arbrace breathed, "not again."

He spun and looked towards the river. A wash of waves from the flowing
current lapped against the bank but from the center of the stream the
waters continued to boil. All three men silently watched for a full
minute. From the south where the tail of the convoy was still visible,
a light survey car came racing back down the road towards the river.

It slid to a halt beside the bank and Hall, the senior hydro engineer,
leaped out and came running towards the director and the two junior
engineers.

"Is it still pumping?" he panted anxiously as he surveyed the waters.

The four men eyed the boil for another half minute. Now it was just a
churning pool in the middle of the waters, no longer bubbling higher
than the surface of the waters. "It's still pumping," Hall muttered,
"but something's wrong."

He jumped for his car and grabbed the radio. "Swenson, Baker," he
called, "hold it up. Get that pump-monitoring rig back here on the
double. And get the rest of that gear turned around and headed back
this way. We've got more trouble."

The other three men had walked to the survey car. "What do you think's
wrong," Harbrace asked.

"I dunno," the hydro engineer said. "Maybe the shock triggered the
pile dampers on one of the pumps. Maybe something else." He squinted
at the barely churning waters over the bore hole. "Can't say until we
get a monitor on those pumps. If it's just a malfunction in one of the
units, I can dump another one down there. If it's something else,
we'll have to see then. One thing's sure, they aren't all pumping."

* * * * *

The pump section vehicles had been hauled out of the convoy and were
already pulling up along the riverbank before the rest of the convoy
of heavy equipment was turned around.

In the big monitor van, technicians already were running remote checks
on the underwater pumps. The engineers and the director climbed into
the van to wait the word.

"Number One's O.K.," the section chief reported, "so's Number Two."
The three technicians at the monitor panel punched and re-punched
banks of buttons and switches and watched the patterns on
oscilloscopes.

"Something sour on Number Three," the chief said. "Can't say what
yet."

"Skip over to Four," Hall ordered. "Let's see if that's O.K., then you
can go back to Three."

In two minutes Number Four had been checked out in working order. The
analysis concentrated back to