In venturing to enter this arena of the aviation world I am fully aware that I am guilty of no small amount of temerity, because in comparison with many of my audience I am a very raw recruit, both as an aviator and as a medical officer in the R.A.F. I can only plead in excuse for accepting the kind invitation of your Secretary to address you this evening- that I have done a good deal of hard thinking on the subject in the time at my disposal and have obtained some experimental results which appeared of interest to others qualified to judge; and further, it is only by free ventilation apd discussion of one's ideas that progress can be obtained in such a new field of science as aviation.