Mention airships and most people will immediately raise the question of vulnerability. Large, slow moving, a tempting target, airships could be shot out of the sky by ship or shore guns, or by hostile airplane fire, it is argued, almost as easily as a dinner guest touching his cigaret to a toy balloon. And this is probably true, with reservations, if enemy ships or anti-aircraft batteries or planes were around. But the airship, non-rigid, has no more business in such areas than a British airplane carrier would have to drop anchor in Hamburg harbor. It was because of the imminence of attack from sea or shore or air that neither England nor Germany used airships in the present war, particularly since they would have to use the inflammable hydrogen gas. It was because such attack on American airships from any of these three sources was much less likely—and that we have helium gas, which does not burn—that this country is using them. Their chief field of operations is not off the enemy’s coasts but our own, along that broad ribbon of waters used by our coastwise shipping, an area roughly marked in the Atlantic by the 100 fathom curve, the favorite fishing grounds of enemy submarines. Thousands of miles of blue water, not the narrow lanes of the North Sea or British Channel are between them and the shore guns of an enemy. An enemy fleet, though likelihood of this seems remote, might penetrate those coast waters in attempted invasion, attack the blimps with anti-aircraft fire. But such an enemy, arriving in force, would have either to knock out our Atlantic fleet, or slip past it in surprise attempt. In the remote later contingency, the information relayed back by airship radio that the enemy was moving in would be worth losing airships or any other craft, to get. The third hypothesis, attack by airplane, is also conceivable. But if long-ranging enemy planes were able to get that close to our shores they’d have more important business in hand than wasting time and powder on a helium bubble bobbing in the air, 10,000 feet below—which in any event would already have radioed the news ashore. In the fairly remote contingency that the airplane did choose to attack the blimp, it would find the position of that moving target, flying at an indeterminate distance below, much more difficult to calculate than a fixed target ashore, no easy thing to drop bombs on.