 wanderers or planets. Still relying on the better 

 knowledge of our friend, we shall probably be shown 

 first some of the stars in the more familiar constella- 

 tions ; and then others which, perhaps less con- 

 spicuous to the naked eye, are noteworthy for the 

 beauty of their colour, for some are white, others 

 red, yellow, blue, &c. Among the most beautiful of 

 these may be mentioned /3 Cygni, 7 Andromedae and 

 a Herculis. But we shall not find that all stars are 

 of the same degree of brightness, though this is not 

 necessarily an indication of either their size or their 

 distance. It has been found convenient to divide 

 them into classes or "magnitudes," the brightest 

 being considered of the first magnitude. Few 

 persons can, without optical aid, discern as separate 

 objects stars which are of less than the sixth magni- 

 tude, but the order is continued much further for 

 telescopic stars. The determination of magnitudes 

 has till recently been not much more than a matter 

 of estimation ; but, as science demands exactness, 

 means have been devised of late years, notably by 

 Professor Pritchard, of Oxford, to secure this end. 

 His mode of procedure is to view the star, the 



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