Straight toward the north, day and night, our destination compassled us after the fleeing flier upon which it had remained setsince I first attuned it after leaving the thern fortress.

Early in the second night we noticed the air becomingperceptibly colder, and from the distance we had comefrom the equator were assured that we were rapidlyapproaching the north arctic region.

My knowledge of the efforts that had been made by countlessexpeditions to explore that unknown land bade me to caution,for never had flier returned who had passed to any considerabledistance beyond the mighty ice-barrier that fringes the southernhem of the frigid zone.

What became of them none knew--only that they passed forever out ofthe sight of man into that grim and mysterious country of the pole.

The distance from the barrier to the pole was no more than a swiftflier should cover in a few hours, and so it was assumed that somefrightful catastrophe awaited those who reached the "forbidden land,"as it had come to be called by the Martians of the outer world.

Thus it was that I went more slowly as we approached the barrier,for it was my intention to move cautiously by day over the ice-packthat I might discover, before I had run into a trap, if there reallylay an inhabited country at the north pole, for there only could Iimagine a spot where Matai Shang might feel secure from John Carter,Prince of Helium.

We were flying at a snail's pace but a few feet above theground--literally feeling our way along through the darkness, forboth moons had set, and the night was black with the clouds thatare to be found only at Mars's two extremities.

Suddenly a towering wall of white rose directly in our path,and though I threw the helm hard over, and reversed our engine,I was too late to avoid collision. With a sickening crash westruck the high looming obstacle three-quarters on.

The flier reeled half over; the engine stopped; as one, thepatched buoyancy tanks burst, and we plunged, headforemost,to the ground twenty feet beneath.

Fortunately none of us was injured, and when we had disentangledourselves from the wreckage, and the lesser moon had burst againfrom below the horizon, we found that we were at the foot of amighty ice-barrier, from which outcropped great patches of thegranite hills which hold it from encroaching farther toward the south.

What fate! With the journey all but completed to be thuswrecked upon the wrong side of that precipitous and unscalable wallof rock and ice!

I looked at Thuvan Dihn. He but shook his head dejectedly.

The balance of the night we spent shivering in our inadequate sleepingsilks and furs upon the snow that lies at the foot of the ice-barrier.

With daylight my battered spirits regained something of theiraccustomed hopefulness, though I must admit that there was littleenough for them to feed upon.

"What shall we do?" asked Thuvan Dihn. "How may we pass thatwhich is impassable?"

"First we must disprove its impassability," I replied."Nor shall I admit that it is impassable before I havefollowed its entire circle and stand again upon this spot,defeated. The sooner we start, the better, for I see noother way, and it will take us more than a month to travelthe weary, frigid miles that lie before us."

For five days of cold and suffering and privation we traversedthe rough and frozen way which lies at the foot of the ice-barrier.Fierce, fur-bearing creatures attacked us by daylight and by dark.Never for a moment were we safe from the sudden charge of some hugedemon of the north.

The apt was our most consistent and dangerous foe.

It is a huge, white-furred creature with six limbs, four of which,short and heavy, carry it swiftly over the snow and ice;while the other two, growing forward from its shoulders on eitherside of its long, powerful neck, terminate in white, hairless hands,with which it seizes and holds its prey.

Its head and mouth are more similar in appearance to those ofa hippopotamus than to any other earthly animal, except that fromthe sides of the lower jawbone two mighty horns curve slightlydownward toward the front.

Its two huge eyes inspired my greatest curiosity. They extendin two vast, oval patches from the center of the top of the craniumdown either side of the head to below the roots of the horns, sothat these weapons really grow out from the lower part of the eyes,which are composed of several thousand ocelli each.

This eye structure seemed remarkable in a beast whose hauntswere upon a glaring field of ice and snow, and though I found uponminute examination of several that we killed that each ocellus isfurnished with its own lid, and that the animal can at will closeas many of the facets of his huge eyes as he chooses, yet I waspositive that nature had thus equipped him because much of his lifewas to be spent in dark, subterranean recesses.

Shortly after this we came upon the hugest apt that we had seen.The creature stood fully eight feet at the shoulder, and wasso sleek and clean and glossy that I could have sworn that he hadbut recently been groomed.

He stood head-on eyeing us as we approached him, for we had foundit a waste of time to attempt to escape the perpetual bestialrage which seems to possess these demon creatures, who rove thedismal north attacking every living thing that comes within thescope of their far-seeing eyes.

