The proudest inventions of the late nineteenth and early twentieth centuries are but of yesterday when compared with those of the aeroplane and airship. It is, therefore, of the utmost importance that we should consider how the development of aeronautics will affect the future of the human race. Under the present war-time conditions, there exists a grave danger that the aeroplane and the airship will be developed too much for war purposes to the detriment of future commercial uses. The qualities mainly required by the war machine, speed, ability to climb quickly, and compactness, differ entirely from those required by the peace time or commerce-bearing aircraft, which have ability to remain in the air for a great space of time, and to fly greater distances. The extra speed required by the war machine may easily be dispensed with in the commerce-bearing machines, as also may altitude, for whereas the war machine must fly at a height of over 12,000 feet, a height of between 2000 and 3000 will suffice under ordinary conditions, and it will be at this altitude that the best part of the flying will take place after the war. FUTURE NAVIES AND ARMIES OF THE WORLD How will aviation affect warfare in the future? Will it abolish entirely this undesirable condition of affairs, or will it serve to provide added inducements? It is, indeed, a debatable point. If we incline to the latter view, every known argument and theory points to the fact that warfare of the future will be to all intents and purposes instantaneous. There will be no preparatory delay caused by the necessity of placing large armies in the field, of gradually marching forward to establish contact with the enemy, and of carrying out skirmishes which may be prolonged to weeks and months before the actual battle takes place. The belligerent fleets will set off in the dawn or in the darkness, as the case may be, and before twelve hours have elapsed, after entering into the conflict, a definite decision will have been reached. For the airman, there is no falling back to a second line of trenches, to a natural position heavily defended, or to a concrete fortress or emplacement, or to fight a rearguard action. The fight in the air must be to the death, without quarter asked or given, for no prisoners can be taken. The loss of men and material will be tremendous.