meanwhile frank had finished his repairing in the pilot-house and began to arrange for resuming the journey once more.

he kept a lookout for barney and the captain.

but for some inexplicable reason they did not seem to show up. soon twilight came.

“that is queer,” he muttered, “they are making a long trip. it is time that they should return.”

“dat am a fac’, sah,” averred pomp; “reckon dat wild i’ishman hab led dem away somewhere.”

frank fretted and fumed for a long time. certainly they had ought to be on hand by this time.

darkness came. then he made up his mind that something was wrong.

either something had befallen them or they were lost. he credited the latter assumption.

the air-ship was lit-up by the electric lamps and until a late hour watch was kept. then frank went into the pilot-house.

“we have got to go to their rescue,” he said.

“golly, marse frank!” exclaimed pomp, “how we know whar to look fo’ dem?”

“we must do the best we can,” said frank. “you stand by the searchlight, pomp, and shoot its rays everywhere through the mountains. i will manage the wheel.”

pomp proceeded to obey orders. the air-ship rose, and while frank sent it along the mountain side pomp operated the searchlight.

and here was where the two searchers got off the track. as fate had it, frank took the opposite direction, and, misled by an angle in the mountain, passed directly around to the other side.

here he followed the mountain wall in all directions. the result was that he kept moving further and further from the spot where barney and the captain were in hiding from the dreaded wild beasts.

all night long the young inventor kept up the futile quest.

when daylight came he and pomp were so thoroughly worn out that it was decided to abandon the quest for a few hours of needed rest.

accordingly the air-ship descended and rested upon a small shelf of rock jutting out from the mountain side. then frank cast himself upon his couch and fell asleep.

pomp remained on guard for a couple of hours. then he was relieved by frank. the darky turned in for much needed rest.

frank could not remain idle.

he sent the air-ship aloft and now saw his error of the night. he had sailed completely around the mountain peak and had been searching the wrong side of it all the while.

“egad!” he muttered, “it is no wonder that i did not find them. i hope they are yet safe. remaining out all night on these mountains is no joking matter.”

he hastened to drive the air-ship around to the opposite side of the peak again. as he did so the spectre hung for a moment over a deep chasm thousands of feet in depth.

involuntarily frank glanced down into the chasm, and then gave a great cry of astonishment and alarm.

far down in these awful depths he witnessed a thrilling scene.

a man hung over the fearful verge by the roots of a clinging vine.

it was knotted about his body, and he swung to and fro over the verge, liable at any moment to be precipitated to an awful death.

it required but a moment for frank to recognize the unfortunate man. it was barney o’shea.

the celt’s face was deadly pale and streaked with blood. his clothing was torn, and his appearance that of one who had experienced a hard battle.

as he saw the air-ship above him he waved his arm feebly. frank answered the signal.

then he allowed the spectre to sink down into the chasm. it was quickly close by the celt, and frank threw a noosed rope over the rail.

“barney,” he cried, “what does this mean? how came you in this position?”

“shure, sor, i had a fight with a panther,” replied the irishman. “we wint over the edge wid so much strugglin’, and i caught by luck in these vines. the crayter is dead at the bottom av this place.”

“you have been preserved by providence,” declared frank; “but where is the captain?”

“shure, sor, yez have the best av me there,” replied barney. “we siperated about midnight, an’ i’ve niver seen him since.”

in a few moments barney was drawn aboard the air-ship, and then he told his story.

it was a thrilling one.

it seemed that he had fallen asleep at the little camp-fire under the shelf or rock, where he and the captain had hoped to spend the night safely.

suddenly he was awakened by a terrific screech, and in trying to gain his feet a monster panther had pounced upon him.

he made a desperate fight with his knife, but the animal dragged him a long ways over the rough ground. then, as barney made a fresh battle with the beast, they had rolled over the precipice, with what result we already know.

this was all that the celt could tell. what had become of the captain he could not say. it was a puzzling matter.

however, frank proposed that they should return to the spot where the camp had been made and look for some sign of the missing mariner.

it was easy to follow the trail over the rocks which was marked with barney’s blood.

then they came upon the camp. it presented only a few burned fagots and a heap of ashes.

nicodemus was gone. he had left no visible trail.

this was strange enough.

pomp had now come on deck and assisted frank and barney. but not the slightest clew could be found.

there were various hypotheses to be advanced. it was possible that the captain, being suddenly awakened by the appearance of the panther, had taken fright and incontinently fled. that in the darkness he had lost his way and was somewhere in the region aimlessly wandering about.

it was not at all likely that he had been killed, devoured, or dragged away by any wild beast as had barney, else some trace would have been left behind.

a deeper mystery could hardly be imagined. but there was no time to lose.

the air-ship proceeded to skirt the mountain side, and every cranny and nook was explored.

but yet no sign of the lost captain was found. the day wore on and it began to look as if another night would be passed in the vicinity.

“shure it’s very quare,” declared barney. “i don’t see phwat he should go away for at all for whin the baste was afther me instid av himsilf.”

“it was not like the captain,” declared frank, “he would rather have paused to give you aid.”

“so i should think, sor. it’s moighty quare indade.”

but at the eleventh hour the mystery was solved. the air-ship dropped down the side of the peak a short distance, and this brought into view a long jagged spur of rock which shot out from the mountain wall and hung over an abyss thousands of feet deep.

and upon the very extremity of this there was seen the figure of a man. he waved his arms as the air-ship approached.

“by jupiter!” exclaimed frank, “that is beere. how did he get out there?”

indeed, this question might well be asked. it was not an easy one to answer.

it seemed almost incredible that a man could climb so far out on that awful pinnacle of rock. and once there, return was clearly impossible.

so it could be seen that the captain’s plight was a fearful one. but the air-ship sailed down upon him.

“heigho!” shouted frank. “what are you doing down there, captain?”

“that’s what i’ve been asking myself, mate,” replied the mariner, “give me a lift before i fall.”

“all right!”

frank lowered the same rope with which he had hauled barney up.

in a few moments the captain was safe on the air-ship’s deck.

his story was a remarkable one.

“how did i get there?” he exclaimed. “i couldn’t tell ye. i only know that i went to sleep in the little camp with barney. when i woke up i was hanging on out there.”

“somnambulism!” suggested frank.

“i reckon so; i am subject to that. sure to walk in my sleep if i go to bed with too much on my mind.”

“whew!” exclaimed frank. “you are hardly a safe man aboard an air-ship then.”

“i reckon not. but—how did you make out, barney?”

the captain was astonished when he heard the account of barney’s adventures. he had seen nothing of the panther, nor had he any recollection of anything until he came out of his sleep to find himself on the projecting spur of rock.

however, the affair was ended, and all were safe again aboard the spectre, which was a matter for congratulation; so frank at once proceeded to again direct the course of the air-ship.

down among the valleys now the air-ship sailed. the country, however, was wild and unsettled, though the scattered villages of a few indian natives were seen.

“it’s about time for us to get a look at the region about the transient lake,” declared nicodemus.

“can you see anything familiar about this region?” asked frank.

“yes,” replied the old mariner. “yonder is the range of hills where the paraguay river rises, if my eyesight does not fail me. on the other side of them we first found human beings.”

“well,” said frank reflectively, “we don’t want to go there.”

“no,” replied the captain; “steer west by south. i think that is our best course.”

the words were scarcely spoken when a great cry came from barney and pomp, who were aft. frank and nicodemus turned to behold an appalling spectacle.