The simple stratification of vapours, especially during sudden transitions of temperature, may produce very interesting optical phenomena; not by refraction or reflection, but merely by partial obscuration of an object. We have examples of these illusive spectra in the gigantic icebergs seen by Captain Scoresby, and other arctic voyagers, which assumed the shape of towers, and spires, and cathedrals, and obelisks, that were constantly displacing each other in whimsical confusion and endless variety, like the figures of a kaleidoscope. Phipps thus describes their majestic beauty: “The ice that had parted from the main body, they had now time to admire, as it no longer obstructed their course; the various shapes in which the broken fragments appeared were indeed very curious and amusing. One remarkable piece described a magnificent arch, so large and completely formed, that a sloop of considerable burden might have sailed through it without lowering her masts. Another represented a church, with windows, pillars, and domes.” We may scarcely wonder at the mystifications of nature, when she assumes these gorgeous eccentricities, as have been witnessed also in the barren steppes of the Caraccas, on the Orinoko, where the palm-groves appear to be cut asunder; in the Llanos, where chains of hills appear suspended in the air, and rivers and lakes to flow on arid sand; in the lake of the Gazelles, seen by the Arabs and the African traveller; and the lakes seen by Captain Munday, during his tour in India. The very clearness of the atmosphere, like that which floats around the Rhine, renders distance especially distinct; but mountainous regions, from the attraction of electric clouds, afford the highest examples of atmospheric beauty and effect. London and other cities, however crowded with lofty buildings, are not deficient in these aërial illusions. Even from the bridge of Blackfriars I have seen a cumulo stratus cloud so strangely intersect the steeples and the giant chimneys of London, as distinctly to represent a sea-port, with its vessels and distant mountains.