Frank knew at once that they had been discovered by a band of Comanches.

The savages had crept up in the darkness and had for a time been puzzled at the make-up of the Steam Horse.

This had delayed their attack.

But it came, nevertheless, and in a furious manner.

The arrows began to fly in literal clouds. There was great danger of getting struck, as Frank well knew.

The young inventor quickly pressed the spring which shut the metal sides of the wagon.

They were now perfectly secure from the arrows.

But there was an amount of danger in a close combat which Frank did not relish.

Accordingly he decided to make a move from the spot.

There was sufficient steam up to give the Horse fair speed.

Frank pulled on the reins and sent the Steam Horse forward.

Barney and Pomp went to the loopholes and opened fire upon the red foe.

Of course it was firing at random in the intense darkness.

The headlight of the Horse lit up for a ways in advance. But the red foe were swarming all about.

The din was something terrific as the red foe kept up a perpetual yelling and howling.

“Bejabers, I niver kin git a fair shot at the omadhauns,” cried Barney, “they do be dodging about so much like the devil, shure one kin niver tell which way to fire.”

“Jes’ yo’ fire anywheres—jes’ de same as I does!” cried Pomp. “Yo’s dead suah for to hit some on ’em.”

“Begorra, that’s phwat I’m after doing,” cried the Celt.

But Frank was anxious to get away from the foe.

Of course they had the best of the running fight, but it was impossible to tell just where the course they were pursuing would take them to.

In the intense darkness they might at any moment run into some quicksand or saline lake.

Frank endeavored to keep the Steam Horse up to a good rate of speed.

He hung to the brake handle and kept a keen watch ahead, as far as he could see in the radius of light from the headlight of the Steam Horse.

For what seemed an interminable length of time this sort of thing went on.

Then it came to a sudden termination.

Of a sudden the whooping and yelling ceased, and the savages disappeared.

Nothing more was seen or heard of them for a time.

Frank was not a little surprised and puzzled.

“I wonder what game they are up to now?” he muttered. “I think we will keep a sharp look out.”

He was not deceived.

He did not by any means credit the assumption that the savages had given up the contest.

This was not a reasonable hypothesis.

“Begorra, mebbe we’re comin’ to some hole in the ground, or something av the sort!” cried Barney, suspiciously.

“It will do no harm to keep a good watch anyway,” rejoined Frank.

And this was done.

The Steam Horse now went on at a moderate pace, and Frank increased, if anything, his watchfulness.

The Comanches did not show up, and seemed to have wholly abandoned the fight.

Time wore on, and it was near dawn when through the shadows Barney saw a dark object which caused a sharp cry to escape his lips.

“Luk out, Misther Frank!” he cried. “Shure wud yez see phwat is ahead.”

Frank’s gaze was blinded by the headlight’s glare for a moment.

But he closed the throttle and brought the Horse to a stop.

He was not a moment too soon.

They were at the base of a high cliff of rock which towered above fully a thousand feet.

If Barney had not seen the cliff just in time they would certainly have dashed full into the cliff.

This no doubt would have damaged the Steam Horse greatly if not destroyed it entirely.

“A lucky escape!” cried Frank, “but where in the world are we, Barney? I saw nothing of any elevation when we camped last night.”

“Shure, sor, we’ve cum a good ways,” declared Barney.

“We must have. Is this the base of some high hill, or——”

“Shure it’s in a canyon I think we are, sor!” cried Barney. “Don’t yez see that there be walls all about av us?”

“You’re right!” cried Frank, as the rapidly growing dawn began to make the vicinity clear.

Then the voyagers were treated to a genuine surprise party as the vicinity became quite plain.

They were in what seemed like a mighty amphitheater fully two miles in circumference, hemmed in with precipitous cliffs in almost a complete circle.

Where the circle was broken was visible the entrance to this peculiar amphitheater.

Through this, by a singular chance, the Steam Horse had entered.

Frank understood the situation at a glance.

“Upon my word!” exclaimed the young inventor in amazement and trepidation, “we’ve stumbled into a nice trap now, haven’t we?”

“Begorra, I should say so!” ejaculated Barney, with a grimace of comical sort.

