"i'm not surprised that the thermometer is down below zero," remarked

jack. "there's enough ice under us to supply the whole united states."

"it is getting colder!" exclaimed the inventor as he glanced at an instrument near him. "it is fifteen below zero now!"

in truth the monarch was far to the north. she had gone faster than the inventor calculated. a glance downward showed that all traces of civilization had been left behind.

there was nothing to be seen but snow and ice, ice and snow, piled in fantastic heaps,—mountains, ridges, hills and valleys.

the professor hastily made a few calculations.

"i believe we are somewhere over greenland or baffin bay, but whether we are over the land or sea i cannot tell. at any rate we are still going north," and he glanced at the compass.

they were about to retrace their steps to the dining cabin, when there was a sudden settling of the monarch. it seemed to be plunging downward.

"what's the matter?" cried jack.

the inventor hurried to the engine room. a glance at the registering needle of the instrument for telling the height attained, showed that the ship was sinking fifty feet a minute.

"some conglomerous contraption has disproportionated herself," cried

washington. "what shall i do, perfessor?"

"start the gas generator at full speed!" cried the inventor. "heat the vapor before it goes to the bag! the cold has contracted the gas in the holder above so that it will no longer support us! work quick, washington!"

washington sprang to set the gas machine in operation. he seemed to be having trouble with it.

"she won't work!" he called. "she's busted!"

faster and faster the airship continued to sink. the inventor hurried to washington's help, but it seemed that nothing could be done. on board the monarch there was deadly fear in every heart.

"i can't keep her afloat!" the professor groaned.

down and down went the craft. the inventor and washington were working furiously. the boys, old andy and tom and bill hurried to the engine room.

then came a sudden jolt. the airship had struck the ice!

"shut off the engines!" cried the professor. "stop everything or we'll go to smash! we must set to work to repair the gas machine and raise the ship."

the monarch had settled down on a vast ice plane. so gently had the ship sunk through the air that she had suffered no injury. she rested on an even keel and there was still enough lifting power in the gas contained in the bag to keep that afloat, so that the vapor holder tugged gently at the confining meshes of the net.

"ma goodness sakes alive!" cried washington as soon as he had poked his head out of the warm engine room. "de atmospheric conditions am such dat dey is conducive to de utmost congestion of mah circulatory systemation!"

"i suppose you mean it is too cold for your blood," spoke the inventor, with a smile.

"yo' has conducted mah meanin' to de utmost circumspection, perfessor," was the answer.

"you'd better get out a suit of furs," suggested the captain, for washington had not yet donned these garments. the colored man ran back into the cabin, got out the heaviest set he could find, and put it on.

the professor and the boys, together with the two helpers, were clothed to withstand the rigors of the arctic regions. in a little while washington was warmly dressed. then the professor led the way over the rail and down on the ice.

"are we on land or sea?" asked jack.

"it's hard to say, but i think we are on land," replied amos henderson. "however, it doesn't make much difference. we are pretty far north. the thing to do is to get the airship in shape as quickly as possible."

"can we help?" asked mark.

"i hardly think so," answered the old inventor. "washington and i understand every piece of machinery. if we need any help we will call on you. in the meanwhile you may take a look around if you wish."

"i'd like to stretch my legs a bit," spoke up old andy. "i ain't used to stayin' cramped up in a ship like i have been. i'd like to see some of that big game you talked about, professor."

"take your gun along, and you may spot a polar bear or a walrus," suggested mr. henderson. "some fresh bear steak would not go badly at all."

delighted at the prospect at getting a shot andy hastened after his gun. then after a hasty breakfast, with the two boys and the two helpers as companions, all warmly wrapped in furs, the hunter set forth across the fields of ice and snow.

it was a strange experience for all of them. there was not a sign of life to be seen. on every side there was nothing but the cold whiteness—a coldness and a whiteness that was like death itself. they walked on for more than a mile, and saw nothing but the desolate waste.

"there's something!" called jack in a hoarse whisper, coming to a halt and pointing to a small hill of ice in the distance.

"it's a polar bear!" yelled mark. "he's right behind the ice!"

"there are two of 'em!" cried bill. "this is no place for me! come on,

tom!"

"hold still! let me get a shot!" pleaded the old hunter.

he could see the two animals plainly, now that his eyes had become used to the difference between their shaggy coats and the surrounding snow and ice. andy kneeled down and took careful aim. a shot rang out, and one of the bears toppled over.

"good shot!" cried jack.

once more the hunter pulled the trigger. a dull click was the only response. andy quickly cocked the gun again, thinking it had missed fire. again the hammer fell with only a click. the hunter quickly threw open the magazine.

"the chamber is empty!" he cried. "i have fired my last shot!"

"and there comes the bear!" yelled mark. "he's in a fit of rage!"

the fierce beast, in anger at the sight of his enemies, was coming toward the men and boys at top speed. on the first alarm bill and tom had turned to flee. andy, swinging his gun by the muzzle, and loosening a long hunting knife in his belt, awaited the bear's onslaught. mark and jack were too surprised to run, and stood their ground, not knowing what to do.

"run away!" shouted andy. "i'll tackle the beast! i'm not afraid!"

"we're not going to leave you!" yelled jack. "i have a revolver!"

quickly he drew out the small weapon, a present from the inventor. taking hasty aim he fired several shots, but his aim was poor. one bullet struck the bear on the nose, and, instead of stopping the beast, only made him the more angry.

the brute was now but fifty feet away and coming on at a rapid pace over the uneven lumps of ice and snow.

"run, i tell you!" called andy. "do you boys want to be killed?"

he aimed a furious stroke at the bear, but as he did so his foot slipped and he came down heavily on the ice. mark and jack uttered cries of terror and fright.

with blood dripping from his wounds, foam falling from his red jaws, and with every appearance of rage, the maddened beast rushed on the old hunter.

"he'll be killed!" yelled mark.

"if i only had a gun!" groaned jack.

andy rolled to one side. as he did so he uttered a loud cry, and then, to the astonishment of the boys, he disappeared from sight as if the frozen earth had opened and swallowed him up. at the same time the bear, that was just about to cast himself down on the fallen hunter, seemed to drop down through some hole into the earth.

for an instant jack and mark looked at each other with fear in their eyes.

"what has happened?" inquired mark, in an awestruck voice.

"i don't know," answered jack. "but look! there are spots of blood over there. that is where the bear was!"

the boys ran forward. as they did so their feet seemed to slip from under them. down and down they felt themselves going. faster and faster they slipped. they gazed with frightened eyes about them and saw they were on some giant slide of ice, that led into unknown regions.

"where are we going?" gasped mark.

"i don't know!" yelled back jack. "at any rate we're getting a good coast!" he could joke even in the face of danger.

with a jolt the two boys came to the end of their sudden journey. for a moment they were so startled and shaken up that they could hardly see. then, as their senses came back, they gazed around.

there were white glistening walls of ice on every side. above glittered a tiny patch of light, showing where the blue sky was.

"where are we?" asked mark.

"you're with me an' the bear!" exclaimed a voice.

the boys started. they saw, lying near them, old andy. at his feet was the polar bear, dead, with the hunter's knife sticking in his heart.

"and what place is this?" asked jack.

"it appears to me like a big ice cave," answered the hunter.

"yes, and we're lost in it," spoke up jack, and gave something of a shudder.

"that's right, my boy," answered andy sudds.