a volcanic or seismic disturbance was evident. The connection of
volcanic or seismic action with a flow of water suggested a geyser or
a hot spring of some sort, probably a spring which had broken through
its normal confines some time before, but whose pressure had been
sufficient to prevent the accident until the failure of its flow.

When the flow ceased the building sank rapidly. For the fact
that this "sinking" was in the fourth direction--the Fourth
Dimension--Arthur had no explanation. He simply knew that in some
mysterious way an outlet for the pressure had developed in that
fashion, and that the tower had followed the spring in its fall
through time.

The sole apparent change in the building had occurred above the
one hollow concrete pile, which seemed to indicate that if access
were to be had to the mysterious, and so far only assumed spring,
it must be through that pile. While the vault retained its abnormal
elevation, Arthur believed that there was still water at an immense
and incalculable pressure in the pipe. He dared not attempt to tap
the pipe until the pressure had abated.

At the end of a week he found the vault slowly settling back into
place. When its return to the normal was complete he dared begin
boring a hole to reach the hollow tube in the concrete pile.

As he suspected, he found water in the pile--water whose sulfurous
and mineral nature confirmed his belief that a geyser reaching deep
into the bosom of the earth, as well as far back in the realms of
time, was at the bottom of the extraordinary jaunt of the tower.

Geysers were still far from satisfactory things to explain. There
are many of their vagaries which we cannot understand at all.
We do know a few things which affect them, and one thing is that
"soaping" them will stimulate their flow in an extraordinary manner.

Arthur proposed to "soap" this mysterious geyser when the renewal
of its flow should lift the runaway sky-scraper back to the epoch
from which the failure of the flow had caused it to fall.

He made his preparations with great care. He confidently expected
his plan to work, and to see the sky-scraper once more towering
over mid-town New York as was its wont, but he did not allow the
fishermen and hunters to relax their efforts on that account. They
labored as before, while deep down in the sub-basement of the
colossal building Arthur and his volunteers toiled mightily.

They had to bore through the concrete pile unt