Even when their bellies are full and they can eat no more,they kill purely for the pleasure which they derive from taking life,and so when this particular apt failed to charge us, and insteadwheeled and trotted away as we neared him, I should have beengreatly surprised had I not chanced to glimpse the sheen of agolden collar about its neck.

Thuvan Dihn saw it, too, and it carried the same message ofhope to us both. Only man could have placed that collar there, andas no race of Martians of which we knew aught ever had attempted todomesticate the ferocious apt, he must belong to a people of thenorth of whose very existence we were ignorant--possibly to thefabled yellow men of Barsoom; that once powerful race which wassupposed to be extinct, though sometimes, by theorists,thought still to exist in the frozen north.

Simultaneously we started upon the trail of the great beast.Woola was quickly made to understand our desires, so that it wasunnecessary to attempt to keep in sight of the animal whose swiftflight over the rough ground soon put him beyond our vision.

For the better part of two hours the trail paralleled the barrier,and then suddenly turned toward it through the roughestand seemingly most impassable country I ever had beheld.

Enormous granite boulders blocked the way on every hand; deeprifts in the ice threatened to engulf us at the least misstep;and from the north a slight breeze wafted to our nostrils anunspeakable stench that almost choked us.

For another two hours we were occupied in traversing a fewhundred yards to the foot of the barrier.

Then, turning about the corner of a wall-like outcropping ofgranite, we came upon a smooth area of two or three acres beforethe base of the towering pile of ice and rock that had baffled usfor days, and before us beheld the dark and cavernous mouth of a cave.

From this repelling portal the horrid stench was emanating,and as Thuvan Dihn espied the place he halted with an exclamationof profound astonishment.

"By all my ancestors!" he ejaculated. "That I should havelived to witness the reality of the fabled Carrion Caves!If these indeed be they, we have found a way beyond the ice-barrier.

"The ancient chronicles of the first historians of Barsoom--soancient that we have for ages considered them mythology--record thepassing of the yellow men from the ravages of the green hordes thatoverran Barsoom as the drying up of the great oceans drove thedominant races from their strongholds.

"They tell of the wanderings of the remnants of this once powerful race,harassed at every step, until at last they found a way through theice-barrier of the north to a fertile valley at the pole.

"At the opening to the subterranean passage that led to theirhaven of refuge a mighty battle was fought in which the yellowmen were victorious, and within the caves that gave ingressto their new home they piled the bodies of the dead, both yellowand green, that the stench might warn away their enemies fromfurther pursuit.

"And ever since that long-gone day have the dead of this fabledland been carried to the Carrion Caves, that in death and decaythey might serve their country and warn away invading enemies.Here, too, is brought, so the fable runs, all the wastestuff of the nation--everything that is subject to rot, and thatcan add to the foul stench that assails our nostrils.

"And death lurks at every step among rotting dead, for herethe fierce apts lair, adding to the putrid accumulation with thefragments of their own prey which they cannot devour. It is ahorrid avenue to our goal, but it is the only one."

"You are sure, then, that we have found the way to the landof the yellow men?" I cried.

"As sure as may be," he replied; "having only ancient legendto support my belief. But see how closely, so far, each detailtallies with the world-old story of the hegira of the yellow race.Yes, I am sure that we have discovered the way to their ancienthiding place."

"If it be true, and let us pray that such may be the case," I said,"then here may we solve the mystery of the disappearance ofTardos Mors, Jeddak of Helium, and Mors Kajak, his son, for noother spot upon Barsoom has remained unexplored by the manyexpeditions and the countless spies that have been searching forthem for nearly two years. The last word that came from them wasthat they sought Carthoris, my own brave son, beyond the ice-barrier."

As we talked we had been approaching the entrance to the cave,and as we crossed the threshold I ceased to wonder that theancient green enemies of the yellow men had been halted by thehorrors of that awful way.

The bones of dead men lay man high upon the broad floor of thefirst cave, and over all was a putrid mush of decaying flesh,through which the apts had beaten a hideous trail toward theentrance to the second cave beyond.

The roof of this first apartment was low, like all that wetraversed subsequently, so that the foul odors were confinedand condensed to such an extent that they seemed to possesstangible substance. One was almost tempted to draw hisshort-sword and hew his way through in search of pure air beyond.

"Can man breathe this polluted air and live?"asked Thuvan Dihn, choking.

"Not for long, I imagine," I replied; "so let us make haste.I will go first, and you bring up the rear, with Woola between.Come," and with the words I dashed forward, across the fetidmass of putrefaction.

It was not until we had passed through seven caves of differentsizes and varying but little in the power and quality of theirstenches that we met with any physical opposition. Then, withinthe eighth cave, we came upon a lair of apts.

