ASTRONOMICAL PROGRESS IN 1898. 



been chiefly employed in taking negatives of the 

 Moon for the Photographic Atlas of her surface 

 that is now being published. 



The first part of the task allotted to the observa- 

 tory in connection with the photographic construc- 

 tion of the great catalogue of stars is practically 

 completed. Of the 1,260 plak-s that fell to its 

 share, only a few remain to be takon, and these only 

 for some" which, from accidental causes, were 

 rejected during the progress of the work. The 

 rectilinear co-ordinates of the stars to the eleventh 

 magnitude have already been determined on 429 of 

 these plates. Attention is called to an admirable 

 heliograph of the crescent Moon when 4 d 6 h 24 m 

 old, which never has been surpassed. 



Photographic Spectra. After many unsuc- 

 cessful attempts to photograph the spectrum of the 

 aurora at the many observatories Mr. E. S. King 

 has succeeded. One plate shows four bright lines, 

 and another two bright lines. Assuming that the 

 lines on both occasions were the same, the four lines 

 have wave lengths 3862, 3922, 4288, and 4964. 



A photograph of the spectrum of shooting stars 

 was obtained at the Harvard College Branch Obser- 

 servatory, at Arequipa, Peru, on June 18, 1897. 

 The spectrum consists of six bright lines, the inten- 

 sity of which varies on different portions of the 

 photograph, thereby showing that the light of the 

 meteor varied as its image passed across the plate. 

 The approximate wave lengths of the lines are 3954, 

 4121, 4195, 4344, 4636, and 4857, and their inten- 

 sities are estimated as 40, 100. 2, 13, 10, and 10 

 respectively. The first, second, fourth, and sixth 

 of these lines are probably identical with the hy- 

 drogen lines He. 118, tty, H/3, whose wave lengths 

 are 3970, 4101, 4341, and 4862. The fifth line is 

 probably identical with the band at wave length 

 4633, belonging to the spectra of stars of the fifth 

 type, and forming the distinctive feature of the 

 third class of these stars. This is the first time a 

 spectrum has been obtained of a shooting star. 



Photogrnphy of Meteors. Meteor trains on 

 photographic plates are of frequent occurrence. Dr. 

 E. E. Barnard, of the Yerkes Observatory, at Wil- 

 liams Bay, Wisconsin, who is authority on celestial 

 photography, says: "For such work it is best to use 

 a short-focus portrait lens, or, where the scale is not 

 too important, a small cheap lantern lens is far 

 more rapid and gives a wider field. This is best 

 attached to an equatorial telescope with clock 

 motion, but good work can be done with a fixed 

 camera, and if two observers are situated several 

 miles apart their parallaxes and, of course, their 

 height in miles above the Earth may be easily 

 obtained." 



Star Showers. Before the volume in which 

 this article appears is published, the forerunner of 

 the great shower of 1899 will have occurred, and 

 before the volume of 1900 reaches its readers the 

 return of the great meteoric showers of 1799, 

 1833, and 1866 will also have taken place. It seems, 

 therefore, advisable to go somewhat into detail as to 

 its cause, and what may be expected on its return 

 in 1899. 



Prolonged investigation has revealed the fact that 

 shooting stars have their origin in disintegraied 

 i Minets. They are cold, dark bodies, but in en- 

 countering our atmosphere, moving as they do with 

 unimagined swiftness, they are instantly, by friction 

 with the atmosphere, converted into heat so intense 

 that they are instantly burned up. Only while 

 undergoing the process of combustion do they 

 become visible-. They are very small, probably not 

 larger than rice grains. Bol'ides and the fall of 

 meteoric stars have no connection whatever with 

 shooting stars, which never reach the Earth: the 

 atmosphere, acting as a cushion, prevents, especially 



during a star shower, a dangerous bombardment. 

 Many millions enter our atmosphere daily and are 

 dissipated into vapor. Each one is a remnant of 

 the tail of some comet. These are called sporadic 

 meteors, to distinguish them from those that fall in 

 showers, of which something like 100 are known, 50 

 of which have their radiants well established. 



The history of the Nov. 13th shower can bo 

 traced to A. D. 902 (0. S). At that time it occurred 

 in October. It is the greatest of them all, and 

 was historically noticed on the morning of Nov. 

 12, 1799, on the 13th in 1833, and on the 14th in 

 1866, and it will reappear on the morning of the 

 15th, 1899. The writer witnessed that of 1833, 

 when it was estimated that 230,000 shooting stars 

 were seen from any one point. The display was 

 visible throughout the length and breadth of the 

 American continent. It was immediately noticed 

 that, in whatever part of the sky they were seen, 

 their trails, if traced backward, would meet like 

 the radii of a circle, at the sickle of Leo, called the 

 radiant. The radiant of the 1899 shower will still 

 be there, or very near it. It is not a point, but an 

 eclipse about five degrees in diameter. 



The cause of this shower, briefly stated, is about 

 as follows : In A. p. 902 a large comet entered our 

 system, having a direct motion (west to east), and, 

 passing near the planet Uranus, had its orbit 

 changed to retrograde (east to west), and threw off 

 a long tail, which, after several reappearances and 

 repetitions, formed a ring of comet tails around 

 the sky, so situated that the Earth passes diagonally 

 through it about the middle of every November, 

 producing a light shower of meteors, which lasts as 

 long as the Earth is passing diagonally through it 

 and no longer, five or six hours. On one of its 

 returns, the comet, from some unknown cause, 

 burst, scattering its little particles, called meteor- 

 oids, along its path for many million rtiiles. These 

 meteoroids revolve around the Sun once in thirty- 

 three and a quarter years; and as this is not an 

 even multiple of the Earth's revolution, the Earth 

 passes annually through it in a new place, which 

 brings the swarm to the crossing point about three 

 times in a hundred years. The last took place in 

 1866, and the next will occur on the morning of 

 Nov. 15, 1899. It may possibly be on the 14th, 

 which was the case in 18G6, and as the swarm is 

 many million miles long, it is expected that the 

 Earth will pass through one end of it in 1898, and 

 through the other end in 1900. Neither the point 

 where, in the cluster, the Earth will pass through 

 nor which continent will be ahead, so to speak, 

 when the cluster is encountered, can be foretold. 

 It is expected that the middle shower (1899) will far 

 outshine the other two, but unfortunately it will 

 happen in the presence of a full Moon. The reader 

 may nsk why this shower always takes place in the 

 morning hours, while the Aug. l()th shower 

 always occurs in the evening hours! The meteoric 

 ring that causes the Nov. 15th display (not the 

 Nov. 27th shower) revolves around the Sun retro- 

 grade ; the Earth therefore overtakes it on the 

 front side, so to speak, or, in the morning hours. 

 while the ring that produces the Aug. l()th shower. 

 the Perseids, moving direct, overtakes the Earth on 

 the rear or evening side. 



Prof. Theodor Bredikhine has given, in the "Eul- 

 letin of the St. Petersburg Academy," the results of 

 his investigations as to what members of the solar 

 system are responsible for the disturbances in those 

 meteoric systems encountered by the Earth In its 

 annual orbit. He adopts the view that meteoric 

 systems are composed of the fragments of comets 

 which, traveling the interplanetary spaces, have lost 

 a portion of their material. The larger number of 

 meteoric streams examined have resulted from long 



