objects. Plate IV. gives a very beautiful view of a number of them as seen by Trouvelot with the great telescope at Cambridge, U.S. These drawings show the red colour of the flame-like objects, not very happily described as prominences; and they also show, in the different pictures, the wondrous variety of aspect which these objects assume. The dimensions of the prominences may be inferred from the scale appended to the plate. The largest of them is fully 80,000 miles high; but many observers have recorded prominences of much greater altitude. The rapid changes of these objects is well illustrated in the two sketches on the left of the lowest line, which were drawn on April 27th, 1872. These are both drawings of the same prominence taken at an interval no greater than twenty minutes. This mighty flame is so vast that its length is ten times as great as the diameter of the earth, yet in this brief period it has completely changed its aspect; the upper part of the flame has, indeed, broken away, and is now shown in that part of the drawing between the two figures on the line above. The drawings also show various instances of the remarkable spike-like prominences, taken at different times and on different parts of the sun. These spikes usually attain altitudes not greater than 20,000 miles, but sometimes they stretch up to stupendous distances. We may quote one special object of this kind, whose remarkable history has been chronicled by Professor Young, the well-known authority in this department of astronomy. On October 7th, 1880, a prominence was seen, at about 10:30 a.m., on the south-east limb of the sun. then an object of no unusual appearance, being about 40,000 miles high, and attracted no special attention; but half an hour witnessed a marvellous transformation. During that brief interval the prominence became very brilliant, and doubled its length. For another hour the mighty flame still soared upwards, until it attained the unprecedented elevation of 350,000 miles-a distance more than one-third of the diameter of the sun. Here the energy It was During a visit to the United States in the autumn of 1884, the author was fortunate enough, by the kindness of Professor Young, to observe several solar prominences with the superb instruments at Princeton, New Jersey. of the mighty outbreak seems to have expended itself: the flame broke up into filaments, and by 12.30-an interval of only two hours from the time when it was first noticed-the huge prominence had completely faded away. The facts we have recorded give a surprising indication of the violence of those fiery storms by which the surface of the sun is occasionally disturbed. No doubt this vast prominence was exceptional in its magnitude, and in the vastness of the changes of which it was an indication; but we may, at all events, take it as the basis of an estimate of the maximum changes which the surface of the sun witnesses. The velocity must have been 200,000 miles an hour-a rate which must have more than averaged fifty miles a second. This mighty flame leaped up from the sun with a velocity more than 100 times as great as that of the swiftest bullet that was ever fired from a rifle. The most striking feature of a total eclipse of the sun is unquestionably the Corona, or aureole of light which is then seen to surround the sun. On such an occasion, when the sky is clear, the moon appears of an inky darkness, not like a flat screen, but like the huge black ball that it really is. "From behind it (I quote Professor Young) stream out on all sides radiant filaments, beams, and sheets of pearly light, which reach to a distance sometimes of several degrees from the solar surface, forming an irregular stellate halo with the black globe of the moon in its apparent centre. The portion nearest the sun is of dazzling brightness, but still less brilliant than the prominences which blaze through it like carbuncles. Generally this inner corona has a pretty uniform height, forming a ring three or four minutes of arc in width, separated by a somewhat definite outline from the outer corona, which reaches to a much greater distance, and is far more irregular in form; usually there are several "rifts," as they have been called, like narrow beams of darkness, extending from the very edge of the sun to the outer night, and much resembling the cloud shadows which radiate from the sun before a thunder shower. But the edges of these rifts are frequently curved, showing them to be something else than real shadows; sometimes there are narrow bright streamers |