THE FORTNIGHTLY REVIEW. No. XXXVII. NEW SERIES.-JANUARY 1, 1870. CLIMBING IN SEARCH OF THE SKY. AT half-past one o'clock the guide entered my bedroom, pronounced the weather fair, lighted my candle, and then vanished to complete his own preparations. I had been careful to learn whether he really wished to go with me-whether he was embarrassed by either doubt or fear; for it was the first time that a single guide had undertaken to lead a traveller up the mountain. There was no doubt about the matter: he really wished to go. His master (the proprietor of the hotel) had asked him whether he was not undertaking too much. undertaking no more than my companion," was his reply. "I am At twenty minutes past two we quitted the Bel Alp. The moon, which seven hours previously had cleared the eastern mountain-tops with a visible motion, was now sloping to the west. The light was white and brilliant, and shadows of corresponding darkness were cast upon the earth. The larger stars were out, those near the horizon especially sparkling with many-coloured fires. The Pleiades were near the zenith, while Orion hung his sword a few degrees above the eastern horizon. Our path lay along the slope of the mountain, parallel to the Oberaletsch glacier, the lateral moraine of which was close to us on our right. After climbing sundry grass acclivities, we mounted this moraine, and made it our pathway for a time. At a certain point the shingly ridge became depressed, opening a natural passage to the glacier. We found the ice "hummocky," and therefore crossed it to a medial moraine composed of granite débris, and loaded here and there with clean granite blocks of enormous size. Beyond this moraine we found smoother ice and better light, for we had previously journeyed in the shadow of the mountains. We marched upwards along the glacier chatting sociably at times, but at times stilled into silence by the stillness of the night. "Es tagt!" at length exclaimed my companion. It dawns! Orion had moved upwards, leaving space between him and the horizon for the morning star. All the east was belted by that "daffodil sky" which in some states of the atmosphere announces the approach of day in the Alps. We spun towards the east. It brightened and deepened, but deeper than the orange of the spectrum it did not fall. Against this rose the mountains. Silently and solemnly their dark and dented outlines rested against the dawn. The mass of light thus thrown over the shaded earth long before the sun appeared above the horizon, came not from illuminated clouds, but from matter far more attenuated than clouds-matter which maintains comparative permanence in the atmosphere, while clouds are formed and dissipated. It is not light reflected from concentric shells of air of varying density, of which our atmosphere may be rightly assumed to be made up; for the light reflected from these convex layers is thrown, not upon the earth at all, but into space. The "rose of dawn" is usually ascribed, and with sufficient correctness, to transmitted light, the blue light of the sky being reflected; but in each case there is both transmission and reflection. No doubt the daffodil and orange of the east this morning must have been transmitted through long reaches of atmospheric air, and no doubt it was during this passage of the rays that the selective winnowing of the light occurred which gave the sky its tint and splendour. But if the distance of the sun below the horizon when the dawn first appeared be taken into account, it will become evident that the solar rays must have been caused to swerve from their rectilineal course by reflection. The refraction of the atmosphere would be wholly incompetent to bend the rays round the convex earth to the extent now under contemplation. Thus, the reflected light must be transmitted to reach the reflecting particles, while the transmitted light must be reflected to reach the eyes. I imagine that what mainly holds the light of the sun in our atmosphere after the sun himself has retired behind the earth, is the suspended matter to whose presence we owe both the blue of the sky and the morning and the evening red. Through the reverberation of the rays from particle to particle of this matter, there must be at the very noon of night a certain amount of illumination. Twilight must continue with varying degrees of intensity all night long, and the visibility of the nocturnal firmament itself is I believe due, not as my excellent friend Dove seems to assume, to the light of the stars, but in great part to the light of the sun, scattered in all directions through the atmosphere by the almost infinitely attenuated matter held there in suspension. We had every prospect of a glorious day. To our left was the almost full moon, now close to the ridge behind which it was to set. The firmament was as blue as ever I have seen it—deep and dark, and to all appearance pure-that is to say, unmixed with any colour |