It was a tough task, for five yards' thickness of sand-bags had to be removed before the mine chamber was reached. It was a nerve-racking task when the huge store of explosive stood revealed in the glare of an electric torch. At any moment the stuff might explode. "It'll save the sanitary squad a job if it does," remarked one of the men grimly, "Anyway, it's a mighty quick death--none of that rotten hanging about." Five minutes later more work resulted in the discovery of two insulated wires that met in a metal box containing the primer. With a sigh of relief Ralph severed the wires. Unless there were more sets the immediate danger was over. All this time the place was trembling under the concussion of heavy shells overhead. Presently with remarkable suddenness the shelling ceased. "What does it mean, I wonder?" thought Ralph. "It can't be that our fellows have been compelled to give ground. We must endeavour to get out of this hole and see what's doing." Bidding the men bring a small quantity of the explosive with them, Setley retraced his way. During his absence more rubble had fallen, and the roof of the Tank was covered with a tightly jammed mass of broken bricks. "Looks healthy, sir," commented Alderhame. "Yes," agreed Ralph. "It seems as if we are to stop here until we are dug out, unless we can contrive to blow away this mass of rubble. Unfortunately, I am not expert in the art of the use of explosives." "There's one of our fellows who used to be a quarryman," announced the sergeant. "I'll get him." In answer to his call, a little sharp-featured Welshman stepped forward. "Yes," he replied, in a shrill falsetto. "I have blasted stone for the last three years. I do not know what strength this stuff has, but we'll try." Taking about seven pounds of the explosive the Welshman rammed it in a cavity in the wall of rubble, filled in the mouth with sand-bags brought from the mine gallery, and laid a fuse of cordite, obtained by opening half a dozen cartridges. "All ready, sir," he reported. "Get back all of you. I'll fire it. It'll burn for thirty seconds, I guess, and that'll be enough for me to hook it." The rest of the crew entered the Tank, the door being left open for the brave Welshman to gain shelter before the explosion. Presently a match flickered in the gloom, followed by the sizzling of the sticks of cordite, which burned with comparative slowness when not under pressure. With a furious bound the Welshman leapt into the Tank, his head butting into the stomach of a comrade who was holding the door in readiness to slam it the moment the man had gained shelter. Even in the midst of danger the two began mutual recriminations, the Welshman asking "what the silly idiot meant by getting in his way," the other retorting by requesting him in future to use his eyes to see where he was going.