On and on he crawled, grimly soliloquising that much more of this mode of progression would make him imagine that he was a new type of serpent, for as he approached the outer fringe of scrub he literally moved on his stomach.
Proceeding thus he passed between two large thorn bushes. Beyond was a slight artificial depression in the ground, on the bottom of which were hundreds of metal cartridge cases.
By the peculiar pungent odour he knew that they had been fired within the last twelve hours. Some were trodden into the loose earth, which bore numerous indications of having been trampled both with boots and bare feet.
"By Jove!" he thought. "Fritz has cleared out."
Even as the idea flashed across his mind a rifle-shot rang out on his left.
Promptly Wilmshurst flattened himself to the ground, and waited breathlessly for further developments. The weird silence was maintained save for the distant croaking of bullfrogs in a marsh.
"Booby trap!" he declared, and cautiously groped around to find out if he had incautiously touched a fine wire. At a radius of his extended arm he found nothing of that nature. Perhaps, after all, a sniper was concealed in the bushes on his left, for the bullet had not been directed at him.
Bent upon investigating the mystery Wilmshurst crept round the intervening bushes. Before he had traversed thirty yards his head came in contact with the stock of a rifle. The weapon was lashed to a couple of stout bamboos. Fastened to the trigger was a short piece of wire, to which in turn was tied a length of raw hide. The subaltern gave a chuckle of satisfaction. His discovery confirmed his surmise that the investing force had raised the siege, leaving rifles so arranged that they would fire automatically after various intervals in order to convey the erroneous impression that the bush was still held in force.
The raw hide cords had been placed in position during the heat of the day. After dark the heavy dew moistened the hide and caused it to contract until the tension upon the trigger was sufficient to release the bolt action and detonate the cartridges.
A similar ruse, embodying more ingenuity, had been practised by the British troops during the successful evacuation of the Gallipoli peninsula; but in this case the fixed rifles were fired by means of a small trickle of water dropping from an upper receptacle into a lower one. To the latter was tied a cord, the other end of which was fastened to the trigger. As soon as half a gallon of liquid entered the lower tin can, resulting in a pressure of about seven pounds on the trigger, the rifle was fired.