represented many of the events which they have recorded in a very different and, perchance, less contenting manner. Naturally, in the ages in which bards, scalds, or minstrels-by whichever name one chooses to call them-were the only preservers of the records of the time, truth was constantly blended with the most extravagant fictions and exaggerations; and though most of these fictions, with the incidents which they embellished, have perished or become difficult of access, Yet fragments of the lofty strain And these fragments, whatever their defects, both ethical and metrical, are interesting, as they most of them commemorate events which have affected, at one time or another, in a greater or less degree, almost all the nations of the earth; and they are both interesting and valuable as faithfully representing the kind of literary, historical, and ethical pabulum on which were nourished the men who have contributed some lively pages to the world's history. FRED. S. LEFTWICH. THE THE SUNS OF SPACE. HE fact that the stars are suns like our own sun has long been known to astronomers. So far back as 1750, Thomas Wright, of Durham, in his work on the "Construction of the Milky Way," said: "The sun is a star, and the stars are suns;" and the poet Young, in his "Night Thoughts," says: One sun by day, by night ten thousand shine. The truth of this theory, which must have always seemed a most probable one to a thinking mind, has been fully proved in recent years by the spectroscope, which shows that the stars are incandescent bodies shining by their own light, and that many of them are almost identical in physical constitution with our own sun. All the stars, however, do not show exactly the same character of spectrum, and they have therefore been divided into classes or types according to the nature of the light which they emit. Stars of the first type, like Sirius, Vega, Regulus, Altair, &c., show a spectrum with strong dark lines of hydrogen, and are believed by astronomers to be intrinsically hotter and brighter than stars with a solar type of spectrum, which constitute the second type of stellar spectra. The third and fourth types are essentially different from the other two, and include the red stars, many of which are variable in light. Although all the types probably represent suns of various kinds and in various stages of their life history, those of the second type only are strictly comparable with our sun in their physical constitution. But how are we to compare the sun with any star? The first thing necessary to know is, of course, the distance of the star from the earth, for without this knowledge the star might be of any size. It might be comparatively near the earth and of small diameter compared with the sun, or it might be at a great distance and have an enormous diameter. The next thing to ascertain is the relative brightness of the star compared with that of the sun. This is also most important, for the apparent brightness of any self-luminous sphere varies directly as the square of its diameter, so that if we can find the relative brightness of the sun and a star, י we can find their relative diameters if their relative distances are known, provided that their intrinsic brilliancy of surface is the same. This latter condition we may assume to be practically true, if the star's spectrum is similar to that of the sun. These two factors of distance and relative brightness being known it becomes possible to compare directly the diameter of the sun (and hence its volume). with that of a star having the same type of spectrum. Now it has been computed that the brightness of the sun may be represented by stating that it is twenty-seven magnitudes above the zero of stellar magnitudes, or twenty-eight magnitudes brighter than an average star of the first magnitude, such as Aldebaran. The meaning of "stellar magnitude" is that a star of the first magnitude is 2.512 times as bright as a star of the second magnitude; a star of the second magnitude 2'512 times as bright as one of the third, and so on. Or, generally, if n be the difference in magnitude, then (2'512)" will represent the difference in brightness. Hence the sun will be (2512)28 times brighter than an average star of the first magnitude; that is, the sun is equal in brightness to 158,500 million stars of the first magnitude. In the following paper I will consider those stars of which the distance has been determined with some approach to accuracy, and of which the spectrum-according to the "Draper Catalogue of Stellar Spectra," observed at Harvard—is of the solar type (F), and therefore fairly comparable with that of the sun. The first star I will consider is Beta Cassiopeiæ, one of the stars forming the well-known "Chair of Cassiopeia." For this star the late Professor Pritchard found, by means of photography, a parallax of 0.154 of a second of arc, which would place it at a distance of 1,339,380 times the sun's distance from the earth. Were the sun placed at this vast distance-about twenty-one years' journey for light-I find that its light would be reduced to that of a star of magnitude 3.63 (light varying inversely as the square of the distance). Now the photometric magnitude of Beta Cassiopeia, as measured at Harvard Observatory, is 2:42. Hence the star is 121 magnitude, or about three times brighter than the sun would be at the same distance. Hence, if strictly comparable with the sun in physical constitution, the diameter of Beta Cassiopeia would be 1 times that of the sun, and its mass about 5 times the mass of the sun. Eta Cassiopeia. A parallax of 0.465 of a second has