M. Flammarion gives in his “Voyages” some very interesting and amusing particulars, as well as many valuable scientific observations. During one ascent he remarked that the shadow of the balloon was _white_, and at another time dark. When white the surface upon which it fell looked more luminous than any other part of the country! The phenomenon was an _anthelion_. The absolute silence impressed the voyager very much. He adds, “The silence was so oppressive that we cannot help asking ourselves are we still alive! We appear to appertain no longer to the world below.” M. Flammarion’s observations on the colour of what we term the sky are worth quoting—not because they are novel, but because they put so very clearly before us the appearance we call the “blue vault.” He says,—speaking of the non-existence of the “celestial vault,”—“The air reflects the blue rays of the solar spectrum from every side. The white light of the sun contains every colour, and the air allows all tints to pass through it except the blue. This causes us to suppose the atmosphere is blue. But the air has no such colour, and the tint in question is merely owing to the reflection of light. Planetary space is absolutely black; the higher we rise the thinner the layer of atmosphere that separates us from it, and the darker the sky appears.” [Illustration: Fig. 298.—The “Eagle” of M. Godard.] Some beautiful effects may be witnessed at night from a balloon, and considering the few accidents there have been in proportion to the number of ascents, we do not wonder at balloon voyages being undertaken for mere pleasure. When science has to be advanced there can be no objection made, for then experience goes hand-in-hand with caution. It is only the ignorant who are rash; the student of Nature learns to respect her, and to attend to her admonitions and warnings in time. The details of the ascents of famous aeronauts give us a great deal of pleasant and profitable reading. The phenomena of the sky and clouds, and of the heavens, are all studied with great advantage from a balloon, or “aerostat,” as it is the fashion to call it. The grand phenomena of “Ulloa’s circles,” or _anthelia_, which represent the balloon in air, and surrounded by a kind of glory, or aureola, like those represented behind saintly heads, appear, as the name denotes, opposite to the sun.