A. MATHEMATICS AND ASTRONOMY. 13 







utes the uppermost were more than two hundred thousand 

 miles above the solar surface. The velocity of ascent, one 

 hundred and sixty-six miles per second, was considerably 

 greater than any hitherto recorded. 



As the filaments rose they gradually faded away like a dis- 

 solving cloud, and in about twenty minutes only a few filmy 

 wisps, with some bright streamers, low down near the chro- 

 mosphere, remained to mark the place. The whole phenome- 

 non suggested most forcibly to Professor Young the idea of 

 an explosion under the great prominence, acting mainly up- 

 ward, but also in all directions outward, and then, after an in- 

 terval, followed by a corresponding inrush ; and ft is thought 

 possible that the mysterious coronal streamers, if they turn 

 out to be truly solar, may find their origin and explanation 

 in such events. In conclusion, Professor Young inquires 

 whether the fine aurora which succeeded in the evening was 

 the earth's response to this magnificent outburst of the sun, 

 and thinks the coincidence at least suggestive. 12 A, Octo- 

 ber 19, 488/ Boston Journal of Chemistry. 



REDISCOVERY OF THE PLANET ERATO. 



Professor Oppolzer, of Vienna, has, after a careful calcula- 

 tion- and examination, rediscovered the planet Erato, which 

 has been lost for over eight years, and has fixed its present 

 position so that it can be readily found by the more powerful 

 telescopes. There still remain, however, quite a number of 

 planets, such as Maja, which has not been seen for fifteen 

 years, and ten others which were seen only once, and the re- 

 discovery of which is hindered by the want of proper oppor- 

 tunities of observers and of suitable telescopes. 1 C, xl., 640. 



PERIOD OF THE SUN'S ROTATION SHOWN BY MAGNETIC 



OBSERVATIONS. 



Hornstein has lately presented a paper to the Vienna Acad- 

 emy, in which he endeavors to show that the variation of each 

 one of the three elements of terrestrial magnetism (namely, 

 declination, inclination, and horizontal intensity) occur in a 

 period of twenty-six and one third days. 



This periodic variation, as he thinks, is caused by the rota- 

 tion of the sun; and as the duration of the period, from the 

 mean of observations, consists of 26.33 days, we have what 



