With a jump like that of a dog released from the leash, the motor cycle seemed to spring forward.  Indeed Joe must needs hold on, and as he was not so favorably seated as was his chum, it became a matter of no little trouble to maintain a grip with his legs and hands.

“We—­sure—­are—­going—­some!” muttered Joe.  But he did not open his mouth any more.  It was too dangerous at the speed they had attained.  A jolt over a stone, or a bit of wood, might send his teeth through his tongue if he parted his jaws.  So he kept quiet.

Ahead of them the carriage swayed and swerved.  The horse was a speedy one, but no creature of bone, blood, muscles and sinews can distance a fire-spitting and smoke-eating machine like a motor cycle.  The distance was gradually being cut down.

But now, just ahead of them, was the curve, immediately beyond which was the broken bridge, and also the temporary one, shunting off at a sharp angle from the main highway.

“Look out!  Hold on!” once more cried Blake, speaking in quick tones.

For a moment Joe wondered at the added caution, and then he sensed what Blake was about to do.

To one side of them stretched a level field.  The road made a slight detour about it, just before meeting the ravine, and by crossing this field it was possible for the boys to reach the bridge ahead of the swaying carriage.  But at the speed they were now running it was dangerous, and risky in the extreme, to run across the uneven meadow.  Blake, however, evidently was going to chance it.

“Hold fast!” he cried once more, and Joe had no more than time to take a firmer grip on the bar in front of him, and to cling with his legs to the foot supports and saddle, than they were off the road, and into the green field.  The fence had been taken down to allow for the storage of bridge-building material in the meadow.

“Now we’ll get him!” cried Blake, but he spoke too soon.  For the motor cycle had not gone ten feet into the uneven field, jolting, swaying and all but throwing off the moving picture boys, than the sound of the explosions suddenly ceased, and the machine began to slacken speed.

With a quickness that was added to by the rough nature of the ground, the motor cycle slowed up and stopped.

“What’s the matter?” cried Joe, putting down his feet to support the machine.

“Something’s busted—­gasoline pipe, I guess!” cried Blake.  “Come on!  We’ve got to run for it!”

The accident had occurred only a short distance from the road.  Together the two chums, leaping clear of the motor cycle, made for it on the run.

But they were too late.  They had a glimpse of the runaway horse dashing straight at the fence barrier.

The next moment there was a splintering crash, and he was through it.

“Oh!” cried Blake.

The thunder of the horse’s hoofs on what was left of the wooden approach to the broken bridge drowned his words.