ver seen the water in the
flume. I'm going to fill the excavation with water from the flume and so
avoid the wash from the main flow. Save what you can from the river bed.
Leave the excavation to me."

Five minutes later the river bed swarmed with workmen. The cable ways
groaned with load after load of machinery. Jim ran down the trail,
around the excavation and up onto the great block of concrete. The top
of this was just below the flume edge. The foreman of the concrete gang
was aghast at Jim's orders.

"We may have a couple of hours," Jim finished, "or she may come down on
us as if the bottom had dropped out of the ocean. See that everyone gets
out of the excavation."

The foreman looked a little pitifully at the concrete section.

"That last pouring'll go out like a snow bank, Mr. Manning."

Jim nodded. "Dam builders luck, Fritz. Get busy." He hurried into a
telephone booth, even in the stress of the moment smiling ruefully as he
remembered the complaint at the hearing. The booths _had_ been too well
built. Jim's predecessor had been a government man of the old school in
just one particular. Honest to his heart's core, he still could not
understand the need of economy when working for Uncle Sam.

"Have you heard from Iron Skull?" Jim asked the operator.

"He ought to be here now, Mr. Manning," she replied. "I sent the car
over to the kitchen."

"You are all right, Miss Agnes," said Jim. "Tell Dr. Emmet to be near
the telephone. I don't like the looks of this."

Jim hung up the receiver, pulled off his coat and hurried out to the
edge of the concrete section. A derrick was being spun along the
cableway, just above the excavation. A man was standing on the great
hook from which the derrick was suspended. Men were clambering through
the heavy sand up out of the excavation. The man on the edge of the pit
who was holding the guide rope attached to the swinging derrick was
caught in the rush of workmen. He tripped and dropped the rope, then ran
after it with a shout of warning. For a moment the derrick spun
awkwardly.

The man in the tower rang a hasty signal and the operator of the
cableway reversed with a sudden jerk that threw the derrick from the
hook. The man on the hook clung like a fly on a thread. The derrick
crashed heavily down on the excavation edge, and slid to the bottom,
carrying with it a great sand slide that caught two men as it went.

Jim gasped, "My God! I hate a derrick!" and ran down into