A full score of the mighty beasts were disposed about the chamber.Some were sleeping, while others tore at the fresh-killed carcassesof new-brought prey, or fought among themselves in their love-making.

Here in the dim light of their subterranean home the value oftheir great eyes was apparent, for these inner caves are shroudedin perpetual gloom that is but little less than utter darkness.

To attempt to pass through the midst of that fierce herdseemed, even to me, the height of folly, and so I proposed toThuvan Dihn that he return to the outer world with Woola, that thetwo might find their way to civilization and come again with asufficient force to overcome not only the apts, but any furtherobstacles that might lie between us and our goal.

"In the meantime," I continued, "I may discover some means ofwinning my way alone to the land of the yellow men, but if I amunsuccessful one life only will have been sacrificed. Should weall go on and perish, there will be none to guide a succoring partyto Dejah Thoris and your daughter."

"I shall not return and leave you here alone, John Carter,"replied Thuvan Dihn. "Whether you go on to victory or death,the Jeddak of Ptarth remains at your side. I have spoken."

I knew from his tone that it were useless to attempt to arguethe question, and so I compromised by sending Woola back with ahastily penned note enclosed in a small metal case and fastenedabout his neck. I commanded the faithful creature to seekCarthoris at Helium, and though half a world and countlessdangers lay between I knew that if the thing could be done Woolawould do it.

Equipped as he was by nature with marvelous speed and endurance,and with frightful ferocity that made him a match for any singleenemy of the way, his keen intelligence and wondrous instinctshould easily furnish all else that was needed for the successfulaccomplishment of his mission.

It was with evident reluctance that the great beast turned to leaveme in compliance with my command, and ere he had gone I could notresist the inclination to throw my arms about his great neck ina parting hug. He rubbed his cheek against mine in a final caress,and a moment later was speeding through the Carrion Caves towardthe outer world.

In my note to Carthoris I had given explicit directions for locatingthe Carrion Caves, impressing upon him the necessity for makingentrance to the country beyond through this avenue, and not to attemptunder any circumstances to cross the ice-barrier with a fleet.I told him that what lay beyond the eighth cave I could noteven guess; but I was sure that somewhere upon the other side of theice-barrier his mother lay in the power of Matai Shang, and thatpossibly his grandfather and great-grandfather as well, if they lived.

Further, I advised him to call upon Kulan Tith and the son ofThuvan Dihn for warriors and ships that the expedition might besufficiently strong to insure success at the first blow.

"And," I concluded, "if there be time bring Tars Tarkas with you,for if I live until you reach me I can think of few greater pleasuresthan to fight once more, shoulder to shoulder, with my old friend."

When Woola had left us Thuvan Dihn and I, hiding in the seventh cave,discussed and discarded many plans for crossing the eighth chamber.From where we stood we saw that the fighting among the apts wasgrowing less, and that many that had been feeding had ceased andlain down to sleep.

Presently it became apparent that in a short time all the ferociousmonsters might be peacefully slumbering, and thus a hazardousopportunity be presented to us to cross through their lair.

One by one the remaining brutes stretched themselves upon thebubbling decomposition that covered the mass of bones uponthe floor of their den, until but a single apt remained awake.This huge fellow roamed restlessly about, nosing among hiscompanion and the abhorrent litter of the cave.

Occasionally he would stop to peer intently toward firstone of the exits from the chamber and then the other.His whole demeanor was as of one who acts as sentry.

We were at last forced to the belief that he would not sleepwhile the other occupants of the lair slept, and so cast about inour minds for some scheme whereby we might trick him. Finally Isuggested a plan to Thuvan Dihn, and as it seemed as good as anythat we had discussed we decided to put it to the test.

To this end Thuvan Dihn placed himself close against thecave's wall, beside the entrance to the eighth chamber, while Ideliberately showed myself to the guardian apt as he looked towardour retreat. Then I sprang to the opposite side of the entrance,flattening my body close to the wall.

Without a sound the great beast moved rapidly toward theseventh cave to see what manner of intruder had thus rashlypenetrated so far within the precincts of his habitation.

As he poked his head through the narrow aperture that connectsthe two caves a heavy long-sword was awaiting him upon either hand,and before he had an opportunity to emit even a single growl hissevered head rolled at our feet.

Quickly we glanced into the eighth chamber--not an apt had moved.Crawling over the carcass of the huge beast that blocked thedoorway Thuvan Dihn and I cautiously entered the forbiddingand dangerous den.

