Ever since man transported his goods from one place to another he has followed the lines of least resistance and the greatest speed. For that reason rivers were his first natural highway. At the stopping-places along these routes and waterways he built for himself villages, towns, and cities. The biggest of these, however, have always been located at some favorable terminus or harbor. Nineveh, Babylon, Carthage, and Tyre were ancient cities that grew and flourished because they were either the termini or the harbors of advantageous trade routes or excellent stopping-places on great waterways. With the change in the rivers of commerce those cities decayed and passed away. The rise of such cities as Venice and Genoa in the Middle Ages, when they afforded the best ports for the sailing-vessels that connected the caravan routes which came across Asia from the East for their distribution of goods to Europe and the West, was due to the same cause. With the changing of those routes those cities lost their importance and prestige and became what they are to-day. At the present time most of the largest cities of the world are located near inviting harbors or in river-mouths where the great ships of commerce come and go and find refuge. London, Liverpool, New York, Hamburg, Philadelphia, San Francisco, Calcutta, Bombay, Havana, Buenos Aires—to mention only a very few—depend primarily upon their strategic geographic position for their business and their very life. If in time, then, the nearest points of land between continents and countries become the great landing-places for the new passenger and freight ships of the air, it is quite conceivable that the great centres of population and commerce may grow up themselves round those havens. Moreover, if, as the British Civil Aerial Transport Committee and most of the world’s aeronautical authorities are convinced, Cape Town, South Africa—to take but one example—is only three days’ flight by aircraft from Southampton, England, and if all the remotest capitals of the East are only hours or days instead of weeks away from those of the West, there will be such rapid and constant intercommunication that customs practices will become obsolete and one international language may have to be adopted for trade and convenience. Indeed, the only impediment originally put in the way of the Handley Page Company’s London-to-Paris air-line was the violation of customs practices, which is delaying the aeroplanes from making the round trip between breakfast and dinner.