1886.] NEW YORK ACADEMY OF SCI-ENCES. 245 



hypothesis. I am not prepared to accept it yet; but certainly 

 not to reject it. 



The Cliromosphere. 



The study of the chromosphere and prominences lias been 

 kept up, very systematically and statistically, by Tacchini in 

 Italy, and with less continuity, but still assiduously, by several 

 other observers. I do not know, however, that any new I'esults 

 of much importance have been arrived at. The list of bright 

 lines visible in their spectra has been a good deal enlarged; and 

 Trouvelot thinks he has observed dark prominences — objective 

 forms that show, black but active, upon the background of bright 

 scarlet hydrogen in the surrounding chroniospheric clouds. It 

 may be that he is right; but so far as I can learn, no other observer 

 of the solar atmosphere has seen anything similar. I certainly 

 have not myself. And I think some of his published observa- 

 tions of velocities of two or three thousand miles a second in the 

 n.otions of the prominences, as evidenced by the displacement of 

 lines in the spectrum, are still more questionable. 



In two or three cases, prominences have been observed since 

 1876 considerably higher than any known previously. In Octo- 

 ber, 1878, I myself observed one which attained an elevation of 

 nearly 400,000 miles (13^')- 



Eclipses and the Corona. 



The sun's corona has been perhaps more earnestly studied than 

 anything else about the central luminary, especially during the 

 four eclipses which have occurred since 1876. At the eclipse of 

 1878, in the midst of an epoch of sun-spot quiescence, the corona 

 Avas found less brilliant than ordinary, and especially deficient in 

 the unknown gas that produces the so-called 1474 Tine — the line 

 which characterizes the spectrum of the corona, and first demon- 

 strated conclusively its solar origin in 1869. But while the 

 corona at this time was less brilliant than it had been formerly, 

 it was far more extensive. At least it seemed so; for at Pike's 

 Peak and Creston, Langley and Newcomb were able to follow its 

 streamers to a distance of 6° from the sun. It is possible, however, 

 that this extension was only due to the superior transparency of 

 the mountain air. 



The Egyptian eclipse of 1882 gave us some interesting results 

 respecting the spectrum of the prominences and the corona. It 

 appears that the light of the corona is especially rich in the 

 ultra-violet, and in the photographs of the spectrum a number 

 of bands are found which have been interpreted, with question- 

 able correctness, I think, as indicating the presence of carbon. 

 The eclipse of 1883 was observed in the Pacific Ocean by French 



