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ery day. Moreover, the next year Huggins
was able, by using a wide slit, to see the
whole of a prominence and note its shape.
Prominences are classified, according to their
form, into ”flame” and ”cloud” prominences,
the spectrum of the latter showing calcium,
hydrogen, and helium; that of the former
including a number of metals.
The D line of sodium is a double line,
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