ack, and the four
flashed out of sight toward the west. It is my belief that New York is
next, but the devils are hungry. The beast that attacked us was
ravenous, remember. They need food and lots of it. You will hear of
their feeding, and you can count on four days. Keep Riley
informed--that's your job.

"Now I'm going over the hill. If this experiment works, there's a chance
we can repeat it on a larger scale. No certainty, but a chance! I'll be
back. Full instructions at the hotel in case...." He vanished into the
scrub growth.

"Not exactly encouraging," Thurston pondered, "but he's a good man, Mac,
a good egg! Not as big a brain as the one we saw, but perhaps it's a
better one--cleaner--and it's working!"

They were sheltered under the brow of the hill, but the blast from the
valley beyond rocked them like an earthquake. They rushed to the top of
the knoll. MacGregor was standing in the valley; he waved them a
greeting and shouted something unintelligible.

The gas had mushroomed into a cloud of steamy vapor. From above came
snowflakes to whirl in the churning mass, then fall to the ground. A
wind came howling about them to beat upon the cloud. It swirled slowly
back and down the valley. The figure of MacGregor vanished in its
smothering embrace.

"Exit, MacGregor!" said Cyrus Thurston softly. He held tight to the
struggling figure of Slim Riley.

"He couldn't live a minute in that atmosphere of hydrogen," he
explained. "They can--the devils!--but not a good egg like Mac. It's our
job now--yours and mine."

Slowly the gas retreated, lifted to permit their passage down the slope.

* * * * *

MacGregor was a good prophet. Thurston admitted that when, four days
later, he stood on the roof of the Equitable Building in lower New York.

The monsters had fed as predicted. Out in Wyoming a desolate area marked
the place of their meal, where a great herd of cattle lay smothered and
frozen. There were ranch houses, too, in the circle of destruction,
their occupants frozen stiff as the carcasses that dotted the plains.
The country had stood tense for the following blow. Only Thurston had
lived in certainty of a few days reprieve. And now had come the fourth
day.

In Washington was Riley. Thurston had been in touch with him frequently.

"Sure, it's a crazy machine," the pilot had told him, "and 'tis not much
I think of it at all. Neither bullets nor guns, just this big glass
contr