"Aeroplaning has been with us now for more than twenty years, and one might well ask: Why should this peril be only revealing itself in our day? The answer is obvious. In the old days of weak engines, when a hundred horse-power Gnome or Green was considered ample for every need, the flights were very restricted. Now that three hundred horse-power is the rule rather than the exception, visits to the upper layers have become easier and more common. Some of us can remember how, in our youth, Garros made a world-wide reputation by attaining nineteen thousand feet, and it was considered a remarkable achievement to fly over the Alps. Our standard now has been immeasurably raised, and there are twenty high flights for one in former years. Many of them have been undertaken with impunity. The thirty-thousand-foot level has been reached time after time with no discomfort beyond cold and asthma. What does this prove? A visitor might descend upon this planet a thousand times and never see a tiger. Yet tigers exist, and if he chanced to come down into a jungle he might be devoured. There are jungles of the upper air, and there are worse things than tigers which inhabit them. I believe in time they will map these jungles accurately out. Even at the present moment I could name two of them. One of them lies over the Pau-Biarritz district of France. Another is just over my head as I write here in my house in Wiltshire. I rather think there is a third in the Homburg-Wiesbaden district.