THE STARS CHAPTER I REVIEW OF RECENT PROGRESS These are thy glorious works, Parent of good, Thus wondrous fair.-MILTON. WE begin our study of the stars by a glance at the structure of the universe. What are familiarly known as the heavenly bodies belong to two classes which are very different as regards their relation to our earth. Those nearest to us form a sort of colony far removed from all the others, called the solar system. The principal bodies of this system are the Isun and eight great planets, with their moons, revolving round it. On one of these planets, small when compared with the great bodies of the universe, but large to our every-day conceptions, we dwell. The other planets appear to us as stars. Four of them, Venus, Mars, Jupiter, and Saturn, are distinguished from the fixed stars by their superior brightness and characteristic motions. Of the remaining three, Mercury will rarely excite notice, while Uranus is nearly invisible to the naked eye, and Neptune quite so. The dimensions of the solar system are vast when compared with any terrestrial standard. A cannonshot going incessantly at its usual speed would be five hundred years in crossing the orbit of Neptune from side to side. But vast as these dimensions are, they sink into insignificance when compared with the distances of the stars. Outside the solar system are spaces which, so far as we know, are absolutely void, save here and there a comet or a meteor, until we look far outside the region which a cannon-shot would cross in a million of years. The nearest star is thousands of times farther away than the most distant planet. Scattered at these inconceivable distances are the bodies to which our attention is directed in the present work. If we are asked what they are, we may reply that the stars are suns. But we might equally well say that the sun is one of the stars; a small star, indeed, surrounded by countless others, many of which are much larger and brighter than itself. We shall treat our theme as far as possible by what we may call the natural method, beginning with what, being most obvious to the eye, was first noticed by man, or will be first noticed by an observer, and tracing knowledge up step by step to its present state. Several features of the universe of stars will be evident at a glance. One of these is the diversity of the apparent brightness, or, in technical language, of the magnitudes of the stars. A few far outshine the great mass of their companions. A greater number are of what we may call medium brightness; there is a yet larger number of fainter ones, and about one-half of all those seen by a keen eye under favourable conditions are so near the limit of visibility as to escape ordinary notice. Moreover, those which we see are but an insignificant fraction of the number revealed by the telescope. The more we increase our optical power, the greater the number that come into view. How many millions may exist in the heavens it is scarcely possible even to guess. The photographic maps of the heavens now being made probably show more than fifty millions, perhaps one hundred millions, possibly twice this number. Another evident feature is the tendency of the brighter stars to cluster into groups, known as constellations. The latter are extremely irregular, so that we cannot always decide where one constellation should end and another begin, or to which constellation a certain star may belong. Hence, the definition and mapping out of the constellations and the division of the stars among them are somewhat arbitrary proceedings. A third feature is the Milky Way or Galaxy, which to ordinary vision appears as an irregular succession of cloud-like forms spanning the heavens. We now know that these seeming clouds are really congeries of stars too faint to be individually visible to the naked eye. We shall hereafter see that the stars of the Galaxy form, so to speak, the base on which the universe appears to be constructed. Each of these three features will be considered in its proper place. In the present chapter we shall make a rapid survey of what has been done in our time to advance our knowledge of the stars. A natural result of the northern hemisphere being the home of civilised peoples was that, until recent times, the study of the southern heavens had been comparatively neglected. It is true that the curiosity of the enquiring astronomers of the past would not be satisfied without their knowing something of what was to be seen south of the equator. Various enterprises and establishments had therefore contributed to our knowledge of the region in question. As far back as 1677, during a voyage to St. Helena, Halley catalogued the brighter stars in the region near the South Pole. About 1750 Lacaille, of France, established an observing station at the Cape of Good Hope, and made a catalogue of several thousand stars, which has remained a handy-book for the astronomer up to the present time. In 1834-38 Sir John Herschel made a special voyage to the Cape of Good Hope, armed with the best telescopes which his father had shown him. how to construct, for the purpose of doing for the southern heavens as much as possible of what his father had done for the northern. The work of this expedition forms one of the most important and interesting chapters in the history of astronomic science. Not only is Herschel's magnificent volume a classic of astronomy, but the observations which it contains are still as carefully and profitably studied as any that have since been made. They may be said to form the basis of our present knowledge of the region which they included in their scope. Herschel's work may be described as principally in the nature of an exploration. He had no instruments for accurately determining the positions of stars. In the latter field the first important contributions after Lacaille were made by Sir Thomas Brisbane, Governor of New South Wales, and Rumker, his assistant, at Paramatta. Johnson, of England, about 1830, introduced modern accuracy into the construction of a rather limited catalogue of stars which he observed at St. Helena. About the same time the British Government established the observatory at the Cape of Good Hope, which has maintained its activity to the present time. About the middle of the century the Government of New South Wales established, first at Williamstown and then at Melbourne, an observatory which has worked in the same field with marked success. The An American enterprise in the same direction was that of Captain James M. Gilliss, who, in 1849, organised an astronomical expedition to Chili. principal motive of this enterprise was the determination of the solar parallax by observations upon Venus and Mars about the time of their nearest approach to the earth. As these observations would take but a small part of his time, Gilliss determined to take with him instruments for determining the positions of the stars. He established his observatory at a point near Santiago, where he continued his observations for nearly three years. He was an excellent practical observer, but an untoward circumstance detracted |