Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. Certainly a man who intends to fly should be consti tutionally sound this point is important. When in an aeroplane, one passes very quickly through the air, and such rapid movement – and also the effect of varying altitudes – entail a certain physical strain. A man with a weak heart might find himself affected adversely by flying; While one Whose lungs were not sound might find that his breathing was impeded seriously by a swift passage through the air. More than one fatality, doubtful as to its exact cause, has been attributed to the collapse of a pilot who was not organically sound, or who ascended when in poor health. And here again is an important point. No man, even a normally healthy man, should attempt to pilot a machine in flight when he is feeling unwell. In such cases the strain of flying, and the effect of the swift motion through the air, may cause a temporary col lapse; and in the air, when a man is alone in a machine, any slight attack of faintness may be sufficient to bring about a fatality.