“Hurrah for a railroad ride over the mountains!” cried Darry, as they proceeded to the station. “Wonder how long it will be?”

“Twenty-four miles, so the professor said,” responded Sam. “He said Caracas is only six miles away and the mule path isn’t over nine miles long. But the lowest part of the mountain is nearly a mile high and the train has to do a lot of twisted traveling to get over it.”

“Wonder they wouldn’t tunnel the mountain,” suggested Frank.

“That’s what they are talking of doing,” put in Hockley, who felt just then like being sociable. “Somebody has got a franchise, but it’s going to take millions of dollars.”

The professor had been looking after tickets. He soon returned and when the train came along they all got in the first-class compartment, which was not much better than a very ordinary car at home. The car sat so close to the rails that the tops of the wheels had to be bridged over, interfering somewhat with the seating capacity.

Soon came a long whistle, the conductor waved his hand and the train moved away, through the town and in full view of the ocean. The speed was fair, but nothing to what the boys were used to at home, yet this was not to be wondered at, for they were climbing steadily along the face of the mountain. Up and up they went until Frank, who sat at a window overlooking the water hundreds of feet below, could not help but shudder.

“If we should drop off here, there wouldn’t be anything left of us,” he said to Sam.

“I guess we won’t drop off,” was the reply. “But say, it does make a fellow dizzy to look down, doesn’t it?”

The professor sat with them and pointed out several places of interest as they sped onward. “You see the tracks follow the mule road in many places. The path is about nine miles long and in former days it was the only means of communication between Caracas and the sea, outside of an old Indian trail further to our right.”

They soon dashed into a tunnel and out again, and then began another climb along the mountain side. As they reached a higher elevation they noticed that the air was cooler.

“We are coming to another tunnel,” said Mark, as they swung around a sharp curve.

“Yes, and we’re running swifter than before,” put in Sam.

The next instant found them in the tunnel, rushing past great masses of black rocks. Nothing but smoky lamps lit up the car and Mark was gazing at one of these, when of a sudden the train came to such a short stop that everybody was pitched forward.

“We’ve struck something,” cried Darry, as he scrambled up from the floor, to which he had been hurled.

“Is anybody hurt?” came anxiously from Professor Strong, as soon as the shock was over and the car came to a standstill.

“I pinched my hand on the seat,” answered Mark. “But it doesn’t amount to anything.”

The passengers were climbing out of the train, to learn the cause of the sudden stoppage. They found the train hands gathering about the engine and with them was a track-walker who had given them the signal to stop.

“There has been a cave-in ahead, he says,” said Professor Strong, after listening to the track-walker. “If the train hadn’t stopped we might all have been killed.”

The track-walker talked excitedly, in Spanish and in broken English, and some of the party went ahead to inspect the cave-in. A large mass of rocks had fallen and it was easy to see that the track would not be cleared for several hours.

“Now what’s to do?” grumbled Hockley. “I’m sure I don’t want to stay boxed up in this tunnel till they clear that stuff away.”

“I don’t see what else we can do,” answered Sam, “unless we walk all the way back to La Guayra.”

“How far are we from Caracas?” asked Mark, of one of the passengers.

“About three miles,” was the answer.

“Can’t we walk to that place?” asked Mark, of Professor Strong. “We have nothing but our little shoulder valises to carry.”

“I think we can walk it,” said the professor. “I will ask how the track ahead is.”

He did so and was informed that, so far as the track-walker knew, it was all clear. Accordingly they started out, the professor and Mark leading the way and the others following close behind.

They were in the shadow of the mountain so that the fierce rays of the sun did not reach them. They had left the tallest portion of the mountain behind, so the way was now all more or less down grade.

“I move we get off the railroad track and rest,” said Hockley, after half a mile had been covered. “We’re in no especial hurry to get to Caracas.”

The professor and the others were willing, and leaving the track they found shelter along a hillside covered with tropical trees and bushes. As they stepped away from the railroad they heard a humming sound and saw a handcar approaching, filled with men and tools, bound for the scene of the cave-in.

“They must have telegraphed for those fellows,” said Darry. “They will get the road into shape again in short order.”

It was very pleasant to lie under the trees in the shade, and Frank was so sleepy that he soon dropped into a doze. Mark walked around inspecting the surroundings, and to get a better outlook climbed a small cliff which arose not far away.

From the elevation of the cliff Mark could get a good view of the valley stretching out in the direction of Caracas and could even see some of the white buildings in the distance. Then the youth walked along the cliff to where there was a turn, around a series of rough rocks.

There had been a heavy dew on the mountain the night before and in the shady spots this had not yet dried off. As he made the turn his foot trod in some moisture and slipped, and down he went on his knee. He tried to save himself by clutching at some vines but these gave way and over the cliff he plunged on to some loose rocks below.

Fortunately for Mark, the fall was not a deep one or some bones might have been broken. The loose stones and earth gave way beneath his weight and allowed him to slide swiftly under the cliff into a long and narrow hollow. Here he went with a splash into some water up to his knees and some of the dirt and stones came after him, sending the moisture all over him.

Mark was so surprised at the turn of affairs that for the moment he stood perfectly still, panting for breath. It was dark around him, the only light coming from the opening above, which was fully a dozen feet over his head. In front of him was the rocky cliff raising itself in a curve over his head. Behind him was the wall of dirt. The split, if such it may be called, extended a dozen feet in one direction and out of sight in the other.

“Now I’m in a pickle and no mistake,” he muttered, dismally. “How in the world am I going to get out of this hole?”

The question could not be answered at once and Mark waited until he had got back some of his breath. Then he started to move off in the direction in which the split led.

He soon found that he was on an uncertain footing, for he had progressed less than a dozen feet when he began to sink into the pasty ooze of which the bottom of the opening was composed. The water was above his knees here and growing deeper.

“No use trying in that direction,” he told himself. “If there was an opening the water wouldn’t stand there like that. It’s a regular pocket and if I’m not careful I’ll plaster myself so fast that I’ll never get out.”

He thought to cry for help but then realized that his friends were a good distance off and that even if they heard him they would not know exactly how to reach the opening.

“I must help myself,” he murmured. “Surely I ought to be able to climb that wall of dirt somehow. Wonder if my pocketknife won’t help me?”

He brought forth the knife and dug the blade into the soil among the stones. But it would not hold and merely brought down more of the wall at his feet. Then, without warning a big mass of dirt came down, hurling him to the bottom of the pocket and covering him completely.

A big mass of dirt came down.