y feet or more, and intensely hot still deeper. The Neoliths took a
single look at it, then turned, and raced for home.

"Didn't like our looks. Let's go back."

They wandered about the world, investigating various peoples, and proved
to their own satisfaction that there was no Atlantis, not at this time
at any rate. But they were interested in seeing that the polar caps
extended much farther toward the equator; they had not retreated at that
time to the extent that they had by the opening of history.

They secured some fresh game, an innovation in their larder, and a
welcome one. Then the entire ship was swept out with fresh, clean air,
their water tanks filled with water from the cold streams of the melting
glaciers. The air apparatus was given a new stock to work over.

Their supplies in a large measure restored, thousands of aerial
photographic maps made, they returned once more to space to wait.

Their time was taken up for the most part by actual work on the enormous
mass of calculation necessary. It is inconceivable to the layman what
tremendous labor is involved in the development of a single mathematical
hypothesis, and a concrete illustration of it was the long time, with
tremendously advanced calculating machines, that was required in their
present work.

They had worked out the problem of the time-field, but there they had
been aided by the actual apparatus, and the possibilities of making
direct tests on machines already set up. The problem of artificial
matter, at length fully solved, was a different matter. This had
required within a few days of a month (by their clocks; close to thirty
thousand years of Earth's time), for they had really been forced to
develop it all from the beginning. In the small improvements Arcot had
instituted in Stel Felso Theu's device, he had really merely followed
the particular branch that Stel Felso Theu had stumbled upon. Hence it
was impossible to determine with any great variety, the type of matter
created. Now, however, Arcot could make any known kind of matter, and
many unknown kinds.

But now came the greatest problem of all. They were ready to start work
on the data they had collected in space.

"What," asked Zezdon Afthen, as he watched the three terrestrians begin
their work, "is the nature of the thing you are attempting to harness?"

"In a word, energy," replied Arcot, pausing.

"We are attempting to harness energy in its primeval form, in the form
of a