When they have attained proficiency in this direction, they return to their regiments, and are afterwards called upon, from time to time, to undergo "refresher" courses of military flying. The criticism which is levelled against this scheme is that officers should be permanently attached to the air-corps, and should never be allowed to relinquish their flying duties. Experts who hold this view affirm that "refresher" courses are not sufficient to keep a man thoroughly _au fait_ with such special work as military aviation. As a matter of fact, the relief which has been expressed at the taking up by the War Office of any definite programme, has had the effect of robbing such criticisms as these of their sting. If the plan described were to be adopted as a permanent policy there would, indeed, be grave cause for complaint. French and German military pilots are placed once and for all in the air-corps, and are not withdrawn. But the scheme of our authorities must only be regarded as a beginning. Directly any really definite work is done, the value of a well-equipped air-corps will be so strikingly demonstrated that there should be little difficulty in extending the Government programme. The ideal, undoubtedly, is a large and extremely skilful corps of pilots and observers, who do nothing save perfect themselves in their aerial duties. An airman cannot have too much actual flying practice; in every aerial voyage he makes, he learns some useful lesson. The French policy is: once a military airman, always a military airman. Naturally, with the avowed policy of training these 100 military pilots, the War Office has found it necessary to acquire more machines. From time to time, therefore, since the announcement of this scheme, machines have been bought from famous French firms—notably a Breguet biplane, a Nieuport monoplane, and a Deperdussin monoplane. But such purchases have only been made to meet the most pressing needs of the flying school. What will precede any large orders for war aeroplanes is a carefully-conducted and stringent test of military machines, which will be thrown open to the world. The conditions for these trials, which will be held in England under the auspices of the War Office, probably some time in July this year, were issued in December last. Critical comment has granted their practicability, and it is agreed that the successful machines will represent all that is best in military aviation. One criticism, however, is that the sum of money which will be expended in prizes, £11,000, is not sufficiently generous. In connection with the 1911 French military trials, a sum of more than £50,000 was earmarked by the Government to be expended in prizes, and in orders for successful machines.