"'I have called you gentlemen together,' he says to his officer, 'in order to ask you to corporate with me. I shall fire some rockets from the slag heap to-night about ten o'clock. On the first of these signals the Germans will open a very heavy cannonade on our trenches. I'll trouble you to have your men all in the dug-outs, and under cover at a quarter to ten!' "That night, soon after the Colonel, Tommy and I started off for the slag heap in the dark, taking with us a bundle of rockets. My idea was at last going to be tested--what do you think it was, Sir?" I discreetly pretended my utter inability to guess. "Why, nothing more or less than to hoist these German blokes with their own petard, so to speak. We were going to fool them by giving them signals in their own code. Well, after stumbling and groping about for half an hour," McNab continued, "we arrived at the spot near where we had overlooked the spy. "'I think this is the ledge from which I fell,' Tommy whispered as we crawled on. The next instant the Colonel disappeared, and the little procession came to an abrupt standstill. A crashing noise was heard as the old man with a quarter of a ton of slag went tobogganing down the stone-shod slope. "'This _is_ the spot,' Tommy said tersely. And up to us came hoarse whispered curses as our ole man tongue-lashed us for a full minute in gross and detail. "'Lie quite still, Colonel,' I whispered, 'the Hun swine-dogs may send up a flare if they hear us.' "But no flare flared, and no sniper sniped. "'This game gives me the blooming creeps,' old Tommy muttered shudderingly, thinking of Huns and guns three miles deep all round. After that the Colonel struggled clear of the 'alf ton of slag atop o' him. Tommy and I wandered a little more until we got down to the old man. Here we halted. 'Here's the place where we left the dead spy,' said Tommy, his eyes peering into the darkness of the V-shaped cutting. 'I can still see Fritz lying in the corner. We had better get right over _this_ side. Come on!' "'I see,' said the Colonel. 'This is the key of the position. It overlooks the German trenches and when the spy was using his flash lamp he could not be observed by the men in our lines.' "'Good thing we short-circuited his little game,' reflected Tommy hugging an arm full of rockets.