Each one knew the need for haste; each waited every moment for the terrible blast of gun-fire that would jar their bodies to a lifeless pulp or, by detonating their own explosive, destroy them utterly. But they carried the flasks again to the top, and the three of them worked breathlessly to place their whole supply where McGuire directed.
The massive barrel of the gun was beside them; it was held in tremendous castings of metal that bolted to anchorage in the ground. One great brace had an overhanging flange; the explosive was placed beneath it.
Professor Sykes had come prepared. He attached a detonator to one of the flasks, and while the other two were placing the explosive in position he fastened two wires to the apparatus with steady but hurrying fingers; then at full speed he ran with the spool from which the wires unwound.
McGuire and Althora were behind him, running for the questionable safety of the sand-hills. Sykes stopped in the shelter of a tiny valley where winds had heaped the sand.
“Down!” he shouted. “Get down—behind that sand dune, there!”
He dropped beside them, the bared ends of the wires in his hands. There was a battery, too, a case no larger than his hands. Professor Sykes, it appeared, had gained some few concessions from his friends, who had learned to respect him in the field of science.
One breathless moment he waited; then—
“Now!” he whispered, and touched the battery’s terminals with the bare wires.
To McGuire it seemed, in that instant of shattering chaos, that the great gun itself must have fired. He had known the jar of heavy artillery at close range; he had had experience with explosives. He had even been near when a government arsenal had thrown the countryside into a hell of jarring, ear-splitting pandemonium. But the concussion that shook the earth under him now was like nothing he had known.