We were still standing, peering out through the rising mist, when Dorothy spoke out excitedly. “That’s the next clue, there’s nothing else that will do so well,--the hunt for disappearing iron.” “What good will that do?” said Tom. “We know where iron has disappeared, and we’ve run everything down as far as we could. It isn’t likely that Heidenmuller or the man went around shooting off signs for fun.” “Of course not,” answered Dorothy impatiently. “But don’t you see the man must have had a laboratory, or lodgings, anyway, somewhere in London, if he got his data and his power from Dr. Heidenmuller here. When Dr. Heidenmuller let his discovery get away from him, it killed him, and caused all the metal which it reached to disappear. Now, the man hasn’t been killed by his weapon, unless it happened very recently, but it’s perfectly possible that he might have allowed some of his magic substance to escape without injury to himself. If that happened, it would destroy any metal at hand. If we could find some place where iron disappeared, we might get a direct clue to the whereabouts of the man. It’s worth trying, anyway.” “I’m sure it is,” I cried. “Tom, you old doubter, speak up and admit Dorothy knows twice as much about it as you and I put together.” “I guess not,” said Tom firmly. “There may be something in this, if we could get track of everything that bore on disappearing iron, London over; but,” he went on, “talk about a needle in a hay stack. You went up against a hard enough proposition in running down Heidenmuller’s laboratory here, but this new deal is far worse. You can’t advertise.” “No, I don’t see how you can,” remarked Dorothy, a trifle discouraged. “Oh, this thing’s easy enough,” I broke in. “I wish everything was as simple. Inside of two days, I’ll have all the information that London holds with regard to disappearing iron.” “How can you get it?” cried the three in unison. CHAPTER XIV “By using the device which ministers at the same time to the vanity and the necessity of man, the clipping bureau,” I replied. “We will subscribe to that distributor of special information, and get every clipping for the last six months that bears upon falling blinds, signs lost, or stolen iron. They can ransack the files for us, and send us the result of their labor.” “Just the trick,” cried Tom enthusiastically. “We’ll go straight to work on it. Now let’s get out of here.” Bearing our precious tube of gas, we started back, leaving Swenton to close the laboratory and follow later. No such delightful wandering was provided for our return as for our coming. All too soon we were back at the Savoy with our day’s labor over, ready to follow the new trail wherever it might lead us.