applied the current. But it was no use. With a
blinding flash and a report like that of a gun a fuse blew out, and that
crippled the car completely so far as the electric current was
concerned.

"Everybody jump!" cried the conductor. "There's a curve at the foot of
the hill, and we'll all be killed if we stay on!"

One by one the passengers leaped from the car. Several were badly hurt
by the falls they got. Meanwhile the trolley was tearing down the hill
at a terrific rate of speed.

"Shall we jump?" asked Mark of Jack.

"We'll be killed if we do," was Jack's answer.

"And we'll be killed if we stay aboard," said Mark.

"Not if I can help it," cried Jack as he started for the rear platform.

"What are you going to do?" asked Mark.

"Put on the other brake. They never thought to try this one! Maybe it
will work and stop the car!"

Then Mark saw what Jack was up to and went to help him. The shabbily
dressed man seemed undecided what to do. He stood up, holding to the
straps to prevent himself from being tossed from side to side as the
runaway trolley swayed. He watched the boys curiously.

The lads, reaching the rear platform, twisted at the brake handle with
all their strength. They could feel that the chain was still intact. But
would the shoes grip the wheels with force sufficient to stop the car?

There was a shrill screech as the brakes were applied by the boys. With
all their might they turned the handle, winding the chain up tighter and
tighter. At last they could not budge it another inch. Then they waited
anxiously.

The car never slackened its speed. So great was the momentum that had
both sets of brakes been in working order it is doubtful whether they
would have stopped the vehicle. The speed was so great now that one of
the journals became hot and the oily waste that was packed in it caught
fire, making what railroad men term a "hot box".

"I guess we're done for," groaned Mark.

"We certainly haven't checked the speed any," Jack admitted. "But wait a
minute."

He began stamping on the floor of the platform.

"What you doing?" cried Mark, for he had to shout to make his voice
heard above the roar and rattle of the car.

"Putting on the sand," replied Jack, as he kicked at the plunger which,
being depressed, let a stream of fine gravel out on the rails. "The
wheels are gripped I think, and are slipping on the rails. This may help
some."

"Let me give you a hand," exclaimed a voice, and