NEVER in their lives had the explorers witnessed anything like the terrible onslaught that followed. The violent, ruthless wind dashed the monoplane about dangerously, threatening at every moment to tear it to pieces. It was but a frail, man-made machine when caught in those forces of nature.

Karl’s ability as a pilot promised to be tested to the utmost. If he could keep the ship straight it would be nothing short of miraculous. The less skillful aviator would send his craft dashing down to the foamy water below. But Karl was by no means a novice. He had had wide experience in piloting passenger monoplanes on schedule across the United States.

“Sit tight!” he called through the telephone, suspecting that his friends were frightened. “We’ll get out some way—I hope.”

Every gust of wind tossed the ’plane about hazardously. It seemed that a plunge would be inevitable.

In the cockpit Karl Sutman was determined to bring his friends and himself safely through the danger. With nerves of steel, he hung on desperately to the stick and the rudder bar, keeping his keen eyes glued to the horizon.

It was indeed a race between life and death, as the staunch ’plane was swung about at the mercy of the storm. Many times before had the machine proved itself capable of withstanding the assault of the elements, but this was the supreme test. If it could weather this, it would indeed be a strong machine.

Inside the cabin, the youths and the naturalists were pale with an awful fear that this would be the end. They could not conceive of passing safely through such a hurricane as this. They were only too aware that many an aviator had gone to his doom in a tropical storm.

Now, to add to the terrible scene, a heavy rain began to fall, coming in great gusts with the wind. It pattered ominously on the wings, bearing the monoplane down with the added weight.

“Oh!” groaned Joe, almost giving up in despair. “I suppose the worst is yet to come.”

“Cheer up,” said Mr. Holton, who was inclined to be hopeful, as he noticed that the wind was blowing more evenly. “It can’t last so very much longer.”

Despite this expression of optimism, the hurricane continued at full force, although a bit smoother than at first. Now the wind, instead of coming in great gusts, blew steadily.

This made it slightly easier to handle the ’plane and took some of the severe strain from Karl. But he still was forced to use all his energy in keeping the craft at as even keel as possible.

All knew that a tropical storm was usually over a wider area than one in the temperate zone. It was this that had made it impossible for Karl to steer the ’plane to safety before the gale struck.

Only gradually did the monoplane pass through the clouds, which extended many miles in every direction.

Finally, when a clear sky again became visible, the explorers uttered cries of relief. They had at last escaped what seemed like certain disaster.

Bob moved over to the transmitter.

“You were wonderful, Karl, old boy!” he praised. “If most anyone else had been in your seat, we wouldn’t be in the air now.”

“Oh, there are plenty others that could have done it,” the aviator returned, his voice sounding a bit nervous. “I just saw that I had to get out some way and did everything I could.”

The storm had served in no small measure to heighten the explorers’ admiration for their pilot. If the latter could safely guide them through such a display of the elements, he could be depended upon for almost any crisis.

The brilliant sun was now rapidly showing itself in full view, casting a sparkling reflection on the ocean. All evidences of the storm were covered up, even the heavy foam caps having disappeared. It was as though nature were repenting of her arduous activities.

As they flew on, the explorers had a strong hope that the weather would remain calm during the remainder of their journey. They were nearing land now, and they wished to finish the trip in a cloudless sky.

At last, when they were becoming weary from seeing nothing but boundless water, they suddenly caught sight of a dim shape that covered the whole of the horizon. That shape became larger and more plain, until it took on the form of land.

“Hurrah!” cried Bob joyfully. “South America at last!”

“I believe you’re right,” came from his father. “It——”

“Announcing our arrival at the great continent of South America!” Karl’s voice, coming loudly through the telephone, broke off with a laugh.

As they came nearer, the aviator guided the machine to a lower altitude, although still high enough to see many miles in every direction.

But it was a long while before they could make out plainly the details of the coast. Fog made it necessary to fly very near in order to see anything distinctly.

“I believe I can make out the Andes,” said Joe, gazing out at the distant horizon.

“Don’t be sure,” laughed Mr. Wallace. “Those mountains are a long way off.”

Before long they had passed the coast and headed over the land, almost directly above the Magdalena River, whose course they could easily make out.

For the most part, the country they were flying over was rugged and uncultivated, but there were occasional towns and villages that dotted the valleys and clearings.

“BogotÁ is the first large city we’ll see,” announced Karl. “We ought to get there by tomorrow noon.”

“Where will we spend tonight?” asked Joe, as he noticed that darkness was not far off.

“Suppose we land before long and put up our tent,” suggested Mr. Holton, stepping up to the telephone transmitter.

“I was just getting ready to do that,” Karl answered him, and then added: “Here’s a good spot now.”

There was a wide, level field directly below them. Karl sent the monoplane off to the west and then headed it back and downward.

A perfect three-point landing was made in the tall grass, the ship coming to a stop at the very edge of a frowning jungle.

Once more the explorers got out and stretched their legs.

Bob and Joe had just started over to the jungle when they heard something that made them turn about quickly.

“There’s a leak in the gas tank,” Karl said ominously, “and the gas is almost gone. We landed just in time.”