The Boy Aviators in Africa Part 13

Apparently some forgotten tribe had at some time or other been struck by the facial outline of the rocks and had cut into the flat surface, which was upturned to the sky, eyes and a mouth, the latter well provided with teeth, in each of which was drilled a tiny triangular hole.

While Frank was puzzling over the meaning of these apertures there came a repet.i.tion of the weird cry, but this time the lad was so startled that he almost lost his balance and fell backward.

The call seemed to proceed from his very feet. Then, all at once, he realized what it was.

The strange sounds proceeded from the mouth of the stone face.

Frank ran to the edge of the steep declivity that formed the nose.

"Say, Harry, and you too, Ben, examine the surface below there very carefully for any holes. They will probably be small ones and in a row."

"None this side," announced the searchers after a lengthy quest.

"Try the other," ordered Frank.

They did so and after a few minutes of careful scrutiny Harry shouted that they had found a row of small holes pierced in the rock just below where Frank stood.

"Then we have solved the mystery of the voice," exclaimed Frank.

"What do you mean?" demanded Harry.

"That it is nothing more or less than an arrangement of holes through which, when the wind blows in a stiff puff, air is forced with violence enough to cause the cry that disturbed us so much last night," was the reply.

This indeed was the solution, and had the boys known it there are many such rocks in Africa, carved out by some forgotten race, and the weird cries that the vent-holes give out in the wind doubtless acted as a powerful "fetish" to keep away troublesome enemies.

"No wonder the n.i.g.g.e.rs down below don't come near the Moon Mountains," said Harry, as they all buckled over the simple explanation of the phenomenon that had caused them so much alarm.

"I wouldn't care to, myself, unless I knew just what made that cry."

"It certainly was as depressing as anything I ever heard," said Frank, "and now having solved the great mystery--let's get back to work."

The three adventurers went at the job with a will. The line was about a hundred feet long and the method of procedure was this: Frank tested the straightness of the line, as accurately as possible with his eye, while Ben and Harry carried it stretched between them.

The end of each hundred feet was signalized by a stone, and Harry, who was at the end of the line, carried his end to this mark before they laid out a fresh hundred feet. In this way they must have measured off very nearly half-a-mile of the mountain-side when Frank gave a sudden sharp cry and pointed to a depression in the dark range immediately below them. As the others looked they echoed his cry and gave a dash forward.

Directly beneath them, about in the center of the little dip, was a cairn of rough stones perhaps four feet in height. In a few bounds they had reached the pile, which they knew meant the discovery of the ivory cache and the end of the most difficult part of their expedition. Little did they imagine the amazing things that were yet to happen to them and of which they were but on the threshold.

"Good Lord, look at that, boys!" exclaimed Frank, as they stood at the foot of the cairn.

There was a good reason for the boy's exclamation.

Distributed around the base of the pile were a dozen or, more human skulls.

"Are they those of white men?" asked Harry in an awed tone. Frank shook his head.

"No, they are those of negroes I believe," he replied after a careful examination, "and I imagine that Muley-Ha.s.san killed them after they erected the cache so that they would not be able to spread the knowledge of its whereabouts to any of the marauding tribes who might even brave the ghostly voice when such a great treasure of ivory tempted."

A shout from Ben, who had been walking round the pile examining it from every view-point interrupted them. They looked up and saw the old adventurer pointing to the mountain summit where it cut the sky.

Outlined against the deep azure was the object that had caused his exclamation. It was the figure of a man that had apparently been watching them intently.

But as they gazed the strange, crouched form suddenly vanished.

CHAPTER XI

THE AGE OF SIKASO

It was late afternoon of the day that Frank, Harry and Ben had left the River Camp. Lathrop, Billy, Barnes and old Sikaso had wandered into the jungle with their rifles, intent on bringing down some sort of game to replenish the camp larder. For hours they tramped about in the thick jungle and a fair measure of success had fallen to their rifles. Shortly before sundown the trio met in a glade not more than a mile from the camp and compared notes. To Billy's gun had fallen a plump young deer and Lathrop had brought down, not without a feeling of considerable pride, a species of wild hog which Sikaso proclaimed with a grunt was "heap good."

Flushed with triumph and carrying their own bag, the young hunters set out for the camp, arriving there at dusk. As has been told, it was not long after that that Frank's wireless from the Moon Mountains winged its way through the air and Lathrop was able to flash back in response an "all-well" message. The boys turned in early, Billy and Lathrop to their tent and old Sikaso to the rough shelter he had contrived for himself and which he declared was far more comfortable than any tent. Like a wild beast the savage old warrior disliked to have anything approaching a roof over him. It appeared to savor too much of a trap of some kind.

Billy might have been asleep five hours or so and it was approaching midnight when he heard a noise outside the tent door and a second later old Sikaso announced his presence by a whispered:

"Awake, Four-eyes, there is danger."

"What do you mean, Sikaso," demanded the half asleep reporter, "danger to our friends?"

"No; to us, and here and soon," was the disquieting response, "arouse your friend. We have no time to lose."

Billy was wide awake now and made a motion as if he would light the lantern.

Sikaso stopped him with a quick gesture.

"Do not light the lamp, my white brother," he whispered in the same tense tones, "to do so would be to reveal to those who are now approaching that we are awake and expect them. Rather let us pretend that we are unaware that they come and spring upon them like the leopard when she is least expected."

"Yes, but--" exclaimed Billy in a bewildered tone, "what do you mean, Sikaso, what enemies are coming? How do you know that they are approaching?"

"I have seen it in the smoke," was the somber reply; "the smoke never lies. After I lay down on my skins I could not sleep, I felt there was danger approaching us. From where I knew not. So I made the "fetish" fire. In it I saw a band of men coming toward us down the river and at the head of them was a dark man--a man you know well, my white brother with the four eyes."

"Diego!" exclaimed Billy divining the other's thought.

"Yes, Diego; cursed be the day that my war-axe did not cleave his ugly skull; but beside Diego there is another. Hearken to the words of Sikaso, the elephant in his rage is not more merciless, the serpent not more cunning, the crocodile not more savage in onslaught than this other. He is Muley-Ha.s.san, the Arab, and the deeds he has done, my brother, when recounted turn strong men's blood to water."

Small wonder that Billy, as he hastily roused Lathrop, felt a shudder run through him. He had heard enough from Frank of the ways of Muley-Ha.s.san to know that they could not well fall into the hands of a more pitiless foe and that now, with the Golden Eagle gone and the Boy Aviators already at the ivory cache, it was probable that the slave-dealer's rage would render him even more savage than was his wont.

In a few rapidly whispered words Billy apprised Lathrop of the situation. Like Billy, the other boy had no lack of pluck but his heart sank, as had his companion's, as he sensed the full meaning of Sikaso's warning.

"But perhaps the smoke was mistaken," he said eagerly, willing to grasp even at that straw of hope; but the old warrior's answer dashed his aspirations to the ground.

"The smoke is never mistaken," he said simply; but with such calm conviction that the boys, despite themselves, realized that the old Krooman had really the knowledge of grave peril approaching.

"Had we not better arm the other Kroomen?" asked Billy anxiously.

"It would be useless," was Sikaso's reply, "they are cowards. At the first sight of blood they would run to the forest like the sons of weaklings that they are."

"We must rouse Professor Wiseman at once," cried Billy.

"It is well," muttered Sikaso, "we shall need every man who can hold a rifle to-night but the professor is old, my brothers, and his heart is as a woman's."