left to himself, with only the rather silent gang of peruvian indians as company, tom swift looked about him. there was not much active work to be done, only to see that the indians filled the dump cars evenly full, so none of the broken rock would spill over the side and litter the tramway. then, too, he had to keep the indians up to the mark working, for these men were no different from any other, and they were just as inclined to "loaf on the job" when the eye of the "boss" was turned away.

they did not talk much, murmuring among themselves now and then, and little of what they said was intelligible to tom. but he knew enough of the language to give them orders, the main one of which was:

"hurry up!"

now, having seen to it that the gang of which he was in temporary charge was busily engaged, tom had a chance to look about him. the tunnel was not new to him. much of his time in the past month had been spent in its black depths, illuminated, more or less, by the string of incandescent lights.

"what i want to find," mused tom, as he walked to and fro, "is the place where those indians disappeared. for i'm positive they got away through some hole in this tunnel. they never came out the main entrance."

tom held to this view in spite of the fact that nearly every one else believed the contrary—that the men had left by the tunnel mouth, near which tom happened to be alone at the time.

now, left to himself, with merely nominal duties, and so disguised that none of the workmen would know him for the trim young inventor who oversaw the preparing of the blast charges, tom swift walked to and fro, looking for some carefully hidden passage or shaft by means of which the men had got away.

"for it must be well hidden to have escaped observation so long," tom decided. "and it must be a natural shaft, or hole, for we are boring into native rock, and it isn't likely that these indians ever tried to make a tunnel here. there must be some natural fissure communicating with the outside of the mountain, in a place where no one would see the men coming out."

but though tom believed this it was another matter to demonstrate his belief. in the intervals of seeing that the natives properly loaded the dump cars, and removed as much of the debris as possible, tom looked carefully along the walls and roof of the tunnel thus far excavated.

there were cracks and fissures, it is true, but they were all superficial ones, as tom ascertained by poking a long pole up into them.

"no getting out that way," he said, as he met with failure after failure.

once, while thus engaged, he saw serato, the indian foreman looking narrowly at him, and serato said something in his own language which tom could not understand. but just then along came tim sullivan, who, grasping the situation, exclaimed:

"thot's all roight, now, serri, me lad!" for thus he contracted the indian's name. "thot's a new helper i have, a broth of a bye, an' yez kin kape yer hands off him. he's takin' orders from me!"

"um!" grunted the indian. "wha for he fish in tunnel roof?" for tom's pole was one like those the indians used when, on off days, they emulated izaak walton.

"fishin' is it!" exclaimed tim. "begorra 'tis flyin' fish he's after i'm thinkin'. lave him alone though, serri! i'm his boss!"

"um!" grunted the indian again, as he moved off into the farther darkness.

"be careful, tom," whispered the irishman, when the native had gone. "these black imps is mighty suspicious. maybe thot fellah had a hand in th' disappearances hisself."

"maybe," admitted tom. "he may get a percentage on all new hands that are hired."

tom kept on with his search, always hoping he might find some hidden means of getting out of the tunnel. but as the days went by, and he discovered nothing, he began to despair.

"the queer thing about it," mused tom, "is what has become of the ten men. even if they did find some secret means of leaving, what has become of them? they couldn't completely disappear, and they have families and relatives that would make some sort of fuss if they were out of sight completely this long. i wonder if any inquiries have been made about them?"

when tom came off duty he asked the titus brothers whether or not any of the relatives of the missing men had come to seek news about them. none had.

"then," said tom, "you can depend on it the men are all right, and their relatives know it. i wonder how it would do to make inquiries at that end? question some of the relatives."

"bless my hat band!" exclaimed mr. damon, who was at the conference. "i never thought of that. i'll do it for you."

the odd man had gotten his quinine gathering business well under way now, and he had some spare time. so, with an interpreter who could be trusted, he went to the native village whence had come nearly all of the ten missing men. but though mr. damon found some of their relatives, the latter, with shrugs of their shoulders, declared they had seen nothing of the ones sought.

"and they didn't seem to worry much, either," reported mr. damon.

"then we can depend on it," remarked tom, "that the men are all right and their relatives know it. there's some conspiracy here."

so it seemed. but who was at the bottom of it?

"i can't figure out where blakeson & grinder come in," said job titus. "they would have an object in crippling us, but they seem to be working from the financial end, trying to make us fail there. i haven't seen any of their sneaking agents around here lately, and as for waddington he seems to have stayed up north."

tom resumed his vigil in the tunnel, poking here and there, but with little success. his week was about up, and he would soon have to resume his character as powder expert, for the debris was nearly all cleaned up, and another blast would have to be fired shortly.

