(2) Critics seldom descend into mines.

(3) There is extra pay.

The disadvantages are so obvious that they need not be enumerated here.

In these trenches we have been engaged upon a very pretty game of subterranean chess for some weeks past, and we are very much on our mettle.  We have some small leeway to make up.  When we took over these trenches, a German mine, which had been maturing (apparently unheeded) during the tenancy of our predecessors, was exploded two days after our arrival, inflicting heavy casualties upon “D” Company.  Curiously enough, the damage to the trench was comparatively slight; but the tremendous shock of the explosion killed more than one man by concussion, and brought down the roofs of several dug-outs upon their sleeping occupants.  Altogether it was a sad business, and the Battalion swore to be avenged.

So they called upon Lieutenant Duff-Bertram—­usually called Bertie the Badger, in reference to his rodent disposition—­to make the first move in the return match.  So Bertie and his troglodyte assistants sank a shaft in a retired spot of their own selecting, and proceeded to burrow forward towards the Boche lines.

After certain days Bertie presented himself, covered in clay, before Colonel Kemp, and made a report.

Colonel Kemp considered.

“You say you can hear the enemy working?” he said.

“Yes, sir.”

“Near?”

“Pretty near, sir.”

“How near?”

“A few yards.”

“What do you propose to do?”

Bertie the Badger—­in private life he was a consulting mining engineer with a beautiful office in Victoria Street and a nice taste in spats—­scratched an earthy nose with a muddy forefinger.

“I think they are making a defensive gallery, sir,” he announced.

“Let us have your statement in the simplest possible language, please,” said Colonel Kemp.  “Some of my younger officers,” he added rather ingeniously, “are not very expert in these matters.”

Bertie the Badger thereupon expounded the situation with solemn relish.  By a defensive gallery, it appeared that he meant a lateral tunnel running parallel with the trench-line, in such a manner as to intercept any tunnel pushed out by the British miners.

“And what do you suggest doing to this Piccadilly Tube of theirs?” inquired the Colonel.

“I could dig forward and break into it, sir,” suggested Bertie.

“That seems a move in the right direction,” said the Colonel.  “But won’t the Boche try to prevent you?”

“Yes, sir.”

“How?”

“He will wait until the head of my tunnel gets near enough, and then blow it in.”

“That would be very tiresome of him.  What other alternatives are open to you?”

“I could get as near as possible, sir,” replied Bertie calmly, “and then blowup his gallery.”

“That sounds better.  Well, exercise your own discretion, and don’t get blown up unless you particularly want to.  And above all, be quite sure that while you are amusing yourself with the Piccadilly Tube, the wily Boche isn’t burrowing past you, and under my parapet, by the Bakerloo!  Good luck!  Report any fresh development at once.”