Safe, sure, and sensible prognostications for the future must be based upon events, occurrences, and developments of the past. This is as true in aviation as in any of the older fields of invention or discovery. Too often, during our twenty-four years’ experience in air work, the statement has been heard that this or that cannot be done. Perhaps in no other field have the events of today made liars out of the prophets of yesterday as completely and rapidly as in the air game. When surmising the future of human flight it is far wiser to predict what may be done than to announce what will not be achieved.137