"Put a row of them about a hundred yards in front of the zariba," continued Fane. "In the event of the Senussi attempting to rush our defences we can set fire to the stuff."
"I fail to see how, Major," objected Captain M'Bride, "unless someone applies a light to it; and the effect is, to a certain extent, lost if we have to do that before the Arabs are actually over the line of tins. Remember we have no time-fuses."
"You have some good marksmen, I presume?" asked Major Fane.
"Some first-class shots."
"Then we could lash up this metal matchbox to one of the tins, and ignite the contents by means of a rifle-bullet."
"It might be feasible," remarked the skipper.
"I think I know of a better plan, sir," said Webb. "We have the Very's pistol and signal-cartridges. I saw them lying over yonder. At the critical time a few bullets could be shot at one of the tins, and, when the petrol runs out, it could be fired by a signal-bullet from the pistol."
"Ah, that's more like it, Mr. Webb!" said the skipper warmly. "Now set to work and get your men to place the tins in position. Heap sand on the outward face so that they are rendered as inconspicuous as possible. Meanwhile, Major, I think I will get you to pass an opinion upon our defences on the right flank."
The Sub had barely completed his task of constructing what was expected to form an efficient "fire barrage" when one of the seamen patrolling the shore gave the warning cry of "Submarine coming in, sir."
Almost simultaneously a rifle cracked from somewhere about five hundred yards inland. A Senussi sniper had approached between the sand-dunes, while, at a distance of a mile or so, was a large armed party of mounted nomads from the desert.