Twice the diggers disturbed a dead German, buried evidently under the parapet. Once a significant crumbling of the earth and fall of a few heavy clods threatened a collapse where the gallery was under the edge of the trench. The spot was hastily but securely shored up with infinite caution and the least possible sound, and after that the Subaltern had the explosive charges brought along and connected up in readiness. Then, if the roof collapsed or their work were discovered, the switch at the shaft could still be pressed, the wires would still carry the current, and the mine would be exploded. At last the Subaltern decided that everything was ready. He carefully placed his charges, connected up his wires again, cleared out his tools, and emerged to report 'all ready.' Now the 'touching off' of a good-sized mine is not a matter to be done lightly or without due and weighty authority, and that because more is meant to result from it than the upheaval of some square yards of earth and the destruction of so many yards of enemy trench. The mine itself, elaborate and labour-making as it may have been, is, after all, only a means to an end. That end may be the capture of a portion of the ruins of the trench, it may be the destruction of an especially strong and dangerous 'keep,' a point of resistance or an angle for attack. It may even be a mine to destroy a mine which is known to be tunnelling into our own trenches, but in any case the explosion is usually a signal for attack from one side or the other, and therefore requires all the usual elaborate arrangements of reinforcements and supports and so on. Therefore the Sapper Subaltern, when he had finished his work and made his report, had nothing to do but sit down and wait until other people's preparations were made, and he received orders to complete his work by utterly and devastatingly destroying it. The Subaltern found this wait about the most trying part of the whole affair, more especially since he had for a good many days and nights had so much to occupy his every moment. He received word at last of the day and hour appointed for the explosion, and had the honour of a visit of inspection from a very superior officer who pored long and painstakingly over the paper plans, put a great many questions, even went the length of walking down the communication trench and peering down the entrance shaft, and looking over the sandbagged wall through a periscope at the section of German trench marked down for destruction. Then he complimented the Subaltern on his work, declined once again the offer of a muddy mackintosh and an invitation to crawl down the mine, and went off. The Subaltern saw him off the premises, returned to the shaft and donned the mackintosh, and crawled off up his tunnel once more.