The Antarctic seas, however, are by no means lifeless, but abound not only in fishes,—cod are said to throng in these waters in prodigious numbers,—but several varieties of whales, dolphins, and their kin (which will be described in one of the later chapters), and many kinds of seals, notably the huge sea-elephant, now becoming rare elsewhere. Then, too, the Antarctic islands and headlands are the resort of enormous flocks of certain sea-birds, all different from the Arctic species of their families, which subsist upon the fishes and less creatures in the water, and go to the lonely shores outside the ice-cap only for rest and to make their nests. Of all these the penguins are most numerous and most hardy, and a whole chapter might easily be given to their quaint appearance and quainter ways. It also appears probable that certain migratory birds—especially beach-feeding kinds—regularly visit the Antarctic continent in summer from Patagonia, and breed there. Now what has been gained by all the expense, exertion, and hardship of polar exploration? What has been the charm that has led wise and brave men to overcome terrific obstacles, and turn again with deeper and deeper longings toward the mystic icy regions? Lieutenant Maury has given one answer: “There icebergs are framed and glaciers launched. There the tides have their cradle: the whales their nursery. There the winds complete their circuits, and the currents of the sea their round in the wonderful system of interoceanic circulation. There the Aurora Borealis is lighted up, and the trembling needle brought to rest; and there, too, in the mazes of that mystic circle, terrestrial forces of occult power and vast influence upon the well-being of man are continually at play.... Noble daring has made Arctic ice and waters classic ground. It is no feverish excitement nor vain ambition that leads man there. It is a higher feeling, a holier motive, a desire to look into the works of creation, to comprehend the economy of our planet, and to grow wiser and better by the knowledge.” To polar explorers we owe not only the discovery of the waters, coasts, and archipelagoes that now are accurately outlined upon our maps within the Arctic and Antarctic circles, but vast and valuable products—whale-fisheries, seal-fisheries, cod-fisheries, and many other additions to the wealth of the world from the sea, while the Arctic lands have yielded furs and other valuable things in great quantity. The study of the people living under those adverse northern conditions has been highly instructive, assisting us to reconstruct the life in the primitive world; and what we have learned from the records of the Arctic rocks has thrown a bright and unexpected light upon the antiquity of the globe.