the prism, which will dispose of it in the way already stated. [Illustration: FIG. 45.--VOGEL’S CHROMOSPHERIC FORMS. (“BEOBACHTUNGEN,” DR. H. C. VOGEL.)] And now let us get to the other side, and, looking up through the prism with the aid of a magnifying-glass, see what it has done for us (Fig. 42). The large rectangular opening here is the same as the small one which was visible from the outside, only that it is now magnified, and what was before invisible is seen; the edge of the sun itself is just hidden, but the scarlet flames of the chromosphere have become visible, with a cloudy prominence rising above them. The “flames” are flame-like only in form, for their light is probably due not to any combustion, but to the glow of intensely heated matter; and as its light is not quite pure red, we can, by going to another part of the spectrum, see the same thing repeated in orange, the effect being as though we had a number of long narrow windows, some glazed with red, some with orange, and some with other colors, through which we could look out at the same clouds. I have looked at these prominences often in this way; but I prefer, in the reader’s interest, to borrow from the description by Professor Young, who has made these most interesting and wonderful forms a special study. Let us premise that the depth of the crimson shell out of which they rise is usually less than five thousand miles, and that though the prominences vary greatly, the majority reach a height of nearly twenty thousand miles, while in exceptional cases this is immensely exceeded. Professor Young has seen one which grew to a height of three hundred and fifty thousand miles in an hour and a half, and in half an hour more had faded away. These forms fall into two main classes,--that of the quiet and cloud-like, and that of the eruptive,--the first being almost exactly in form like the clouds of our own sky, sometimes appearing to lie on the limb of the sun like a bank of clouds on the horizon, sometimes floating entirely free; while sometimes “the whole under surface is fringed with down-hanging filaments, which remind one of a summer shower hanging from a heavy thunder-cloud.” Here are some of the typical forms of the quieter ones:-- Fig. 43, by Tacchini, the Director of the Roman Observatory, represents an ordinary prominence, or cloud-group in the chromosphere, whose height is about twenty-five thousand miles. The little spires of flame which rise, thick as grass-blades, everywhere from the surface, are seen on its right and left. [Illustration: FIG. 46.--TACCHINI’S CHROMOSPHERIC FORMS. (“MEMORIE DEGLI SPETTROSCOPISTI ITALIANI.”)] Fig. 44 (Tacchini) is one where the agitation is greater and the “filamentary” type is more marked. Besides the curiously thread-like forms (so suggestive of what we have already seen in the photosphere), we have here what looks like an extended cloudy mass, drawn out by a horizontally moving wind.