ASTRONOMY, PROGRESS OF, IN 1802. 



35 



tudc from 17 S. to SO" S. It was not seen at the 



sixth rotation of the sun upon its axis. 



The diminution <>1 light by un obscuration so 

 extrusive would equal the loss of 5.000 full 

 moons. Whether this, when seen from a star, 



THE SUN-SPOT OF FEBRUARY, 1892. 

 Feb. 6, 10.35 A. u. 



would be sufficiently noticeable to rank our sun 

 as a variable star, as many suppose, is exceed- 

 ingly doubtful. No diminution of either the 

 sun's heat or light upon the earth is shown by 

 delicate tests when the orb is so largely covered, 

 but remains the same in these particulars as 

 when it is spotless. 



Solar Prominences. Solar activity has not 

 been less marked in regard to the prominences 

 than in sun spots. M. Trouvelot, of Janssen's 

 Observatory, at Meudon, France, makes a report 

 of those observed during March, April, and May. 

 lie says that out of 40 observed, 23 belong to the 

 eruptive type. April was especially rich in ex- 

 traordinary outbursts. The base of one seen on 

 April 6 extended 

 12 along the so- 

 lar circumference, 

 and had a length 

 of 90,050 miles, 

 and a height of 



57,570 miles. On j- . , 



the 8th, one, ap- 

 pearing like a 

 candle flame in 

 shape, rose to a 

 height of 71.970 

 miles at 10 h 54 m , 

 and a half- hour 

 later had attained 

 a height of 105,- 



f).~>(l miles. J 



M. .lilies Frlivi, "^ 



on May 5, at Ka- 

 locsa. observed a 

 small one at 10 h 

 "2~> : ". which at 12 h 

 1 1 m began a very 

 rapid upper move- 

 ment, and in eight 

 minutes rose to a height of 140,000 miles, hav- 

 ing ascended at the rate of 228 miles per second. 

 Later, the lower portion faded, but the upper 

 part continued to rise until an elevation of 237,- 

 000 miles was reached. No spot or facula was 



visibly connected with the outburst, and a son 

 spot near was undisturbed. The observer adds 

 that a velocity so great carried the matter into 

 space beyond the sun's attraction, and so, of 

 course, beyond return. May not such eruptions 

 of matter be the source of the sun's corona, and 

 the zodiacal light and of the Gegenshein f 



Sun Spots and Terrestrial Magnetism. It is 

 rather generally conceded, though disputed by 

 some eminent authorities, that during the preva- 

 lence of sun spots the earth's magnetism is in- 

 tensified, and auroral phenomena are more nu- 

 merous. The number of auroras and magnetic 

 disturbances, both of the earth and its atmos- 

 phere during the present year, especially on the 

 apparition of the great sun spot of February 

 last, seem to be proof of its truth. Numerous 

 instances through many years may be cited con- 

 firmatory of the relationship. On the other 

 hand, it is noteworthy that auroral and terres- 

 trial magnetic disturbances often occur during 

 solar quiescence, but the Astronomer Royal, Mr. 

 Christie, argues that, seeing but one side of the 

 sun at such a time, there may have been a spot 

 on the other side. He further says : " There are 

 now three or four marked cases on record of 

 large spots on the sun being coincident with 

 these disturbances on the scale experienced last 

 February, but there are no cases of a large spot 

 being seen without magnetic disturbances." 



Solar Spectrum. Lines in the invisible ultra- 

 violet portion of the solar spectrum have, for the 

 first time, been photographed by H. Deslandres 

 using a Foucault siderostat with an eight-inch 

 Rowland grating. The lines due to hydrogen in 

 this part of the spectrum, first observed by Hug- 

 gins, have also been photographed in the spectra 

 of the protuberances, eight of the ten belonging 

 to the series having been seen. It is believed 

 that from a mountain elevation the other two 

 could be detected. Photographs of the spectra 



; ""<* 



frfllv^aA . fe^ K/^ff \ 



' r**-****^*^* ^^ jB(F'-jKig->> v 



fc^f^L, < *&* 



THE SUN-SPOT OF FEBRUARY, 18M. 

 Feb. 11, 1 p. M. 



of facula} and sun spots show the H and K lines 

 of calcium more intensa than those of hydrogen. 

 Specfroheliographic observations of the sun 

 have been made by Prof. George E. Hale, of 

 Kenwood Observatory, Chicago. In a paper 



