The elements of astronomy; a textbook . Fig. 57. — Qiiiescent Prominences. its lines are conspicuous along with those of hydrogen. The D3 lineis not the only helium line, but the chromosphere spectrum containsat least three others that are always observable, besides several thatoccasionally make their appearance. The H and K lines of calciumare also, like those of hydrogen and helium, always present as brightlines in the chromosphere; and several hundred lines of the spectraof iron, strontium, magnesium, sodium, &c, have been observed init now and then. 203. The Prominences and Chromosphere ob
The elements of astronomy; a textbook . Fig. 57. — Qiiiescent Prominences. its lines are conspicuous along with those of hydrogen. The D3 lineis not the only helium line, but the chromosphere spectrum containsat least three others that are always observable, besides several thatoccasionally make their appearance. The H and K lines of calciumare also, like those of hydrogen and helium, always present as brightlines in the chromosphere; and several hundred lines of the spectraof iron, strontium, magnesium, sodium, &c, have been observed init now and then. 203. The Prominences and Chromosphere observable withthe Spectroscope. — Janssen was so struck with the brightnessof the hydrogen lines that he believed it possible to observethem in full daylight, and the next day he found it to be so;and not only this, but he found also that by proper manage-ment of his spectroscope he could study the forms and struc-ture of the prominences nearly as well as during the eclipse. § 203] THE PROMINENCES. 145 Lockyer in England, a few
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