"well, i'm stumped!" tom admitted, the day when he was to come on duty for the last time as a pretended foreman. "i've hunted all over, and i can't find any secret passage."

it was warm in the tunnel, and tom, having seen one train of the dump cars loaded, sat down to rest on an elevated ledge of rock, where he had made a sort of easy chair for himself, with empty cement bags for cushions.

the heat, his weariness and the monotonous clank-clank of a water pump near by, and the equally monotonous thump of the lumps of rocks in the cars made tom drowsy. almost before he knew it he was asleep.

what suddenly awakened him he could not tell. perhaps it was some influence on the brain cells, as when a vivid dream causes us to start up from slumber, or it may have been a voice. for certainly tom heard a voice, he declared afterward.

as he roused up he found himself staring at the rocky wall of the tunnel. and yet the wall seemed to have an opening in it and in the opening, as if it were in the frame of a picture, appeared the face tom had seen at his library the day job titus called on him—the face of waddington!

tom sat up so quickly that he hit his head sharply on a projecting rock spur, and, for the moment he "saw stars." and with the appearance of these twinkling points of light the face of waddington seemed to fade away, as might a vision in a dream.

"bless my salt mackerel, as mr. damon would say!" cried tom. "what have i discovered?"

he rubbed his head where he had struck it, and then passed his hand before his eyes, to make sure he was awake. but the vision, if vision it was, had vanished, and he saw only the bare rock wall. however, the echo of the voice remained in his ears, and, looking down toward the tunnel floor tom saw serato, the indian foreman.

"were you speaking to me?" asked tom, for the man understood and spoke english fairly well.

"no, sar. i not know you there!" and the foreman seemed startled at seeing tom. clearly he was in a fright.

"you were speaking!" insisted tom.

"no, sar!" the man shook his head.

"to some one up there!" went on the young inventor, waving his hand toward the spot where he had seen the face in the rock.

"me speak to roof? no, sar!" serato laughed.

tom did not know what to believe.

"you hear me tell um lazy man to much hurry," the indian went on. "me not know you sleep there, sar!"

"oh, all right," tom said, recollecting that he must keep up his disguise. "maybe i was dreaming."

"yes, sar," and the foreman hurried on, with a backward glance over his shoulder.

"now was i dreaming or not?" thought tom. "i'm going to have a look at that place though, where i saw waddington's face. or did i imagine it?"

he got a long pole and a powerful flash lamp, and when he had a chance, unobserved, he poked around in the vicinity where he had seen the face.

but there was only solid rock.

"it must have been a dream," tom concluded. "i've been thinking too much about this business. i'll have to give up. i can't solve the mystery of the missing men."

the next day, much disappointed, he resumed his own character as explosive expert, and prepared for another blast. the net result of his watch was that he became suspicious of serato, and so informed the titus brothers.

"oh, but you're mistaken," said job. "we have had him for years, on other contracts in peru, and we trust him."

"well, i don't," tom said, but he had to let it go at that.

another blast was set off, but it was not very successful.

"the rock seems to be getting harder the farther in we go," commented walter titus. "we're not up to where we ought to be."

"i'll have to look into it," answered tom. "i may have to change the powder mixture. guess i'll go up the mountain a way, and see if there are any outcroppings of rock there that would give me an idea of what lies underneath."

accordingly, while the men in the tunnel were clearing away the rock loosened by the blast, tom, one day, taking his electric rifle with him, went up the mountain under which the big bore ran.

he located, by computation, the spot beneath which the end of the tunnel then was, and began collecting samples of the outcropping ledge. he wanted to analyze these pieces of stone later. koku was with him, and, giving the giant a bag of stones to carry, tom walked on rather idly.

it was a wild and desolate region in which he found himself on the side of the mountain. beyond him stretched towering and snow-clad peaks, and high in the air were small specks, which he knew to be condors, watching with their eager eyes for their offal food.

as tom and koku made their way along the mountain trail they came unexpectedly upon an indian workman who was gathering herbs and bark, an industry by which many of the natives added to their scanty livelihood. the woman was familiar with the appearance of the white men, and nodded in friendly fashion.

tom passed on, thinking of many things, when he was suddenly startled by a scream from the woman. it was a scream of such terror and agony that, for the moment, tom was stunned into inactivity. then, as he turned, he saw a great condor sweeping down out of the air, the wind fairly whistling through the big, outstretched wings.

"jove!" ejaculated tom. "can the bird be going to attack the woman?"

but this was not the object of the condor. it was aiming to strike, with its fierce talons, at a point some paces distant from where the woman stood, and in the intervals between her screams tom heard her cry, in her native tongue:

"my baby! my baby! the beast-bird will carry off my baby!"

then tom understood. the woman herb-gatherer had brought her infant with her on her quest, and had laid it down on a bed of soft grass while she worked. and it was this infant, wrapped as tom afterward saw in a piece of deer-skin, at which the condor was aiming.

"master shoot!" cried koku, pointing to the down-sweeping bird.

"you bet i'll shoot!" cried tom.

throwing his electric rifle to his shoulder, tom pressed the switch trigger. the unseen but powerful force shot straight at the condor.

the outstretched wings fell limp, the great body seemed to shrivel up, and, with a crash, the bird fell into the underbrush, breaking the twigs and branches with its weight. the electric rifle, a full account of which was given in the volume entitled "tom swift and his electric rifle," had done its work well.

with a scream, in which was mingled a cry of thanks, the woman threw herself on the sleeping child. the condor had fallen dead not three paces from it.

tom swift had shot just in time.