Great crowds lined the field on every side. In the centre stood a small group of prominent officials. Among them I recognized President Poincaré. They were examining a new weapon with which French aeroplanes would henceforth go "sausage-hunting" over the German lines. Even the casual visitor to the front is struck by the great number of observation balloons which both sides use in their efforts to keep informed of the preparations being made by the enemy. Every few miles a captive balloon or "sausage" wafts lazily over the German lines, fairly far behind the lines, but at an altitude sufficient for observation purposes. Against these "monsters" aeroplanes heretofore had been powerless. Their machine guns fired bullets which, even if incendiary, were too small to set on fire the gas-containing envelope. The aircraft cannon carried by some of the French machines also proved useless. The holes their projectiles made in the balloons were too small to allow a sufficient quantity of air to enter and cause an inflammable mixture. The rockets, which were being examined as I landed at Le Bourget, solved the problem. Four are mounted on each side of an aeroplane. At the head of each rocket is a large dart, resembling a salmon-gaff. The tails of the rockets are wound into spiral springs, which are held in sockets. All eight rockets are fired at once. They are ignited as they leave their sockets, and travel with lightning speed. Swinging lazily above the field was a captive balloon. At one end of Le Bourget was a line of waiting aeroplanes. "This is the second. They have already brought down one balloon," remarked the man at my elbow. The hum of a motor caused me to look up. A wide-winged double-motor Caudron had left the ground and was mounting gracefully above us. Up and up it went, describing a great circle, until it faced the balloon. Every one caught his breath. The Caudron was rushing straight at the balloon, diving for the attack. "Now!" cried the crowd. There was a a loud crack, a flash, and eight long rockets darted forth, leaving behind a fiery trail. The aviator’s aim, however, was wide, and, to the disappointment of every one, the darts fell harmlessly to the ground. Another motor roared far down the field, and a tiny "appareil de chasse" shot upward like a swallow. "A Nieuport," shouted the crowd with one voice. Eager to atone for his "copain’s" failure, and impatient at his delay in getting out of the way, the tiny biplane tossed and tumbled about in the air like a clown in the circus-ring. "Look! He’s looping! He falls! He slips! No, he rights again!" cried a hundred voices as the skilful pilot kept our nerves on edge. [Illustration: A heavy bombarding-machine.]