“I done fink dat am a fac’,” assented Pomp, seriously.

“I wonder if those savages did not know it and hung back on purpose?”

A chilling thought struck Frank.

Indeed it was not impossible but that they were even now in waiting at the narrow entrance to the place.

If so it would be a nice little ambush for the Steam Horse to fall into.

One thing was sure.

The best thing to be done was to get out of that spot just as soon as possible.

Accordingly Frank at once headed the Horse for the exit.

But as they drew near to the narrow passage, Frank found his worst fears confirmed.

He stopped the Horse.

“It’s just as I thought,” he muttered. “We’re in a trap.”

Fully a hundred hostile Comanches were blocking the entrance to the amphitheater, if such it could be called, with stones.

For the Steam Horse to pass over the barricade was utterly impossible.

They were hemmed in—trapped!

It was a thrilling realization.

For a moment all three stood looking at each other in blank amazement and indecision.

“Bejabers, it’s a foine thrick they have played on us this toime!” cried Barney.

“Golly! I specs dem Injuns knowed all de time we’d be suah fo’ to come in dis place,” exclaimed Pomp.

“Well, we will have to fight our way out,” said Frank, desperately.

Then a happy thought seemed to strike him.

“But first let us see if there is not some other method of leaving the place,” he cried.

“Bejabers, I don’t think that,” cried Barney, looking doubtfully at the high surrounding cliffs.

“Perhaps not!”

However, Frank turned the Horse about and began to make a circle of the enclosure.

But everywhere the cliffs seemed to present the same impregnable face.

There did not seem a crevice anywhere by which one could have hoped to crawl out of the place.

It was a hopeless outlook.

There seemed no other way but to fight a way out through the pass.

This would not have looked so hopeless had it not been for the obstructions in the shape of the heavy stones.

The Horse could not pass over these and to remove them the voyagers would have had to alight from the wagon and thus expose themselves.

But Frank started the Horse boldly for the pass.

The savages had intrenched themselves behind the barricade and were ready to receive the attack.

A flight of arrows came hurtling through the air.

These did no harm falling lightly against the steel shutters.

But part of the Comanches had fire arms and these now began to open fire upon the Steam Horse.

Frank sent the Horse up to within a safe distance of the barricade.

Then Barney and Pomp opened fire with their Winchesters.

Whenever they were able to draw a bead upon any of the red foe they could make their shots tell.

But this it was not so easy to do, for the Comanches kept well under cover of the rocks.

Every subterfuge was made to draw them out into the open.

While the Comanches defended the pass they did not attempt to make an attack upon the Steam Horse.

Their purpose seemed solely and simply to be to hold the pass and prevent the escape of the captives.

“Their game evidently is that of a long siege!” declared Frank positively. “It will be a hard outlook for us, for I see no other way to get out of this place.”

Barney scratched his head vigorously and sat down to think a moment.

“Bejabers, we can’t fly out,” he declared finally.

“No,” replied Frank.

“Shure it’s stuck we are.”

“To a certainty.”

“What the divil will we do?”

“That’s the question.”

Irish wit, however, was not to be long baffled. Barney suddenly cried:

“Sure I have an ijee.”

“Indeed!” exclaimed Frank. “What is it?”

“Begorra, wud yez luk up yonder to the top av that cliff?”

Frank did look up.

This was to the top of the high walls of the pass.

“Well,” he said curtly, “what are you driving at, Barney?”

“Shure, sor, if yez will give me the lave, I’ll climb up there an’ roll down big stones on the head av the rascals an’ fire many a good shot at thim, too. Av I don’t make it too hot for thim to sthay in the pass then me name ain’ O’Shea.”

A glad cry burst from Frank’s lips.

He saw the feasibility of the plan at once.

“Good for you, Barney!” he cried. “It takes an Irishman to solve a riddle after all. You are a brick!”

“Shure I’m not a Mick, sor, savin’ yer presence!” protested Barney.

“I said a brick. Not a Mick!”

“Shure I beg yure pardon, Misther Frank. It’s a gintleman yez are, an’ so was yer fayther afore ye.”

But Frank was now busy figuring the chances of success of the new plan.