the
smoke-filled, snow-choked shed. Deeper they went and deeper, the
shouts from without fading away, the hot, penetrating sulphur smoke
seeping in even through the closed cab, blackening it until the
electric lights were nothing more than faint pinpoints, sending the
faces of the men to their arms, while the two crouched, waiting
anxiously until the signal should come from ahead.

A long, long moment, while the smoke cut deeper into protesting lungs,
in spite of every effort to evade it, while Old Andy on the engine seat
twisted and writhed with the agony of fading breath, at last to reel
from his position and stumble about in the throes of suffocation. At
last, from ahead, came the welcome signal, the three long-drawn-out
blasts, and the engineer waved an arm.

"Pull that rope!" he gasped toward the first fireman. "For God's sake,
pull that rope! I'm about gone."

A fumbling hand reached up and missed; the light was nearly gone now,
in a swirling cloud of venomous smoke. Again the old engineer
stumbled, and Houston, leaping to his side, supported him.

"Find that rope--"

"I can't see! The smoke--"

Desperately Houston released the engineer and climbed upward, groping.
Something touched his hand, and he jerked at it. A blast
sounded--repeated twice more. In the rear the signal was answered.
Out ground the train to freedom again. It was the beginning of a night
of an Arctic hell.

Back and forth--back and forth--fresh air and foul air--gleaming
lights, then dense blackness--so the hours passed. Sally after sally
the snowplow made, only to withdraw to give way to the pick crews, and
they in turn, gasping and reeling, hurried out for the attack of the
plow again. Men fell grovelling, only to be dragged into the open air
and resuscitated, then sent once more into the cruelty of the fight.
The hours dragged by like stricken things. Then--with dawn--the plow
churned with lesser impact. It surged forward. Gray light broke
through at the end of the tunnel. The grip of at least one snowshed
was broken; but there remained twenty more--and the Death Trail--beyond!

"That's the baby I'm afraid of!" Old Andy was talking as they went
toward the cars, the relief day crew passing them on the way. "We can
whip these sheds. But that there Death Trail--there's a million tons
of snow above it! Once that there vibration loosens it up--we'd better
not be underneath it."

Houston did not answer. The clutch of