Page:Popular Science Monthly Volume 22.djvu/252
mine, excavated also in the tuff. Its height being about 16 feet (above the sea?), its breadth 12, and its depth about 150, it offers, in its proportion of twelve and a half diameters, the greatest contradiction to all other instances of sea-worn homogeneous rock.
But not only do Cormorant's and Fingal's Cave, each protected by-its breakwater, face the adjacent land and not the open sea, and that land the far-famed Island of Iona, center of art and civilization, "dear to Christendom for more than a thousand years," but from the end of this deep cavity, to which a boat may sail in any ordinary weather, the "Dun" or Hill of "Hy" or Iona rises against the sky, in the middle of the arc of a few degrees subtended by the grand doorway. Until it is shown that a thousand yards of landlocked, iron-bound coast can be cut and tunneled in utter disregard of every known law of mechanical action, the caves in Staffa, on the west coast of Scotland, driven into igneous rock, not modified by local conditions, or in the weak places "of an exposed cliff," can not be classified as merely remarkable instances of caves worn by the sea. Had the learned duke who commenced his description of Iona with these words, "No two objects of interest could be more absolutely dissimilar in kind than the two neighboring islands of Staffa and Iona," "mixed Celtic memories with the Phrygian mount," recalled Athos, Tyre, and Carthage, or even the twin Island of Lerins, he might have hesitated to put them in sharp antithesis to say that only an accident of geography could unite their names, or with "the mighty surge" of personal and social authority drowned the faint cry for relief which reached his ears, and declined even to consider the solution here offered of a problem whose complex factors he had so forcibly stated.
By C. PIAZZI SMYTH,
ASTRONOMER ROYAL FOR SCOTLAND.
WHAT may be done with the spectroscope in the matter of weather is, for the present at least, confined almost entirely to the question of rain—as, Will it rain, or will it not; and, if it will, heavily or lightly? The manner in which the spectroscope accomplishes this useful part is by its capacity for showing whether there is more or less than the usual quantity of watery vapor permeating the otherwise dry gases in the upper parts of the atmosphere, this watery vapor not being by any means the visible clouds themselves, but the invisible water-gas out of which they have to be formed, and by means of which, when over-abundant, they obtain their privilege for enacting rain-fall. So that never were wiser words uttered and more