recently been found for this star by means of photography. This would give a distance of 443,600 times the sun's distance from the earth. The sun placed at this distance would shine as a star of 113 magnitude, 1 See my paper in Knowledge for June 1895. and as the photometric magnitude of Eta Cassiopeia is 364, it would follow that the sun is ten times brighter than the star, and hence the mass of the star would be only 3 of the sun's mass. The star is a well-known binary, or revolving double star; and an orbit recently computed by Dr. See, combined with the above parallax, gives for the mass of the system 4th of the sun's mass. The discrepancy between the above results may be partly explained by the fact that the comparison, which, of course, has a mass of its own, is faint, and does not perceptibly influence the light of the primary star. For the Pole Star, a parallax of o'015 of a second has been found by De Ball. Placed at the distance indicated by this minute parallax, the sun would be reduced to a star of only 8.69 magnitude, and as the photometric magnitude of the Pole Star is 2'15, we have a difference of 6.54 magnitudes in favour of the star. This would make the star 413 times the brightness of the sun, and its mass no less than 8,395 times the sun's mass! This is a rather startling result, but the small value of the parallax of course makes its accuracy somewhat doubtful. Brioschi found a parallax of o'60 of a second, which would considerably reduce the mass; but most of the results found in recent years have been very small. It would therefore seem that the Pole Star is probably a sun of enormous size. The spectrum is a doubtful one (F?) of the solar type. For the brilliant star Capella a parallax of 0.107 of a second was found by Dr. Elkin. This would give a distance of 1,927,700 times the sun's distance from the earth, and at this distance the sun would be reduced to a star of 4'42 magnitude. As the photometric magnitude of Capella is o'18, it follows that the star is 4:24 magnitudes, or 49'66 times brighter than the sun. This would make its diameter about seven times the sun's diameter, and its mass about 350 times the mass of the sun. A considerably larger parallax of o'522 of a second was, however, found by Glasenapp, which would make the sun but little inferior to the star in brightness and mass. The star's spectrum is very similar to the solar spectrum. Procyon. For this brilliant star Auwers found a parallax of 0'240 of a second, Wagner o""229, and Elkin o266. Elkin's value, which is about a mean of the other two, would place the star at a distance of 775,430 times the sun's distance from the earth. This would reduce the sun's brightness to a star of magnitude 2:45; and as the photometric magnitude of Procyon is o'46, it follows that the star is 6 times brighter than the sun. This would make its diameter 2 times that of the sun, and its mass about 15 times the sun's mass. Its spectrum is of the same type as the sun and Capella, and its brilliancy would lead us to believe that it is a sun of large size. Theta Ursa Majoris. This is another star with a spectrum of the solar type. A small parallax of 0·046 of a second was found by Kapteyn. Placed at the distance indicated by this parallax the sun would shine as a star of 6·26 magnitude. But the star's photometric magnitude being 322, it follows that the star is 3'04 magnitudes, or 16:44 times brighter than the sun. Its mass would therefore be about 66 times the mass of the sun, so that if the parallax is at all reliable we have here another sun of large size. 85 Pegasi. For this star Brünnow found a small parallax of 0'054 of a second. The sun if placed at the distance indicated by this parallax would shine as a star of 5'91 magnitude, and as the star's photometric magnitude is 5·83, we have the sun and star almost exactly equal in brightness, and therefore probably nearly equal in mass. The star is a binary, and from an orbit recently computed by Dr. See and the above parallax, I find that the mass of the system would be nearly eight times the mass of the sun. The star's spectrum (E) is, however, not exactly the same as that of the sun, and the star may therefore not be strictly comparable with the sun in brightness. If we assume that the intrinsic brilliancy of its surface is somewhat less than that of the sun, then its diameter, and therefore its mass, may be greater than our sun's. Although stars with spectra of the Sirian type are not directly comparable with the sun in brightness, being probably much hotter, it will be interesting to consider some of the stars having this type of spectrum. In the case of Sirius itself, I find that the sun placed at the distance indicated by a parallax of o'37 of a second, found by Dr. Gill, would shine as a star of 1.73 magnitude, and as the photometric magnitude of Sirius-as measured at Harvard-is +143, or 1'43 magnitudes brighter than the zero of stellar magnitudes, it follows that the star is 3.16 magnitudes, or 18:37 times, brighter than the sun. Dr. See finds from his orbit that the combined mass of Sirius and its companion is 3'473 times the mass of the sun, the mass of the primary star being 2:36, and that of the companion-which is faint-1113. From this it follows that if Sirius had the same density and intrinsic brightness of surface as the sun it would be only 1773 times brighter. Hence its brightness is over ten times greater than it would be if its physical constitution were the same as that of It would seem therefore that the great apparent brightness of Sirius is due to its comparative proximity to the earth, combined |