The above experiment is cited only as an indication of what the possibilities are of combining the aeroplane with the dirigible in landing mail or express from dirigibles crossing the Atlantic. Undoubtedly aeroplanes weighing only a thousand pounds, with a flying radius of 600 miles and making 150 miles an hour, will be launched from superdirigibles 500 miles from the journey’s end, especially when airships are to be constructed with 10,000,000 cubic feet of gas, with a 60 per cent gross lift for crew, fuel, freight, and so on, as Mr. Marsh says is quite possible in the immediate future. Experiments for launching aeroplanes from ocean-liners for a like purpose are already under way. The object is to fly the mail for London or New York from the ocean greyhounds as soon as they get within five hundred miles of either coast. This will, of course, cut the flight time from New York to London considerably. As a matter of fact the dirigible might fly over only the great expanse of water from land’s end to land’s end, while the aeroplanes negotiated the remainder of the distance. It is granted that for short flights over land the aeroplane is twice as fast as the Zeppelin, whereas the latter, because it can stay in the air for weeks, is the best adapted for long cruises over large bodies of water. Moreover, the removal of the weight of an aeroplane from a dirigible six hundred miles from its journey’s end would facilitate the remaining flight of the Zeppelin by just so much; it would be equivalent to throwing out ballast to keep a balloon in the air. Perhaps of all the revolutionary scientific developments of the Great War—especially in the field of chemistry—the one that may perform the greatest service to mankind is the steps taken by the Bureau of Mines to produce helium, the non-inflammable gas which has 92 per cent of the lifting power of hydrogen, in sufficient quantities to be used in floating airships! A non-inflammable gas with such a lifting capacity as helium has been the dream of the aeronaut and the dirigible engineer ever since the Robert brothers first conducted their experiments in France in 1784 and found that hydrogen had greater buoyancy than any other gas available in large quantities for balloons; for with it they could jump over the highest peaks of the Himalaya Mountains and the broadest expanses of the Pacific Ocean without danger of the gas igniting from the sun or the engine.