All crowded around while Amos Henderson glanced at the mysterious message that had so curiously come to them. Some of the writing was very faint, but by the aid of a magnifying gla.s.s it was deciphered. Then, amid a deep silence the professor read the paper.

"Whoever may find this, take warning and do not seek to find the north pole. Danger lurks there. My name is Andre Christiansen, and I am a Dane, educated in America, who set out to find the pole. I discovered it but was taken into captivity by the fierce people who dwell around it. They determined to get rid of me. With a party I was sent away. I was to be killed and buried in the ice. Before they could kill me we were all attacked by polar bears. All the other men were killed and I was wounded.

As I write this I am dying. I write it with my blood and a piece of bone.

Send word to Denmark of my death, kind friend whoever you may be that finds this. If you reach this far in your search for the pole, be warned and go no farther. This is all I can write. I am nearly dead. I put the message in this copper cylinder which I brought along. I hope it will be found. Good-bye."

For a few moments after the professor ceased reading the strange message no one spoke. They were all thinking of the terrible fate that had befallen Andre Christiansen; to die all alone in that icy land, yet who, in the agony of death had thought to warn some explorer who might come after him.

"Poor fellow," murmured Amos Henderson. "He must have died soon after putting the message in the cylinder."

"And then the bears finished up their work by eating him and the men who wanted to kill him," said Andy. "They left only the bones."

"How long ago do you suppose that was written?" asked Jack.

"There is no telling," replied the professor. "But it must have been several years. I have read of all recent polar expeditions, and within the last twenty years there has been no one of this name to venture toward the pole. Besides the copper cap on the cylinder has become rusted on, and that would indicate the pa.s.sage of considerable time."

"I wonder if there are people at the pole?" came from Mark.

"We'll go and see!" exclaimed the professor.

"You don't mean to say you are going further north after what that message says?" asked Andy Sudds.

"Certainly; why not?"

"We may all be killed."

"We'll try not to have that happen," said the professor. "I am glad you boys found this. It is a valuable relic," and Amos Henderson put the message, the trinkets and the cylinder carefully away.

"I--I guess I won't go--" began Andy.

At that instant the airship gave a sudden tremble. Then the whole craft shivered. Next it began to rise in the air.

"Here we go!" cried the professor.

CHAPTER XIII

FORWARD ONCE MORE

The airship rose rapidly. Washington had continued to operate the gas machine until there was a sufficient quant.i.ty of vapor to overcome the contracting influence of the cold atmosphere.

"Forward once more!" cried the professor, hurrying to the engine room.

"This time we may reach the north pole!"

He and Washington soon started the motors, the dynamos and engines. The propeller revolved rapidly. The adventurers were under way again.

"Jack and Mark, go into the conning tower and steer!" called Mr.

Henderson from the engine room. "Take her up about half a mile, and send her straight north by the compa.s.s. I have to adjust some of the machinery."

Delighted at the prospect of running the airship, the two boys hurried forward. Mark went to the steering wheel, which was similar to the kind used on automobiles. The _Monarch_ was heading to the west, having no one to guide her, but Mark soon brought her around until her bow was poked directly for the north.

Under the guidance of the two boys, the airship rushed forward. They had become somewhat used to the queer feeling of being high up in the air, and now it did not seem wonderful to be sailing among the clouds, though two weeks before they would have laughed at the idea of such a thing.

Andy and the two farmers had, likewise, become a little indifferent to the strange sensations, and, aside from being careful not to go too near the rail of the ship when it was sailing aloft, they took no more precautions than as if they were on the deck of a steamboat.

For several hours the ship was kept on her course. The boys remained in the conning tower, gazing ahead. Not a single thing could be observed but a monotonous expanse of whiteness. Now and then they would run into a bank of clouds which obscured their vision as if there was a heavy fog.

"Look at the clock!" exclaimed Mark suddenly, pointing to the time-piece.

"What's the matter with it?" asked Jack.

"Can it be right?" went on Mark. "Surely it isn't nine o'clock, and the sun shining as brightly as if it was noon."

"It's nine o'clock at night!" exclaimed the professor, entering the steering tower in time to hear Mark's words.

"But it can't be," argued the boy. "Look how the sun is shining."

"You must realize where you are," was the reply. "We are so far north, my boy, that we are in the land of the midnight sun. From now on we will have daylight all the while. We are nearing the pole, where it is light six months of the year, and dark the other six. We are having summer here, now."

"I guess it don't feel much like summer outside," said Mark. "The thermometer indicates fifty below zero!"

"So it does," said Amos Henderson, glancing at the instrument which, though it was outside, could be read through the gla.s.s in the tower.

"Well, we may have struck a cold wave. Ordinarily we will not have much more than twenty below zero when the sun shines."

"That's cold enough for me," said Mark.

The professor announced that the airship's machinery was now in good shape. He said he expected to come to the end of the journey in about three days more, provided no accidents occurred, and there were no storms to delay the _Monarch_.

"I think we will divide the night into four watches," he said.

"Washington, Jack, Mark and I will take them in turn. During the day we will all be on duty, but from six in the morning to six at night we will stand watch and watch."

It was arranged that Jack should take the first period, the professor the second, Mark the third and Washington the fourth. As the first watch had pa.s.sed Jack was excused and the inventor said he would take charge of the ship. Then, as every one was tired from the happenings of the day, they all went to bed, excepting Amos Henderson, who entered the tower to steer the ship.

The engines, dynamos and motors ran without much attention save such as the pilot might give them occasionally, for he could leave the ship with the steering wheel fastened, a few minutes at a time, as there was no danger of collisions. So the _Monarch_ continued to race toward the north.

It was almost time for Mark's tour of duty to begin. The two boys, who were sleeping together, were in a deep slumber, when Washington ran in and shouted at the top of his voice:

"Wake up everybody! De perfessor is killed dead!"

Andy, Mark, Jack and the two helpers sat up in their bunks, rubbing their sleepy eyes and wondering what had happened.

"What's the matter?" asked Jack.

"Mr. Henderson is dead! He's in the engine room!"

"What killed him?" inquired Andy.