Page:Popular Science Monthly Volume 21.djvu/769

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WHAT ARE CLOUDS?

knowledge is set there, or the instinct for conduct. If the instinct for beauty is served by Greek literature as it is served by no other literature, we may trust to the instinct of self-preservation in humanity for keeping Greek as part of our culture. We may trust to it for even making this study more prevalent than it is now. As I said of humane letters in general, Greek will come to be studied more rationally than at present; but it will be increasingly studied as men increasingly feel the need in them for beauty, and how powerfully Greek art and Greek literature can serve this need. Women will again study Greek, as Lady Jane Grey did; perhaps in that chain of forts, with which the fair host of the Amazons is engirdling this university, they are studying it already. Defuit una mihi symmetria prisca, said Leonardo da Vinci; and he was an Italian. What must an Englishman feel as to his deficiencies in this respect, as the sense for beauty, whereof symmetry is an essential element, awakens and strengthens within him! what will not one day be his respect and desire for Greece and its symmetria prisca, when the scales drop from his eyes as he walks the London streets, and he sees such a lesson in meanness as the Strand, for instance, in its true deformity! But here I have entered Mr. Ruskin's province, and I am well content to leave not only our street architecture, but also letters and Greek, under the care of so distinguished a guardian.—Nineteenth Century.

 

WHAT ARE CLOUDS?
By C. MORFIT.

THOUGH the clouds are such familiar objects, very little is known about them, and the processes by which they are formed and give back their moisture to the earth are unsolved mysteries.

They can not be classified as belonging to the solid, fluid, or gaseous form of matter. Yet they are defined as being "a collection of watery particles in the state of vapor, suspended in the air." If they are ordinary vapor, they must be governed by the laws which affect vapors. Brande defines vapor thus: "When liquids and certain solids are heated, they become converted into elastic fluids or vapors, which differ from gases in this respect, that they are not under common circumstances permanently elastic, but resume the liquid or solid form when cooled down to ordinary temperature." According to this definition, clouds can not be composed of ordinary vapor, for under all conditions their temperature must be below the condensing point of water-vapor.

At the elevations at which clouds are often seen, they are in the regions of perpetual congelation; and as they float above the highest