As the ratio "weight structure/total lift" is in airships fairly constant, it follows that the ratio "disposable lift/total lift" increases with the dimensions. It is therefore obvious that increased benefits are obtained by building airships of a larger size, and that the bigger the ship the greater will be its efficiency, providing, of course, that it is kept within such limits that it can be handled on the ground and manoeuvred in the air. The proportion of the useful lift in a large rigid, that is the lift available for fuel, crew, passengers, and merchandise, is well over 50 per cent when compared with the gross lift. When the accompanying table is studied it will be seen that with airships of large capacity the available lift will be such that considerable weights of merchandise or passengers can be carried. Capacity in Gross Lift Length Diameter cubic feet in tons in feet in feet 2,000,000 60.7 643 79 3,000,000 91.1 736 90.4 4,000,000 121.4 810 99.5 5,000,000 151.8 872 107.2 6,000,000 182.2 927 113.9 7,000,000 212.5 976 119.9 8,000,000 242.8 1,021 125.5 9,000,000 273.3 1,061 130.4 10,000,000 303.6 1,100 135.1 In airships of their present capacity, in order to obtain the greatest amount of lift possible, lightness of construction has been of paramount importance. With this object in view duralumin has been used, and complicated girders built up to obtain strength without increase of weight. In a large ship with a considerable gain in lift, steel will probably be employed with a simpler form of girder work. In that way cheapness of construction will be effected together with increased rapidity of output, and in addition the strength of the whole structure should be increased. The rigid airship of 10,000,000 cubic feet capacity will have a disposable lift of over 200 tons available for fuel, crew, passengers, and merchandise in such proportions as are desired. The endurance of such a ship at a cruising speed of 45 miles per hour will be in the neighbourhood of three weeks, with a maximum speed of 70 to 80 miles per hour, and a "ceiling" of some 30,000 feet can be reached. This will give a range of over 20,000 miles, or very nearly a complete circuit of the globe. For commercial purposes the possibilities of such a craft are enormous, and the uses to which it could be put are manifestly of great importance. Urgent mails and passengers could be transported from England to America in under half the time at present taken by the steamship routes, and any city in the world could be reached from London in a fortnight.