sand miles are so intimately related with the opposite shores of Europe and Asia that the Sahara constitutes a far more effective break in social continuity than does the Mediterranean. In the days of air navigation which are coming, sea-power will use the water-way of the Mediterranean and Red Seas only by the sufferance of land-power, for air-power is chiefly an arm of land-power, a new amphibious cavalry,, when the contest with sea-power is in question.
But North and South America, slenderly connected at Panama, are for practical purposes insular rather than peninsular in regard to one another. South America lies not merely to south, but also in the main to east of North America; the two lands are in echelon, as soldiers would say, and thus the broad ocean encircles South America, except for a minute proportion of its outline. A like fact is true of North America with reference to Asia, for it stretches out into the ocean from Behring Strait so that, as may be seen upon a globe, the shortest way from Pekin to New York is across Behring Strait, a circumstance which may some day have importance for the traveller by railway or air. The third of the new continents, Australia, lies a thousand miles from the south-eastern
