matter; it is a laboratory for purification, in which that matter is recompounded, and wrought again into wholesome and healthful shapes; it is a machine for pumping up all the rivers from the sea, and conveying the waters from their fountains on the ocean to their sources in the mountains; it is an inexhaustible magazine, marvellously adapted for many benign and beneficent purposes. . . . To evaporate water enough annually from the ocean to cover the earth, on the average, five feet with rain; to transport it from one zone to another; and to precipitate it in the right places, at suitable times, and in the proportions due, is one of the offices of the grand atmospheric machine. This water is evaporated principally from the torrid zone. Supposing it all to come thence, we shall have, encircling the earth, a belt of ocean three thousand miles in breadth, from which this atmosphere evaporates a layer of water annually sixteen feet in depth. And to hoist up as high as the clouds, and lower again all the water in a lake sixteen feet deep, and three thousand miles broad, and twentyfour thousand long, is the yearly business of this invisible machinery. What a powerful engine is the atmosphere! and how nicely adjusted must be all the cogs, and wheels, and springs, and compensations of this exquisite piece of machinery, that it never wears out nor breaks down, nor fails to do its work at the right time, and in the right way".
One other selection, from the chapter on "The Salts of the Sea", will be sufficient as illustrative material. "Take for example", he writes, "the coral islands, reefs, beds, and atolls, with which the Pacific Ocean is studded and garnished. They were built up of materials which a certain kind of insect quarried from the sea