The motives prompting the desirability of human flight from the legendary period to the present time have been very numerous. For the last two hundred years, apart from the war period, we may reasonably assume that the predominant factor has been the rapid transport of personnel or material from one point to another. With this aspect of aviation, aerial navigation is intimately concerned. I want you at the outset to distinguish clearly between the problem of aerial navigation over comparatively short routes—such as from London to Paris— and what is surely the true realm of aircraft, the long distance flights from England to America, India and Australia. In favourable weather the European routes require no more of the pilot than that he should be able to read a map with what, for want of a better term, I will call aeronautical intelligence.