“It’s a good thing the engineer is going to slow down for us,” said Jack.  “We’d never be able to jump off at the rate we’re going.”

“Hark!” exclaimed Mark.  “There goes the whistle!”

The boys listened.  A long, shrill blast cut the summer air, and vibrated back to them over the tops of the cars.

“That isn’t five whistles; it’s one!” cried Jack.  “It’s the call for brakes!  I wonder if anything has happened to the train!”

There was a pause.  Then came another single shriek from the engine’s whistle.  It sounded appealingly, as if the steam monster was in distress.

“Look!  Look!” shouted Mark.  “We are going much faster than we were!”

At the same instant there was a crash and a jolting sound.  The train seemed to break in two parts at about the centre.  The forward section, drawn by the engine, went one way, and the other part, with the gondola containing the boys, in the lead, took another track.  An insecurely fastened switch was responsible for the accident.  The locomotive and nearly half the cars of the train took the main track, while the remainder of the outfit swung on to a siding.

The section of the train with the boys aboard had become a runaway freight!

“What has happened?” cried Mark.

“The train’s broken in two!” shouted Jack.  “Come on!  Help twist the brakes!”

Both boys sprang to the wheel of the gondola.  It was all they could do to give it a few turns, but they managed to make the brake-shoes grip the wheels to some degree, as was evidenced by the shrill shrieking.

“Can you climb up to the top of the box car?” asked Jack.

“Sure!” shouted Mark.  “Go ahead!”

Though Mark was thin, he had a nervous strength almost equal to that of his stouter companion.

“We must set all the brakes we can!” Jack cried.  “That’s the only way to stop the runaway train!”

With their small arms they twisted the wheel on the box car.  They got it as tight as they could, then ran along the top of the vehicle to the next one.  About ten cars down they saw their friendly brakeman.

“That’s the stuff, boys!” he shouted.  “There’ll be a smash-up if we don’t stop the cars!”

He was twisting wheels with all his might.  As fast as they could the two boys went from car to car, setting the brakes.

But in spite of their efforts, and the efforts of another brakeman besides the one they had spoken to, the speed of the runaway freight train increased.  The grade was a steep one, and down the hill the uncontrolled cars rushed.

“I don’t believe we’re going to stop,” said Jack.

“Shall we jump?” asked Mark.

“Not if you want to get a job in the mill or factory,” replied Jack.  “I reckon if you or I jumped that would be the last of us.”

With a rush and a roar the train continued to speed along.  The trees and telegraph poles whizzed past so quickly as to be almost invisible.