Part 11 (2/2)

”Well, thank goodness, we've got something green and pleasant to look at,” remarked Ben, as they set about transforming the cha.s.sis of the Golden Eagle into a comfortable tent by means of running up the canvas curtains on the aluminum frames provided for that purpose. Thus equipped, the cha.s.sis served the uses of an improved tent, as the floor was well above the ground and out of all danger of the unwholesome, vapors rising from the ground and also the scorpions and other reptiles.

But if the oasis itself was a pretty spot, it was made doubly so by the contrast it afforded to the scenery surrounding it. On all sides shot up frowning walls of rugged black rock which seemed to have been torn and ripped in some remote period by a terrific convulsion of nature. In places, too, the rock ma.s.ses seemed to have been seared by subterranean fires. Frank gazed upward at the terrific character of the scenery about them.

”We shall need the rope-ladder,” he announced suddenly after a long silence.

”The rope-ladder?” inquired Harry, ”what for?”

Frank laughed.

”I mean the rope-ladder we use in the Golden Eagle. As you know, the only way to locate the cache is to strike a direct line down from the nose of the upturned face. That will bring us to the small cairn or pile of rocks that marks the Arab's hiding-place.”

”He could hardly have chosen a better,” remarked Harry. ”Who would ever guess, unless they had the key to the mystery, that these mountains held such a fortune in tusks.”

The rest of that day was spent in overhauling the outfit which they would need to use on their expedition of the morrow. Luckily the boots they wore had been fitted with ”hob-nails” so that they were ideal for the tough climb that they had ahead of them. Each member of the three was to carry a pick and of course they all were to be armed, carrying several rounds of ammunition each in their cartridge-belts.

That night after a supper of fried ham, canned corn and pancakes--all cooked by the skilful Ben over a fire of wood collected from the little grove--Frank sent out a wireless to the members of the camp on the river bank and felt much rea.s.sured when Lathrop's ”All well--good luck,” came back through the air. It was delightfully cool on the mountain-side after the oppressive fetid air of the river and its neighborhood, and as Ben had remarked before they turned in:

”Fine weather for sleeping.”

But sleep would not come to Frank. He tossed and turned on his transom bed and several times gazed out into the night through the canvas curtains. An unaccountable feeling of unrest possessed him.

Could they get the ivory out of the cache before Muley-Ha.s.san and his band arrived by land?

Fast as they had traveled through the air Frank realized that the Arab, who doubtless by this time had been informed by the treacherous Diego of the boys' bold dash, would push on at furious speed in order to head them off. That he would come accompanied by a well-armed band Frank could not doubt. He and Harry and Ben could only put up a feeble resistance against such an attack. There was only one chance to secure the ivory and that was to get at it before the Arab arrived. It all depended then on how quickly they could find the cache. Frank lit the lantern and s.h.i.+elding it so that it would not strike in the eyes of his sleeping brother, drew out the map and scanned it attentively.

Yes, here were the directions written in the queer hand of Muley-Ha.s.san's follower.

”A line from the nose straight down to the cairn of stones.”

It seemed simple enough and certainly the nose of the Upturned Face was as clearly to be made out as a s.h.i.+p at sea. But Frank had been too long trained in the hard school of adventure to underestimate the difficulties of any piece of work. They faced a hard job and none realized the fact better than the young leader.

At last he blew the lantern out and once more composed himself to sleep. He was just dozing off when a sufficiently startling interruption occurred. One which drove all further thoughts of rest from his head.

It was an extraordinary sound that brought the boy out of his bed with a bound and caused him to clutch his revolver with a heart that beat loud and thick in spite of himself.

Clutching his weapon the boy rushed to the door of the cha.s.sis tent and gazed out.

There was a bright moon which threw into inky blackness the depressions of the rugged mountains and threw up their projections into a blue glare. It was almost as light as day under that wonderful African moon. Had there been any one near the boy must have been able to see them.

But look as he would there was not a soul in sight. All about him stretched the barren frowning mountains sleeping under the moon.

But the sound that he had heard?

There was no mistaking it. It had been too like the low humming of a human voice for him to have been misled. Perhaps he had been dreaming?

But as if to give the lie to any such supposition the strange sound that had so alarmed him at that moment made itself manifest once more:

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