thquakes increased in frequency until Rick and Scotty felt as though
the ground never ceased shuddering.

The air became noisy with planes as the Military Air Transport Command
began ferrying in troops. Flight after flight of huge transports roared
in for a landing at the Calor airport, discharged the soldiers, and took
off again at once.

And still the diamond hunt continued.

Then, at one o'clock in the afternoon, Hartson Brant called a halt.

"The magma's moving up through the dike," he reported. "It's now or
never. Captain Montoya, we will ask the troops to clear the area.
Commander Jameson, withdraw all men and equipment except those necessary
for the final packing. Dr. Cantrell, please be ready to place the
charge at dawn tomorrow."

The final phase of the operation swung into action. The troops gathered
at Redondo and marched shoulder to shoulder southward along the mountain
slopes. They herded the diamond seekers before them, sometimes with
enough roughness to overcome protests, but mostly with little
difficulty. They herded the population entirely around El Viejo, and
established a perimeter from Calor northward, with the population
confined to a narrow segment of the island along the seaward side.

Loud-speaker trucks roamed along the perimeter, reassuring the people.
Military disaster units cooked huge quantities of food and prepared
thousands of gallons of coffee and reconstituted milk. American soldiers
played with cute little San Luzian kids and--after the diamond seekers
became convinced they had never had a chance to find diamonds--the whole
affair became one big picnic.

But it was a picnic with overtones of fear.

Rick and Scotty watched the placement of the nuclear explosive--a simple
steel can, from the outside--in the big hole. They watched the remaining
handful of Seabees load tons of rock in after it. Only the wires
connecting the device to a radio firing unit on the beach gave evidence
that an explosion equal to ten thousand tons of TNT was about to take
place.

Rick asked, "Won't all those rocks keep the volcano from erupting?"

Hartson Brant smiled. "Rick, compared with the force of the volcano,
that atomic device is like a firecracker compared with a hurricane. But
even to the nuclear explosion those rocks won't mean much. They're just
to confine it a little."

The night passed. San Souci was empty of people. The Seabees were back
aboard ship. The scientific instruments were in pl