THE ARAB'S CACHE
The mysterious cries were not repeated that night although the boys
laid awake till daylight listening for any repetition. No theory
they could advance, although these ranged all the way from cannibals
and gorillas to ghosts, had any effect on the solution of the
mystery. They finally agreed to trust to solving it in some chance
way, and like sensible boys did not continue to worry themselves
over the unsolvable.
Frank's first action was to send out a wireless to the river camp
and to his great relief he found that events there were still
proceeding with the same regularity as before. Nothing had occurred
to mar the even life of the young adventurers left behind. This was
the tenor of the message, but there was something about it that
worried Frank. Lathrop, he knew, was an expert wireless operator,
but the sending that he performed that morning was so jerky and
irregular that the rankest amateur might have done better.
"What is the matter?" asked Frank sharply after the sending had
become even more unskilled and shaky.
There was no answer; which caused Frank a vague feeling of
apprehension. He speedily drove this impression from his mind,
however, with:
"Pshaw! the sleepless night I passed has made me nervous."
After breakfast there was so much to be done that there was no more
time to waste on gloomy forebodings and the boys started, as soon as
the camp had been put in order, on their expedition up the
mountain-side to the Upturned Face--which was to be the starting
point for the uncovering of the secret ivory hoard.
The climb was quite as stiff as Frank had anticipated and, laden as
they were with the rope-ladder and the other equipment, it was
rendered even tougher. All three carried water-canteens covered
with wet felt, containing half-a-gallon each. Frank had insisted on
this as it was doubtful if they could find water at the summit of
the mountain.
As the sun rose higher in the sky and beat down on the bare rock
ridges over which the adventurers were making their way, it became
as uncomfortable as any expedition on which the boys had ever beer
engaged.
"Talk about New Mexico or Death Valley," exclaimed Harry, "I feel
like a piece of butter rolled up in a paper and I've melted."
"I feel like a Welsh rarebit myself," laughed Frank, "how about you,
Ben?"
"I feel like a pot of boiling tar with a fire lighted under me,"
growled the veteran angrily; "consarn these rocks, I'd give a whole
lot for a bit of that shade we left behind us."
Despite the discomfort and the heat, however, they struggled on up
the mountain-side, frequently using the rope-ladder to get over
rough places, and at about noon they stood beneath the steep rock
cliff that formed the nose of the upturned face.
It was easy enough then to reach a spot below the tip and Frank,
with a long cord he had brought for the purpose, laid out a straight
line from the point down the southern slope of the mountain-side.
While they were busy about this they were startled by a repetition
of the same strange cry, half-warning, half-savage, that they had
been so alarmed by the night before.
"A-ho-o-o-o-AH-H-O-O-O-a-h-o-o-hoo-o-o-o-o!"
"Great Scott," yelled Harry, "what on earth do you think of that?"
Frank--considerably startled himself--had, however, made a
determined effort to ascertain the source of the sound as it rose
and fell in its strange cadence.
"I've got it!" he shouted; now with a cry of triumph.
"Got what?" cried Harry, as if he feared his brother had suddenly
become infected with some strange complaint--"rabies or the pip?"
"The noise--I mean I know where it comes from," cried the excited
boy.
"Where?" chorused Ben and Harry.
"From somewhere about the Upturned Face," cried Frank triumphantly,
"Hark!"
The strange wailing cry rang out once more. They all listened
intently.
Sure enough it seemed to proceed from the sinister countenance
carved in the living rock above them.
"Well, here's where we end this mystery for all time," shouted
Frank, drawing his revolver, "who is game to follow me?"
Of course Harry and Ben rushed to his side, and while the echo of
the mysterious cry was still sobbing and sighing among the crags
they dashed back up the mountain-side utterly oblivious now to the
heat or anything but their determination to discover who or what had
uttered the extraordinary cry. The side of the nose--or the nostril
so to speak--was formed of a wall of rock fully twelve feet in
height.
"You fellows give me a boost up there and I'll travel right along
the face till I find out where the racket comes from."
On Ben's strong shoulders Frank was soon hoisted up to a height
where he could lay hold of a projecting bit of rock and shin himself
up on to the top of the nose.
"Look out he doesn't think you are a fly and try to brush you off,"
laughed Harry from below.
"No danger of that," shouted back Frank, "unless I lit on him in the
Golden Eagle."
The surface of the face was as remarkable as its profile.
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 repetition 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 niggers 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-Hassan 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.