The sailor, to whom once the route was trackless and untrodden, now consults a volume of charts which he has obtained from the National Observatory, and finds his course laid out upon data derived from analogy and oft-repeated experience. He takes this or that direction in accordance with known facts of the prevalence of winds or the motion of currents. He keeps a record of his own experience, that in its turn it may be useful to others. He has plans and surveys which give him the bearings of every port, the indentations of every coast, the soundings of every pass. Beacons warn him of reefs and sunken rocks, and buoys mark out his course through the shallows of sounds and straits. A modern light-house costs a million dollars, and a breakwater involves the finances of a state. If a new light-house is erected, or is the warning lamp for any reason discontinued, upon any coast, the fact is made known to the commerce of all nations by a "Notice to Mariners," inserted in the marine department of the newspapers most likely to meet their eye. A vessel at sea is safer from spoliation than is the traveller upon the high road or the sojourner in a city; for there are robbers and depredators everywhere upon the land, while there is not a pirate on the ocean. There are well-laden treasure-ships in the Panama and California waters, as in the times of Drake and Anson; but the world is much older than it was, and buccaneers and flibustiers now only infest the land. In short, the ocean, once a formidable and repellant element, now furnishes Christian food and healthful employment to millions. Instead of serving to affright and appall the dwellers upon the continents which it surrounds, it renders their atmosphere more respirable, it affords them safe conveyance, and raises for them a school of heroes. The ocean, then, has a history: it has a past worth narrating, adventures worth telling, and it has played a part in the advancement of science, in the extension of geographical knowledge, in the spread of civilization and the progress of discovery, which it is eminently worth our while to ponder and digest. Its gradual submission to invasion from the land, its successive surrender of the islands in the tropics and the ice-mountains at the poles, its slow but certain release of its secrets, its final abandonment of its exclusiveness, form--with a multitude of attendant incidents, accidents, battles, disasters, shipwrecks, famines, robberies, mutinies, piracies--the theme and purpose of these pages. Although the ocean has lost its terrors and has given up its dominion of dread over the mind of man, it is still poetic, and has been often made to assume a profound moral significance and furnish apt religious illustrations. In this connection, we cannot do better than to quote, from Dr. Greenwood's "Poetry and Mystery of the Sea," a passage which strongly and beautifully enforces this view:--