What may be termed broadly the medical aspects of flying are far more wide–reaching than is generally supposed, especially since such a term embraces both the physiological and psychological aspects of the subject. All the while, therefore, that man acts as the controlling and co–ordinating mechanism of the machine, the study of man in relation to his machine must occupy an important place in the progress of aviation. It is because this aspect of the subject has tended to be somewhat overlooked that I venture to address this Society again to–night.

In the first place I wish to consider what happens when a man learns to fly. As the result of information gleaned by his various senses he is taught, according to his aptitude, to perform or to try to perform certain arm and leg movements which will control the machine safely while it is in the air. To do this, however, in addition to perceiving, he must in certain circumstances display judgment before he acts, although, as he becomes more experienced in flying, he will automatically perform certain movements in response to certain sensations.