Like snails we wound our silent and careful way among thehuge, recumbent forms. The only sound above our breathing wasthe sucking noise of our feet as we lifted them from the ooze ofdecaying flesh through which we crept.

Halfway across the chamber and one of the mighty beastsdirectly before me moved restlessly at the very instant that myfoot was poised above his head, over which I must step.

Breathlessly I waited, balancing upon one foot, for I did notdare move a muscle. In my right hand was my keen short-sword,the point hovering an inch above the thick fur beneath whichbeat the savage heart.

Finally the apt relaxed, sighing, as with the passing of a baddream, and resumed the regular respiration of deep slumber.I planted my raised foot beyond the fierce head and an instantlater had stepped over the beast.

Thuvan Dihn followed directly after me, and another momentfound us at the further door, undetected.

The Carrion Caves consist of a series of twenty-sevenconnecting chambers, and present the appearance of having beeneroded by running water in some far-gone age when a mighty riverfound its way to the south through this single breach in thebarrier of rock and ice that hems the country of the pole.

Thuvan Dihn and I traversed the remaining nineteen cavernswithout adventure or mishap.

We were afterward to learn that but once a month is it possibleto find all the apts of the Carrion Caves in a single chamber.

At other times they roam singly or in pairs in and out of the caves,so that it would have been practically impossible for two men tohave passed through the entire twenty-seven chambers withoutencountering an apt in nearly every one of them. Once a monththey sleep for a full day, and it was our good fortune to stumbleby accident upon one of these occasions.

Beyond the last cave we emerged into a desolate country ofsnow and ice, but found a well-marked trail leading north.The way was boulder-strewn, as had been that south of the barrier,so that we could see but a short distance ahead of us at any time.

After a couple of hours we passed round a huge boulder to cometo a steep declivity leading down into a valley.

Directly before us we saw a half dozen men--fierce, black-beardedfellows, with skins the color of a ripe lemon.

"The yellow men of Barsoom!" ejaculated Thuvan Dihn, as thougheven now that he saw them he found it scarce possible to believethat the very race we expected to find hidden in this remote andinaccessible land did really exist.

We withdrew behind an adjacent boulder to watch the actions of thelittle party, which stood huddled at the foot of another huge rock,their backs toward us.

One of them was peering round the edge of the granite mass asthough watching one who approached from the opposite side.

Presently the object of his scrutiny came within the rangeof my vision and I saw that it was another yellow man. Allwere clothed in magnificent furs--the six in the black and yellowstriped hide of the orluk, while he who approached alone wasresplendent in the pure white skin of an apt.

The yellow men were armed with two swords, and a short javelinwas slung across the back of each, while from their left arms hungcuplike shields no larger than a dinner plate, the concave sides ofwhich turned outward toward an antagonist.

They seemed puny and futile implements of safety against aneven ordinary swordsman, but I was later to see the purpose of themand with what wondrous dexterity the yellow men manipulate them.

One of the swords which each of the warriors carried caught myimmediate attention. I call it a sword, but really it was a sharp-edged blade with a complete hook at the far end.

The other sword was of about the same length as the hookedinstrument, and somewhere between that of my long-sword and myshort-sword. It was straight and two-edged. In addition to theweapons I have ennumerated each man carried a dagger in his harness.

As the white-furred one approached, the six grasped theirswords more firmly--the hooked instrument in the left hand, thestraight sword in the right, while above the left wrist the smallshield was held rigid upon a metal bracelet.

As the lone warrior came opposite them the six rushed out uponhim with fiendish yells that resembled nothing more closely thanthe savage war cry of the Apaches of the South-west.

Instantly the attacked drew both his swords, and as the six fellupon him I witnessed as pretty fighting as one might care to see.

With their sharp hooks the combatants attempted to take hold of anadversary, but like lightning the cupshaped shield would springbefore the darting weapon and into its hollow the hook would plunge.

Once the lone warrior caught an antagonist in the side withhis hook, and drawing him close ran his sword through him.

But the odds were too unequal, and, though he who fought alonewas by far the best and bravest of them all, I saw that it wasbut a question of time before the remaining five would find anopening through his marvelous guard and bring him down.

Now my sympathies have ever been with the weaker side of an argument,and though I knew nothing of the cause of the trouble I could notstand idly by and see a brave man butchered by superior numbers.

As a matter of fact I presume I gave little attention toseeking an excuse, for I love a good fight too well to need anyother reason for joining in when one is afoot.

So it was that before Thuvan Dihn knew what I was about he sawme standing by the side of the white-clad yellow man, battling likemad with his five adversaries.