Since 1914, all the belligerents have, with more or less success, considerably developed the scope of their aviation. In France there was too much indecision as to what types should be adopted. The production of standardized machines encountered serious difficulties. Construction was slow. Factories either lacked machinery entirely or were insufficiently supplied with it. Till the autumn of 1915, Germany retained the supremacy in the air. From that time on the situation gradually altered in favor of France, and since the arrival of a large contingent of British machines, the Allies have maintained a marked superiority on the Western Front. When the American air-corps has added its strength to the French the end of the German aviation will be close at hand. It is well nevertheless to note that the Germans, fearing the advent of the American airmen, are now making a powerful effort to double the number of their planes; and, aided by a careful study of the Allies’ machines which have fallen in their lines, are busy constructing more and more formidable examples. The Allies, in the meantime, are daily improving their own, and the Americans have lately had the occasion to see that Italy, one of the most recent aviation recruits, has nearly reached perfection in aircraft construction. In order to render promptly the anticipated aid, the United States should, at the beginning at least, adopt thoroughly tested types of aircraft, of easy control in the air; and should construct several standardized motors. After trial _on the French front_ some types may have to be modified, but only after the American aviation corps has made sure that, in any event, it will have a sufficient number of aircraft in France while awaiting the arrival of the new models. Airplane construction has been hitherto, and will continue to be, constantly progressive. An improvement much needed is a device for the protection of the gasoline tank, which on most of the existing types is too vulnerable and too frequently set on fire. Very often the Germans aim at the tanks rather than at the pilot, as the former are easier to hit and the result is the same. =2. Use and scope of aviation.= Our opinion is that during the present war no real success can be obtained without the help of numerous and daring aviators. During the days preceding an attack (in the trench war) or in order to hide the movements of the troops (in the open field) it is of the utmost necessity to maintain the supremacy in the air. The enemy’s aviation must be entirely blinded. Not one enemy machine must pass over the lines. The captive balloons must be destroyed. In brief, the aviation must be powerful enough to prevent the enemy from having any knowledge of our preparations, and above all from ascertaining the exact point whence the main attack will be launched.