His companions, understanding him, at last came to his assistance, and soon took their places in the car.
"Now, Joe," said the doctor, "throw over about fifty pounds of your mineral treasures."
Joe did not hesitate, though a pang of regret shot through him. The balloon began to rise.
"Just in time," said the doctor.
In fact the simoon came upon them like a thunderbolt. A little later and the "Victoria" would have been smashed, torn to pieces, annihilated.
The terrible whirlwind struck them and the balloon was covered with a shower of sand.
"More of that ballast, Joe," cried the doctor.
"There it goes," said Joe, throwing over an immense piece of quartz.
The "Victoria" mounted rapidly above the whirlwind, but surrounded by an immense vacuum of air, it was hurried along by the current at a frightful pace above the foaming sea of sand.
Neither Samuel, Dick, nor Joe spoke a word. They looked on in hope, and were, moreover, refreshed by the wind of this tempest.
At three o'clock the storm abated; the sand in falling formed a quantity of little heaps, the sky reappeared in all its former tranquillity. The "Victoria," now motionless, was in full view of an oasis, a little isle covered with green trees and rising from the surface of this ocean.
"Water! water!" exclaimed the doctor, and immediately opening the valve he permitted the escape of the hydrogen and descended gently at about 200 paces from the oasis. During a period of four hours they had traveled 240 miles.
The car was duly balanced, and Kennedy, followed by Joe, got down on the ground.
"Take your rifles," said the doctor, "and be cautious."
Dick caught up his carbine, Joe took one of the rifles. They advanced quickly up to the trees and penetrated amid the fresh verdure which announced the abundance of water. They took no notice of some large footprints and of the fresh trail which was indicated upon the damp ground.
Suddenly a roar resounded within twenty paces.
"'Tis the roar of a lion!" cried Joe.
