"he'll be killed!" shouted jack.

"he's a goner!" yelled washington, looking up from the engine room window.

the old professor groaned and shut his eyes. he did not want to see the boy fall.

bill and tom, with old andy sudds, had been watching mark at his perilous task, standing directly beneath him. andy was the closer. he leaned quickly backward when he saw what had happened.

mark's body, turning over in its descent, was at the ship's side. out shot the hands of the old hunter. his fingers were curved like the talons of an eagle. the long arms seemed to reach a great distance, and then, just as it seemed that mark would plunge downward to his death, andy grasped and held him.

"there!" exclaimed the hunter. "that was a close call, my boy!"

mark did not answer. the fearful danger he had been saved from had so frightened him that he became partially unconscious.

"is he dead?" faltered jack.

"he has only fainted," answered amos henderson. "i'll soon bring him around."

the inventor hurried into the cabin and came out with some liquid in a glass. this he placed to mark's lips and soon the color came back into the pale cheeks.

"what happened? where am i?" asked the boy, sitting up and looking around.

"you're all right," answered andy. "it was a close call though. i reckon you won't want to mend any more airships right away."

"i remember now," went on mark, who had been dazed by the suddenness of it all. "i fell, didn't i?"

"yes, and andy caught you," put in jack. "he was just in time."

mark said nothing, but the fervor with which he shook the old hunter by the hand showed how deep his feeling was.

in a little while the fright and excitement caused by the accident had passed over. the ship now rode evenly and neither rose nor fell, in consequence of the gas supply in the bag remaining the same, there being no leak. the patch mark had put on fitted so closely that there was not the least escape of gas now.

"well, we might as well start ahead," said amos henderson, at length. "we have had excitement enough in this neighborhood, and maybe we'll be better off if we go forward."

accordingly he went to the conning tower, set the propeller in motion, and soon the monarch was moving northward at great speed. with his eyes on the compass in front of him the captain held the ship on her course.

they were about half a mile above the ground now, the captain having allowed the monarch to settle. they could see that they were passing over a populated part of the country.

"come up here!" yelled captain henderson to the boys from the steering tower. "i'll explain a few things to you."

willingly enough the boys joined him. he was busy making a calculation of figures on a piece of paper. the steering wheel was lashed and the compass pointed to indicate that the ship was rushing due north.

"we're making satisfying progress," said the professor. "at this rate we will not be long on the journey."

"how fast are we moving?" asked jack.

"about fifty miles an hour," replied the inventor. "that is 1,200 miles a day, counting that we run day and night at this speed. but we will hardly do that, not that we could not, for there will be no dangers of collisions up here. i think we have the air all to ourselves.

"but there will be contrary winds, and we may be blown off our course. that is the only disadvantage an airship is under. it can't sail against the wind like a ship on the water. still, we have many advantages. now i figure that we can count on an average of at least twenty-five miles an hour all day long and part of the night.

"we started from about the middle of new york state, and to the north pole would be about 3,000 miles. we ought to make the distance in about five days, or say a week, to be on the safe side. we will move as fast as we can, from now on, though, especially during the daylight."

the professor turned some wheels and levers and the speed of the airship increased a little. it was kept at about the same height.

the sun was beginning to descend in the west, for it was getting late in the afternoon. down below, on the earth, the landscape had changed from that of cities and towns to a stretch of dense woods.

"must be near supper time," observed mark.

"your fright didn't deprive you of your appetite, then?" asked amos

henderson.

"not a bit," replied the boy.

in a few minutes tom and bill were preparing a meal of the condensed foods, cooked on the electric stove. everyone voted the victuals excellent. then, as night settled down, the bunks were made up and the boys, together with the two farm hands, were glad to seek some rest, for the day had been an exciting one. washington and the professor agreed to divide the night into two watches, as they were not familiar enough with the workings of the ship to dare to leave it unguarded. the machinery might need attention any moment.

the boys and their companions were soon asleep, and no thoughts of their strange position, that of slumbering on an airship high in the atmosphere, disturbed their dreams.

the last thing jack wondered was whether the passing of the monarch would not be taken by people on the earth for the flight of some giant comet, as it sailed aloft, all lighted up. but he was too tired to pursue this speculation long.

morning dawned without anything unusual having occurred. the ship had been kept going at a slow speed all night, and no accidents happened. breakfast was served, and then each of the crew took up his duties.

the professor, having made a careful examination of the ship to see that everything was in order, showed jack and mark how to steer the craft, and how to start, stop, raise and lower it from the conning tower or the engine room.

then he let them practice a bit, and two more delighted boys there never was, as they sent the craft ahead up or down, starting and stopping her with a few turns of a wheel or lever.

"you may want to know how to run her some day in an emergency," said

amos henderson. "no telling what will happen."

"we hope nothing will," spoke jack.

"there's no telling," prophesied the inventor.

for several days the ship moved ahead at moderate speed. the machinery, excepting for some minor accidents, worked smoothly. the gas bag did not leak, which was the accident most dreaded, and it was not necessary to run the gas generator, which proved a saving of the valuable chemical from which the lifting-vapor was produced.

now and then, when in need of water, the craft was lowered to the earth in a secluded spot near a stream or lake, and the tanks were filled for drinking and washing purposes. but so far, from the time of the hasty flight, no one on the earth had spoken to the voyagers. nor, so far as was known, had their presence been noted, though the black speck in the sky might have furnished plenty of talk all over the country for those who observed it. the weather was pleasant, but it was noticed that it was constantly growing colder.

one morning jack, who was the first up, stuck his head out of the cabin door before he had finished dressing. he quickly popped back again.

"whew!" he exclaimed. "colder than greenland!"

"what's that about greenland?" asked the professor, who had just awakened.

"it's awful cold outside," said jack, shivering from the remembrance.

without a word the professor, wrapping a dressing-gown about him, hurried to the engine room, where several thermometers were kept. one was outside, and could be read through a glass side.

"no wonder you felt cold," he said to jack, when he returned. "it's ten degrees below zero!"

the boys hurried to complete their dressing. the professor did likewise, as he was anxious to take some observations.

"get out the fur garments," he said. "we must take no more chances now. it will become colder rapidly, and ordinary clothes will be of no protection."

the boys and the professor donned heavy fur coats, with immense gloves and caps that covered all of their faces but the eyes. then they went outside. jack was the first to look over the side of the ship. as he did so he uttered a cry of astonishment.

down below, about three-quarters of a mile, was a great white, snowy waste. giant mountains of ice were heaped on every side. it was a cold, frosty silent world that the monarch was flying over. they had reached the frozen north! they were at the beginning of the entrance to the land of the pole!