28 ASTRONOMICAL PHENOMENA. 



AURORA BOREALIS. 



which the medal was chiefly awarded may be 

 considered as an extension of Argelander's 

 scale of magnitudes to all the stars which can 

 be seen by a good eye, without instrumental 

 aid, between 10 north declination and the 

 south pole, together with a series of charts ex- 

 hibiting, on a stereographic projection, the 

 positions of all these stars to the sixth magni- 

 tude, and a proposed revision of the boundaries 

 of the southern constellations." 



On presenting the medal, the president of 

 the society, E. J. Stone, F. R. S., delivered an 

 address in which the labors of Dr. Gould were 

 briefly reviewed, and concluding as follows: 

 " The ' Uranoraetria Argentina ' is a work of 

 very considerable extent ; it has been planned 

 with great care, and executed with the most 

 scrupulous attention to details. It will remain 

 an enduring record of the relative brightness 

 of the southern stars for its epoch ; and will be 

 accepted for many years as the chief authority 

 upon questions of their magnitude." 



The "Comptes Rendus," vol. xcvi, No. 14, 

 announced that the French Academy of Sci- 

 ences had awarded the Lalande prize to M. 

 Souillart, Professor in the Faculty of Sciences 

 in Lille, for his investigations into the theory 

 of Jupiter's satellites. A prize of 2,000 francs 

 was given to Dr. W. Schur for his determina- 

 tion of the mass of Jupiter, and of the eccen- 

 tricities of the orbits of the first and second 

 satellites. The first Valz prize was awarded 

 to Dr. Huggins, of England, chiefly for his 

 spectroscopic determination of the motions of 

 stars in the line of sight. The stcond Valz 

 prize was given to M. Cruls, director of the 

 observatory at Rio Janeiro. 



Llek Observatory. The dome for the 12-inch 

 equatorial telescope of the Lick Observatory, 

 as well as buildings for the transit and the 

 photo- heliograph, was finished some months 

 since. The instruments have been mounted, 

 and are said to be in excellent working order. 

 The walls of the main building are approach- 

 ing completion, and arrangements are in prog- 

 ress for the reception of the great 36-inch 

 equatorial. The house for the meridian circle 

 has been begun, and a residence for the direct- 

 or and his assistants will be provided as soon 

 as practicable. 



Potsdam Obsmatory. Prof. H. C. Vogel, 

 Director of the Astrophysical Observatory of 

 Potsdam, has undertaken the preparation of a 

 complete spectroscopic star-catalogue. The 

 examination of the zone extending from 1 

 south declination to 20 north has been com- 

 pleted, and the second zone, from 20 to 40 

 north declination, will soon follow. " To pre- 

 pare such a catalogue," says Vogel, "is a duty 

 which the present generation owes to posterity. 

 The changes taking place in the stars are of 

 special interest to us, and are of importance to 

 science ; and although it may be conjectured 

 that changes in the spectra will show them- 

 selves soonest in those stars which have pro- 

 ceeded further in their development, that is, 



in the red stars, yet this can not be positively 

 affirmed a priori. Equally with those wonder- 

 ful spectra of the red stars, which so enchant 

 the eye of the observer, will changes take 

 place in the course of time in the simple spec- 

 tra of the white and yellow stars, so that 

 investigations of as large a number of star- 

 spectra as possible, without limiting them to 

 particular classes of stars, are absolutely ne- 

 cessary for future researches." 



The Annual Report of the Council of the 

 Royal Astronomical Society of London, read 

 February 9, 1883, contains an account of the 

 proceedings of the British observatories, public 

 and private, for the past year. Most of the 

 results, however, have been already given. At 

 the Royal Observatory, Greenwich, arrange- 

 ments have been made with the committee on 

 solar physics by which the gaps in the Green- 

 wich series of sun-pictures may be filled up by 

 photographs taken in India, thus rendering 

 the series almost perfectly continuous. The 

 Oxford University Observatory has been chief- 

 ly directed to the photometry of the brighter 

 stars of the northern hemisphere. At Mr. 

 Huggins's observatory, Upper Tulse Hill, the 

 director has obtained photographs of the sun's 

 corona without an eclipse. "In the longer 

 exposed plates," Dr. Huggins remarks, "the 

 outer corona with its rays of varying length 

 and peculiar rifts is seen ; in the plates with a 

 shorter exposure the inner corona, which is 

 more nearly uniform in height, may be seen 

 under suitable illumination. The average 

 heights of the outer and inner coronse agree 

 closely with the coronse as seen on the plates 

 taken in Egypt," during the total eclipse of 

 May 16, 1882. 



AURORA BOREALIS. The phenomena of the 

 aurora borealis have recently been made the 

 object of several special studies. They have 

 long been regarded as of electrical origin, but 

 nothing was known of the source of the elec- 

 tric currents that produced them, or of the 

 manner of action under which the different 

 kinds of auroral phenomena were manifested. 

 M. de la Rive, a physicist of Geneva, set forth 

 the hypothesis, about 1850, that the earth is 

 charged with positive, and the upper strata of 

 the atmosphere with negative electricity, and 

 that two currents, very strong in the tropical 

 regions, are constantly proceeding toward the 

 polar regions, where they meet through the 

 medium of an air containing infinitesimal vesi- 

 cles of water and crystals of snow and ice, and 

 consequently having higher conducting pow- 

 ers. He constructed an apparatus by the aid 

 of which, establishing conditions similar to 

 those he regarded as fundamental to his the- 

 ory, he produced, on a minute scale, luminous 

 phenomena comparable in appearance to those 

 of the aurora. 



Mr. Nordenskjold, the Swedish explorer, 

 when wintering near Bering Strait, in 1878, 

 observed on perfectly favorable nights a faint 

 luminous arc having its culminating point in 



