It was either very careless or very astute of Nature to leave the entire length of the American continent without a central passage from ocean to ocean, or, having provided such a passage at Nicaragua, to allow it to be obstructed again by volcanic action. This imperviousness of the long American barrier had, as we shall see, important economic and political results, and the eventual opening of a waterway will have results scarcely less important. The Panama Canal will achieve, after more than four centuries, the object with which Columbus spread his sails westwards from the port of Palos--the provision of a sea-route westwards to China and the Indies.