whistle shriek.

"Fwhat are they doing now?" called Callahan to his fireman.

"They've gone inside again," was the reply.

"Go back an' thry the tank," was the command; and Jimmy Shovel climbed
over the coal and let himself down feet foremost into the manhole. When he
slid back to the footplate his legs were wet to the mid shin.

"It's only up to there," he reported, measuring with his hand.

Callahan looked at his watch. There was yet a full hour's run ahead of
him, and there was no more than a scant foot of water in the tank with
which to make it.

Thereafter he forgot the Naught-seven, and whatever menace it held for
him, and was concerned chiefly with the thing mechanical. Would the water
last him through? He had once made one hundred and seventy miles on a
special run with the 1010 without refilling his tank; but that was with
the light engine alone. Now he had the private car behind him, and it
seemed at times to pull with all the drag of a heavy train.

But one expedient remained, and that carried with it the risk of his life.
An engine, not overburdened, uses less water proportionately to miles run
as the speed is increased. He could outpace the safe-guarding mail, save
water--and take the chance of being shot in the back from the forward
vestibule of the Naught-seven when he had gained lead enough to make a
main-line stop safe for the men behind him.