With some curiosity he took up a tube of tin about a foot long and four inches in diameter. On examining it he saw that through the centre was a second tin tube of about an inch in diameter. Holding it as a telescope towards the light he could see through the inner tubes and noticed that near one end of it a small steel catch was protruding. Further and minute examination revealed that to the catch could be attached a time-fuse already concealed between the inner and outer tubes. "This is evidently some ingenious form of hand grenade," whispered Kennedy. "It's all ready for filling. But why, I wonder, should a tube run through the middle in this way?" He was pondering with it in his hand, when his gaze suddenly fell upon something else which was lying close to the spot where he found the tin tube. It was a thin ash walking-stick. On Kennedy taking it up it presented a peculiar feature, for as he grasped it there sounded a sharp metallic click. Then, to his surprise, he discovered that he had inadvertently released a spring in the handle, this in turn releasing four small steel points half-way down the stick. "Curious!" he whispered to his well-beloved, for Drost was sleeping below entirely unconscious of the intruders in his secret laboratory. "What connection can the stick have with the grenade--if not for the purpose of throwing?" He therefore placed the inner tube over the little knob of the stick, and found that it just fitted, so that with plenty of play it slid down as far as the projecting points which, after striking the little steel catch which would be connected with the fuse, allowed it to pass over freely and leave the stick. "Ah! I've got it!" he whispered excitedly. "The grenade can be carried in the pocket with perfect safety, until when required it is placed over the handle of the stick and whirled off. As it passes the projections on the stick the time-fuse is set for so many seconds, and the grenade automatically becomes a live one. A very pretty contrivance indeed!-- very pretty!" he added with a grin. "This, I must admit, does considerable credit to Ortmann, Drost and Company." Ella, who had been standing by, holding the electric torch, stood in wonder at the discovery. Truly, some of her father's inventions had been diabolical ones. Kennedy saw that the ash-stick had been finished and was in working order. All was complete, indeed, save the filling of the deadly grenade, the attaching of the fuse, and the painting of the bright tin. For fully five minutes the air-pilot stood in silence, deeply pondering. Then, as a sudden idea occurred to him, he said quickly: "I must take this stick, Ella. I'll be back again by four o'clock, and will leave it just outside the front door. You take it in, and replace it exactly as we found it." He lost no time. In five minutes he had crept from that dark house of mystery and death, and, carrying the stick, returned across Hammersmith Bridge.