Hereupon--though not as throwing very much light on the question after all--I told Hubbard of my own surmise with regard to Rooke. He looked rather quickly up. "What, little Queerfellow? He's--er--all right, isn't he? What about him? Tell me about him." This too I told him as well as I was able. And I may say that I noted with pleasure, as perhaps the real beginning of a valued friendship, that there did not seem to be any question in Hubbard's mind as to what kind of man I was myself. He was quite content to accept my summing-up of Monty. "So it's between 'em, you think, whatever it is?" "Or else I give it up," I replied. "I wonder if you're right," he mused.... "But then," he added suddenly, "what about all that time he spent in the cellar?" From that point our conversation took for a time a curious little turn. For Hubbard, while seeming to have no explanation that as a sensible man he must not reject as fantastic, seemed nevertheless to be reluctant to let something go. He seemed to hint and to dismiss and then to hint again, to come to the brink of saying something and then to leave it unsaid after all. And again I had the feeling that though he had known Philip Esdaile for only two years as against my twenty, in some things he might be the familiar and I the outsider. Then again he seemed to decide to take a risk. He spoke to the paper-weight in his palm. "You don't happen to know anything about these new sound-appliances, do you?" he asked. "No. Which are they?" "Oh, there are a lot of 'em," he answered again, half evasively. "There's sound-ranging, of course. Then there's the hydrophone. And as a matter of fact the best brains in the world to-day are trying to cut-out sound--aeroplane propellers and so on.... What I mean is Esdaile's not hearing anything. I suppose it's just possible that he didn't. All a matter of where the sound-wave hits. You remember the broken windows in the Strand when Fritz used to come over and drop his eggs? First a broken one, then two or three whole ones, then broken ones again, all along the street? Well, this might have been one of those dumb intervals. Otherwise he _must_ have heard. And I should have thought he'd have felt the vibration too." "He's admitted he thought he heard something." "Pooh, there was no mistaking it. If he didn't recognize it we can take it he didn't hear it. If we believe him, of course." "Don't you believe him?" "Yes," Hubbard answered without a moment's hesitation. "Then----?" "Oh, I suppose it means I'm on the wrong track," Hubbard replied.