eleven-inch telescope of the Wesleyan University. A description of
their appearance is best given in the language of Professor Young,
of Princeton College, who has made these flames the object of most
successful study. On September 7th, 1871, he was observing a large
hydrogen cloud by the sun's edge. This cloud was about 100,000
miles long, and its upper side was some 50,000 miles above the
sun's surface, the lower side some 15,000 miles. The whole had the
appearance of being supported on pillars of fire, these seeming
pillars being in reality hydrogen jets brighter and more active
than the substance of the cloud. At half-past twelve, when
Professor Young chanced to be called away from his observatory,
there were no indications of any approaching change, except that
one of the connecting stems of the southern extremity of the cloud
had grown considerably brighter and more curiously bent to one
side; and near the base of another, at the northern end, a little
brilliant lump had developed itself, shaped much like a summer
thunderhead.

[Illustration: Fig. 34.--Solar Prominences of Flaming Hydrogen.]

But when Professor Young returned, about half an hour later, he
found that a very wonderful change had taken place, and that a
very remarkable process was actually in progress. "The whole thing
had been literally blown to shreds," he says, "by some inconceivable
uprush from beneath. In place of the quiet cloud I had [Page 87]
left, the air--if I may use the expression--was filled with the
flying _débris_, a mass of detached vertical fusi-form fragments,
each from ten to thirty seconds (_i. e._, from four thousand five
hundred to thirteen thousand five hundred miles) long, by two or
three seconds (nine hundred to thirteen hundred and fifty miles)