Teddy Gerrod straightened up and beat his hands together.
"Forty-seven below," he said to the soldier behind him. "Put a marker here."
He moved off to the right. Already a dozen little flags showed where the temperature reached that degree. Teddy was drawing what he would have termed an isothermal line—a line where the temperature was the same. He was making a circle about a large part of the open clearing on the ice floe. Other flags led back into the mist, marking a path, and from time to time a party of four or five fur-clad soldiers arrived from the fort, dragging a loaded sledge behind them. They emptied the load from the sled, turned, and vanished into the mist again. A small pile of drills, explosives, and two of the squat trench mortars had already been made.
When the circle of little red flags had been completed, two signal-corps men set up their instruments and accurately located the center. Directly under that spot, if Teddy's reasoning was correct, the new cold bomb was resting. The sledge from the fort arrived again, bearing a curious trench catapult for flinging bombs. Four long strips of black cloth were unrolled, under direction of the signal-corps men, pointing accurately to the center of the circle. No one had been able to approach nearer, thus far, than thirty yards from the center. At that distance Teddy's thermocouple indicated a temperature of more than seventy-two degrees below zero, and flesh exposed to the air was frostbitten on the instant. What the temperature of the air might be directly above the cold bomb could only be conjectured.
One of the infantry men from the fort, the best grenade man in the garrison, now picked up a Mills grenade, and after carefully picking out the target with his eye, aided by the strips of black cloth, flung the small missile. A hole perhaps four feet deep and twice as much across was blasted in the brittle ice. A second, third, and fourth grenade followed. At the end of that time the size and depth of the hole had been doubled.
The trench catapult was set up. Half a dozen grenades were bundled together and flung into the now much enlarged opening in the surface of the ice. There was no explosion. One automatically braced oneself for the report, and the utter silence that succeeded the disappearance of the grenades came as a peculiar shock.
"Too cold," remarked Teddy to the young lieutenant in charge.
The lieutenant nodded stiffly.
"We'll try again."
A second batch of grenades was flung into the hole, and the same quiet resulted.