How effective the ocean barrier may be is illustrated by the life of Napoleon. After he had been conquered by the English, Spanish, and Germans he was sent to the island of Elba as an exile. There, however, the water that separated him from France was so narrow that he escaped from exile and returned to lead his armies once more. Then when he was again conquered at Waterloo in 1815 he was sent to the little island of Saint Helena, separated even from Africa by a barrier of 1200 miles of water, and from France by 5000. He could not escape, and so spent the rest of his life there. Like the light house keeper on a rocky island during a storm, he was held in one small place because he had no means of crossing the ocean barrier.
Water as a Defense against Enemies.—Water barriers are as effective in keeping people out as in keeping them in. In prehistoric times our ancestors protected themselves by building their huts of poles and bark on piles in the shallow water near the shore of lakes. The same method is employed at present in New Guinea and other East Indian Islands. A narrow walk leads from the shore across the water to the huts. Part of the walk consists of a plank which can be lifted from the seaward side. Thus when a community is gathered in its huts with the canoes tied under them and the plank raised, enemies have hard work to approach because of the barrier of water.
Water Barriers of Great Britain.—Great Britain is almost like a home on piles with the plank drawn up. It lies close to the coast of the most progressive part of Europe and can communicate freely with the rest of the world when it so desires. Yet it is separated by a narrow body of water which checks and delays whoever would approach uninvited. Although the twenty miles of water between Dover and Calais once made England isolated and backward, they have in the long run been of almost incalculable value to that country. In the later decades of the last century and the earlier ones of the present when the other great Powers of Europe were spending untold millions in preparing vast armies, England was content with only a small army, and saved her money either to develop the industries of peace or to build warships. She knew that because of the water no large army of invaders could quickly be landed on her coasts, and that she was safe from attack. So much did she value her island position that after a tunnel under the English Channel was actually begun, the project was abandoned. England did not wish to build an easy entrance to her front door and thus perhaps give an enemy the oppor tunity to bring in an army. For the sake of safety she proposed to compel those who came to her to come in boats.
When the Great War came, Germany could do little harm to the island empire, try as she might. Even dirigibles and airplanes wrought only intermittent and local destruction on the English coast and in London. The island as a whole was unaffected. In the end, because England's water boundaries had led her to develop a great navy, she maintained control of the sea, and cut off a large share of Germany's foreign commerce, while she herself was being greatly helped by supplies and ammunition from America and else where. When America was ready to enter the war, British ships carried more than a million of our men overseas.
Water Barriers of Japan.—Aside from Great Britain many other large islands have the advantage of protection by water. Only Japan, however, has so stimulating a climate and is located so close to a con tinent that it reaps an advantage similar to that of Britain. Japan, to be sure, has the disadvantage of being far from the center of the land hemisphere and of having no highly advanced neighbors close at hand. On the other hand, her island position has allowed her to develop her civilization without being swamped by the barbarous invaders who have again and again entered China from the bleak deserts of Central Asia. In our day Japan is fast building up a navy and acquiring a large merchant marine, so that she follows closely in the footsteps of Great Britain.
(7) Oceans as Carriers of Commerce.—Although the oceans serve as barriers they are also a great help in transportation, provided people can build the right kind of boats. Transportation by water is the cheapest known method, and hence the oceans carry a vast volume of commerce. Let us compare this method with others.
The Low Cost of Ocean Transportation.—The cost of transporting goods by hand sledges across snowy mountains is sometimes as high as $20 per ton for a single mile. That is what it cost, for example, when the Klondike mines on the Yukon were first opened, and supplies had to be carried from southern Alaska. To carry a ton a mile in the air costs several dollars, although the rate is fast decreas ing. The cost by rail is far lower, being less than two cents in the more thickly settled parts of the United States. On the oceans, however, this low rate falls still lower, that is, to less than a fifth of a cent per mile for a ton. This is only about a tenth as much as by rail, perhaps a hundredth or a thousandth as much as by the air plane or dirigible and a ten-thousandth as much as by sledge over Arctic mountains.