We are now able to judge by results and appreciate the work done. A point of primary importance in active warfare, as we have seen, is the use of the aeroplane for reconnaissance work. Other duties, and there are many, are set forth with admirable clearness by Mr. W. E. Dommett in his little work, _Aeroplanes and Airships_. The book was written at the early part of the war, and on that account is particularly instructive at this point; for it enables us to trace the progress made and the victories won by our airmen. ‘Reconnaissance work for the purpose of co-operation with artillery,’ Mr. Dommett writes, ‘forms the most important function next to scouting. An aerial observer is sent out to determine the position of hostile batteries whose existence may or may not be known by its fire, to determine the strength of the batteries, and how the units composing them are grouped. In addition it is the duty of the observer to look out for troops, stores, or other matters which could and should be subjected to the fire of one’s own batteries. He should supply as far as possible details as to range and elevation necessary for clearing intervening high ground. In addition the observer can report as to the effect of his own side’s artillery, and the manner in which it is failing or succeeding in its object. ‘The value of this form of observation is beyond calculation, in view of the fact that the artillery have not to waste time and ammunition in getting the target. Moreover, the time during which the opposing batteries or forces can do damage is correspondingly reduced. Naturally, much depends upon the accuracy of an observer’s report as to its value, and in this respect it appears that the allied forces are superior to their opponents, and it would seem that this superiority is due not so much to the superiority in the observer’s machine, but to the better self-reliance, intelligence, and powers of initiative possessed by the men themselves. Observation work, it may be said, is generally accompanied by some offensive action on the part of the pilot or accompanying observer.’