"What does that mean?" asked Mr. Durban, who did not know much about machinery.
"It means that I've got to put a new cylinder in," went on Tom.
"It's quite a job, too, but we can't make gas without it!"
"Well, can't you do it just as well up in the air as down here?"
asked Mr. Durban. "Make an ascension, Tom, and do the repairs up above, where we've got good air, and where--"
He paused suddenly, and seemed to be listening.
"What is it?" asked the young inventor quickly. There was no need to answer, for, from the jungle without, came the dull booming of the war drums of some natives.
"That's what I was afraid of!" cried the old elephant hunter, catching up his gun. "Some black scout has seen us and is summoning his tribesmen. Hurry, Tom, send up the ship, and we'll take care of the savages."
"But I CAN'T send her up!" cried Tom.
"You can't? Why not?"
"Because the gas machine won't work until I put in a new cylinder, and that will take at least a half a day."
"Go up as an aeroplane then!" cried Mr. Damon. "Bless my monkey wrench, Tom, you've often done it before."
For answer Tom waved his hand toward the thick jungle all about them.
"We haven't room to get a running start of ten feet." he said, "and without a start the airship can never rise as a mere aeroplane. The only way we can get up from the jungle is like a balloon, and without the gas--"
He paused significantly. The sound of the war drums became louder, and to it was added a weird singing chant.
"The natives!" cried Mr. Anderson. "They're coming right this way!
We must fight them off if they attack us!"
"Where's the electric rifle?" asked Ned. "Get that out, Tom!"
"Wait!" suggested Mr. Durban. "This is serious! It looks as if they were going to attack us, and they have us at a disadvantage. Our only safety is in flight, but as Tom says we can't go up until the gas machine is fixed, he will have to attend to that part of it while we keep off the black men. Tom, we can't spare you to fight this time! You repair the ship as soon as you can, and we'll guard her from the natives. And you've got to work lively!"
"I will!" cried the young inventor. "It's luck we have a spare cylinder!"
Suddenly there was a louder shout in the jungle and it was followed by a riot of sound. War drums were beaten, tom-toms clashed and the natives howled.
"Here they are!" cried Mr. Anderson.
"Bless my suspenders!" shouted Mr. Damon. "Where is my gun?"
"Here, you take mine, and I'll use the electric rifle," answered the elephant hunter. As he spoke there was a hissing sound in the air and a flight of spears passed over the airship.
The defenders slipped outside, while Tom, with Ned to help him, worked feverishly to repair the break. They were in a serious strait, for with the airship practically helpless they were at the mercy of the natives. And as Tom glanced momentarily from the window, he saw scores of black, half-naked forms slipping in and out among the trees and trailing vines.
Soon the rifles of his friends began to crack, and the yells of the natives were changed to howls of anguish. The electric weapon, though it made no noise, did great execution.
"I only hope they don't puncture the gas bag," murmured Tom, as he began taking the generating machine apart so as to get out the cracked cylinder.
"If they do, it's all up with us," murmured Ned.
After their first rush, finding that the white men were on the alert, the blacks withdrew some distance, where their spears and arrows were not so effective. Our friends, including Andy Foger, and the German, kept up a hot fire whenever a skulking black form could be seen.
But, though the danger from the spears and arrows was less, a new peril presented itself. This was from the blow guns. The curious weapons shot small arrows, tipped with tufts of a cottony substance in place of feathers, and could be sent for a long distance. The barbs were not strong enough to pierce the tough fabric of the gas bag, as a spear or arrow would have done, but there was more danger from them to our friends who were on deck.
"Those barbs may be poisoned," said Mr. Durban, "and in case any one is wounded, the wound, though it be but a scratch, must be treated with antiseptics. I have some."
This course was followed, the elephant hunter being wounded twice, and Andy Foger and Mr. Damon once each. There was not a native to be seen now, for they were hiding behind the trees of the jungle, but every now and then a blowgun barb would whizz out of the forest.
Finally Mr. Durban suggested that they erect improvised shelters, behind which they could stand with their rifle, and breastworks were made out of packing boxes. Then our friends were comparatively safe.
But they had to be on the alert, and it was nervous work, for they could not tell what minute the blacks would rush from the jungle, and, in spite of the fire from the electric rifle and other guns, overwhelm the ship.
It was very trying to Tom and Ned, for they had to work hard and rapidly in the close engine room. The sweat dripped down off them, but they kept at it. It was three hours before the broken cylinder was removed, and it was no light task to put in the other, for the valves had to be made very tight to prevent leakage.
The two lads stopped to get something to eat, while the guards kept sharp watch against a surprise. At intervals came a flight of barbs, and occasionally a black form could be seen, when it was instantly fired at. Several times the barbaric noise of the tom-toms and war drums, with which the shouts of the natives mingled, broke out deafeningly.
"Think you can repair it by night?" asked Mr. Durban anxiously of Tom.
"I hope so," was the response.
"Because if we have to stay here after dark--well, I don't want to do it if I can help it," finished the hunter.
Neither did the young inventor, and he redoubled his efforts to make the repairs. It was getting dark when the last belt was in place, and it was high time, too, for the natives were getting bolder, creeping up through the forest to within shooting distance with their arrows and spears.
"There!" cried Tom at length. "Now we'll see if she works!" Once more he pulled the starting lever, and this time there was the welcome hiss of the gas.
"Hurrah!" cried Ned.
The young inventor turned the machine on at full power. In a few minutes the Black Hawk trembled through her length.
"She's going up! Bless my balloon basket! She's going up!" cried Mr.
Damon.
The natives must have suspected that something unusual was going on, for they made a sudden rush, yelling and beating their drums. Mr.
Durban and the others hurried out on deck and fired at them, but there was little more need. With a bound the airship left the earth, being rapidly carried up by the gas. The blacks sent a final shower of spears after her, but only one was effective, slightly wounding the German. Then Tom started the motor, the propellers whizzed, and the Black Hawk was once more under way, just as night settled over the jungle, and upon the horde of black and howling savages that rushed around, maddened over the escape of their intended victims.
No further accidents marred the trip to the coast, which was reached in due time, and very glad our friends were to be away from the jungle and the land of the red pygmies.
A division was made of the ivory, and Tom's share was large enough to provide him with a substantial amount. Ned and Mr. Damon were also given a goodly sum from the sale of the tusks. The big ones, from the "rogue," were shipped to the man who had commissioned Mr.
Durban to secure them for him.
"Well, now for home," said Tom, when the airship had been taken apart for shipment. "I guess you'll be glad to get back to the United States, won't you, friends?"
"That's what," agreed Andy Foger. "I think I'm done with airships.
Ugh! When I think of those red dwarfs I can't sleep nights!"
"Yah, dot iss so!" agreed the German.