The Cucuracha slide, in the Culebra cut, is ample proof of the unstable nature of the volcanic soil of the Cut. It presents an effective barrier across the Canal, created suddenly and removed only by long effort. Could such a slide be created from the air? The means already exist
it is said, estimates the number of troops eventually necessary for this purpose as 20,000, which will require the construction of one or more of the largest army posts in our service.
For the past six years, at least, the problem of fortifying the Panama Canal has engaged the attention of our ablest military authorities and, naturally, every precaution has been taken to insure, as far as possible, its impregnability. But, during this time, a new factor in warfare has gradually been developed—a factor whose vast importance is just beginning to be realized by even the most progressive strategists and tacticians. I refer to what the French call "the Fourth Arm"—the aeroplane.
When we stop to consider it, the progress that aviation has made during the past five years is simply amazing. At the end of 1908, not over half a dozen machines were flying, with a duration record of about an hour and a half, a speed of some forty miles per hour and a height record of 320 feet. At this writing, the duration record is over sixteen hours without landing, a height of three and eight-tenths miles has been attained, a speed record of 126 miles per hour has been made, continents have been crossed, seas have been traversed, mountain ranges and deserts have been flown over and the number of machines is legion. France alone has over 800 military aeroplanes ready for service and is making a desperate effort to maintain the mastery of the air; while Germany, Russia, Great Britain, Austria, Italy and Japan are training aviators and providing machines as fast as possible. In short, military experts are coming to realize that the aeroplane is not only a factor in warfare, but may become a decisive factor.
It is not of their use as "the eyes of the army" in securing and transmitting in formation that I wish to speak here, how ever, but of a newer and, some believe, more important development—as carriers of incendiary bombs and high explosives.
Over a year ago, in France, the writer demonstrated, beyond doubt, that remarkable accuracy can be attained in dropping bombs from an aeroplane by placing twelve out of fifteen bombs within a square of about 120 feet from a height of over one half mile and at a speed of nearly a mile a
