Are yet arrived at this so foreign world;
Though nothing half so rapid as their flight.”
And Mr. Addison observes, that this thought of Mr. Huygens is far from being extravagant, when we consider that the universe is the work of infinite power, prompted by infinite goodness, having an infinite space wherein to exert itself, so that our imaginations can set no bounds to it.
The magnitudes of the stars appear to be very different from one another; which difference may probably arise, partly from a diversity in their real magnitude, but chiefly, no doubt, from their different distances. Hence it is, that the fixed stars have been divided, for the sake of distinction, into six orders or classes. Those which appear largest, are considered as stars of the first magnitude; the next to them in lustre, stars of the second magnitude; and so on, through the different gradations, to the smallest that are visible to the naked eye, which are said to be of the sixth magnitude. This distribution having been made long before the invention of telescopes, the stars which cannot be seen without the assistance of these instruments, are distinguished by the name of telescopic stars. Bayer, besides accurately distinguishing the relative size and situation of each star, marked the stars in each constellation with the letters of the Greek and Roman alphabets, setting the first Greek letter to the first or principal star in each constellation, to the second in order; then, when the Greek alphabet was gone over, he passed to a, b, c, of the Roman, and so on. This useful method of noting and describing the stars has been adopted by all astronomers since the time of Bayer; and they have further enlarged it, by adding the ordinal numbers 1, 2, 3, &c., when any constellation contains more stars than can be marked by the two alphabets.
As it would be impossible to furnish names for all the fixed stars, and retain those names in the memory; it became necessary not only to ascertain their exact relative situations, but to invent some method by which the principal part of the stars which can be seen may be known, without having recourse to a separate name for each. Ancient astronomers formed a commodious plan of arranging the fixed stars in constellations under names and figures of various personages, celebrated in antiquity, and even of birds, beasts, fishes, &c. This division of the heavens into constellations is obviously very ancient; for some of them are mentioned by Hesiod and Homer, both of whom probably flourished nearly 1000 years before the Christian era. Arcturus, Orion, and the Pleiades, are twice mentioned in the book of Job: and in the prophecy of Amos, composed about 400 years before Christ, the seven stars and Orion are mentioned. As the knowledge of the stars became more extensive, the number of the constellations was increased; and at the same time more stars were introduced into each constellation. Such of the stars as were not comprehended under any constellations, were by the ancient astronomers, called unformed stars. The modern astronomers have reduced not these unformed stars only, but many other stars, into new figures; and it is probable that other constellations will still continue to be invented.[137]
With respect to the number of fixed stars, there have been several accounts, given by different persons, at various times. The celebrated Hipparchus, of Rhodes, 120 years before Christ, formed a catalogue of 1,022 stars; to which Ptolemy added four more. Ulug Beigh, the grandson of Tamerlane, formed a catalogue of 1,017 stars. Tycho Brahé’s catalogue only extended to 777; but he took care to ascertain all their places. Kepler’s catalogue amounted to 1,163, which Ricciolus enlarged to 1,468. Bayerus extended his catalogue further than any of his predecessors, having described the places of 1,725. Hevelius increased the catalogue to 1,888. Flamsteed enlarged these catalogues to the number of about 3,000. But by means of the telescope, which affords us a glimpse of infinite space, and presents to our view myriads of worlds, and systems of worlds, by which it is filled, the number of the stars is astonishingly increased. Galileo found eighty stars in the space of the belt of Orion’s sword, and F. de Rheita observed more than 2,000 in the whole constellation of Orion, of which not more than seventy or eighty can ever be seen without glasses. Dr. Hook reckoned seventy-eight stars in the single constellation of the Pleiades; and F. de Rheita, with a better telescope, discovered 188: whereas we cannot reckon above seven or eight seen by the naked eye. At the present period, the positions of 60,000 fixed stars have been exactly recorded, and they are generally arranged according to the size they appear; 20 of the largest are called stars of the first magnitude; 65 are of the second magnitude; 205 of the third; 485 of the fourth; 648 of the fifth; and about 1,500 of the sixth magnitude; the remainder, being invisible to the naked eye, are called telescopic stars.
Where the stars are in great abundance, Dr. Herschell supposes they form primaries and secondaries, that is, suns revolving about suns, as planets revolve about the sun in our system. He considers that this must be the case in what is called the milky way, the stars being there in prodigious quantity. Of this he gives the following proof: on August 22, 1792, he found that in forty-one minutes of time, not less than 258,000 stars had passed through the field of view in his telescope! Dr. Chalmers observes, If we ask the number of suns and of systems—the unassisted eye of man can take in a thousand, and the best telescope which the genius of man has constructed can take in eighty millions. Thus, by the help of telescopes, we discover a vast multitude of stars which are invisible to the naked eye; and the better the glasses are, still the more become visible; so that we can set no limits either to their number, or to their distances.
“Myriads beyond with blended rays inflame
The milky way, whose stream of vivid light,
Poured from innumerable fountains round,