It was the voice of the mountain once more.
With yells of dismay and terror the remainder of the gorilla band instantly dashed up the rocky mountain-side dragging with them, in grotesquely human fashion some of their wounded. Several of these, however, still lay on the ground and the boys put them out of their misery with a few well-directed shots. A pathetically human look lingered in the eyes of some of the injured gorillas and Harry burst out with:
"This is awful work. I"d rather fight a dozen bands of cannibals than have to do this."
"And yet," replied Frank, "if we hadn"t killed them they"d have killed us."
At last the unpleasant work was over and the ivory was rapidly loaded into the aeroplane. But here an unantic.i.p.ated difficulty manifested itself. Obviously the aeroplane would be too heavily laden if she attempted to carry all or even a good part of the ivory.
"Now we are stuck," cried Harry.
"Hold on," exclaimed Frank with a smile, "I antic.i.p.ated this. We are going to turn the Golden Eagle into a tow-boat."
"A tow-boat?"
"That"s what I said."
"What do you mean?"
Frank, in reply, bent over the stem-locker of the aeroplane and drew out what Harry instantly recognized as the silk envelope of an experimental dirigible they had built the year before.
"Now then," said Frank, "give a hand here."
They all three pulled and hauled till the envelope was spread level on the ground, all folds and creases having been carefully shaken out.
"Well," said Harry, "this would carry an awful weight of ivory, but how are you going to inflate it?"
"With these cylinders," was the answer as Frank opened the store-room below the floor of the Golden Eagle and pointed to a dozen cylindrical steel receptacles. "They contain more than enough pure hydrogen gas at a high pressure," he explained, "to inflate the bag."
In his enthusiasm Harry waved his helmet and Ben did the same.
"An aerial express, hurray!"
The inflation hose was soon connected to the first of the cylinders and with a hiss the gas rushed into the bag when a turn of the wrench set free the precious stuff. Slowly the big yellow envelope swelled and a.s.sumed shape until by the time the last cylinder was empty it was tugging and straining to rise. But the boys had weighted it down with rocks and pegged its net ropes to the ground.
The ivory was loaded into a sort of rope basket, like those used to hoist cargo aboard a ship, and in a short time, so quickly did they work, they were ready for the air, so far as what Harry called "the airbarge" was concerned.
"We shall have to strip the Eagle," decided Frank, when the inflation job was finished.
"Of everything that we can spare," added Harry, setting to work at once to rip the transoms and detach the bolts that held the heavy wireless apparatus in place. As he did so, Frank was moved by a sudden thought.
"Hold on a second, Harry," he shouted, "I"ll call up the river camp before we cut off all communication."
Rapidly he sent out the call. Again and again his nervous finger agitated the key--but there was no response.
"They--they don"t answer," gasped Frank at last--heavy anxiety in his tones.
"Oh, Frank, do you think anything serious is the matter?" cried Harry.
"It may only be that the apparatus is out of order," replied the elder brother seriously; "but it looks bad. That field wireless was in prime condition and it would be next to impossible for them to fail to receive our call."
"Well, there is only one thing to be done," remarked the practical Ben Stubbs.
"And that is--?" queried Harry.
"To get back there as soon as possible, for if they need us they need us dern bad," was the energetic reply.
Half an hour later the Golden Eagle, stripped of all her heavy gear and only carrying just enough gasoline to get her to the river camp, where the adventurers expected to find a reserve supply, rose slowly into the air with her queer tow tugging behind on the wireless ground rope. The boys had cached the wireless apparatus and the other gear, to be called for at some more opportune time. To their great regret, also, they had had to leave some of the ivory behind them. But the majority of what they did not dare trust to the gas-bag they carried in the cha.s.sis. Luckily for them there was hardly a breath of wind and the novel carrier towed well.
As the occupants of the great aeroplane gazed back at the sinister Moon Mountains as they fast faded out--they saw silhouetted against the evening sky a dark figure.
It was recognized at once as one of the beaten gorillas scouting to see if the terrible white men had really gone.
"There"s the man we saw this afternoon," laughed, Frank, as with rapidly beating propellers the Golden Eagle II winged her way with the convoy toward the River Camp.
CHAPTER XIV
AN ESCAPE--AND WHAT CAME OF IT
From the pace at which Muley-Ha.s.san"s band traversed the jungle paths it was evident to the two young captives that there was imperative need in Muley-Ha.s.san"s mind of arriving somewhere at a set time. The usual noonday rest, which even the avaricious slave-trader was in the habit of taking, was not observed and the travelers pressed straight on. Lathrop and Billy were almost ready to drop with fatigue when that evening, just at dusk, they arrived at the bank of a muddy river which Muley-Ha.s.san, impatient as he was to proceed, decided it would be unwise to ford till daylight--when they could look for a good crossing place. At the spot which they had halted, the stream--swollen apparently by rains in the mountains--roared between its banks, in a dark chocolate-colored flood.
Muley-Ha.s.san himself was the only one of his band provided with a tent, or anything resembling one, and the boys shared the common bed of the rest of the party--which was the ground. A more unwholesome resting-place in Africa, particularly on the steamy, swampy banks of a river, could hardly be imagined. So indeed Muley-Ha.s.san seemed to think, for after a short time, during which the boys vainly tried to secure some sleep, he ordered Diego to provide them with blankets to place between themselves and the bare earth.
"I expect to get a good price for them eventually," he said, "and I don"t want to lose them unless I have to."
As the boys" wrists and ankles were bound with tough gra.s.s while there was no particular attempt made to watch them, and soon the snores of the camp bespoke that it was at rest. Then it was that Billy whispered to Lathrop.
"Now"s our time to try for it!"
"Try for what?" whispered back Lathrop in an inert tone.
"To get away."
"What!"
"I mean it. I found a sharp stone imbedded in the ground near to me and I have nearly sawed through my wrist-bands."
After a few seconds" more vigorous sc.r.a.ping against the stone, Billy whispered:
"My hands are free. Wait till I wiggle my fingers and get up some circulation and then we"ll make our attempt--"
When he had once more got full control of his cramped fingers Billy stooped cautiously over and loosened the thongs about his ankles.
So tightly had they been drawn, though, that it took some little time to get the cramps out of them. At last, however, the boy succeeded in restoring the circulation and then he was ready for the most daring step of his attempt. Cautiously he fell on his hands and knees and began to crawl toward the nearest of the sleeping slave-traders.