"Well," said the doctor, "it only remains for us to make them a signal. Take the flag, Kennedy, and show them our colors."
It seemed that the travelers in the other balloon had conceived the same idea at the same time, for a similar flag repeated the identical signal in a hand which held it in the same position.
"What is the meaning of that?" asked the Scot.
"They are monkeys," said Joe, "and they are imiating us."
"It means," replied Ferguson, laughing, "that it is yourself who is making the signal to you, my dear Dick; that is to say, that we ourselves are in the other car, and that that balloon is really our own 'Victoria.'"
"Well, sir, with all due respect to you," said Joe, "you will never make me believe that."
"Get up on the edge of the car, Joe, and wave your arms; then then you will see if I am right."
Joe obeyed, and his gestures were exactly and instantaneously repeated.
"It is only the effect of mirage," said the doctor, "nothing more a simple optical delusion—and is due to the unequal rarefaction of the air-strata—that's all."
"It is most extraordinary," said Joe, who could not take it all in, and kept waving his arms about to convince himself on the subject.
"A curious sight, indeed!" said Kennedy. "It is pleasant too to see our brave 'Victoria.' Do you know she has quite a grand appearance, and floats in a right royal manner."
"You have explained this appearance very well in your own way," said Joe, "but it is a singular effect all the same."
But the "double" of the "Victoria" gradually disappeared, the clouds ascended to a great height above the balloon, which did not attempt to follow them, and in about an hour they disappeared.
The wind, even hitherto scarcely perceptible, appeared to drop altogether. The doctor, in despair, descended towards the ground.
The travelers, who had been aroused from their preoccupation by the appearance of the mirage, again yielded
