A Little Philosophy.--A Cloud on the Horizon.--In the Midst of a Fog.--The Strange Balloon.--An Exact View of the Victoria.--The Palm-Trees.--Traces of a Caravan.--The Well in the Midst of the Desert.

On the morrow, there was the same purity of sky, the same stillness of the atmosphere. The balloon rose to an elevation of five hundred feet, but it had scarcely changed its position to the westward in any perceptible degree.

"We are right in the open desert," said the doctor. "Look at that vast reach of sand! What a strange spectacle! What a singular arrangement of nature! Why should there be, in one place, such extreme luxuriance of vegetation yonder, and here, this extreme aridity, and that in the same latitude, and under the same rays of the sun?"

"The why concerns me but little," answered Kennedy, "the reason interests me less than the fact. The thing is so; that's the important part of it!"

"Oh, it is well to philosophize a little, Dick; it does no harm."

"Let us philosophize, then, if you will; we have time enough before us; we are hardly moving; the wind is afraid to blow; it sleeps."

"That will not last forever," put in Joe; "I think I see some banks of clouds in the east."

"Joe's right!" said the doctor, after he had taken a look.

"Good!" said Kennedy; "now for our clouds, with a fine rain, and a fresh wind to dash it into our faces!"

"Well, we'll see, Dick, we'll see!"

"But this is Friday, master, and I'm afraid of Fridays!"

"Well, I hope that this very day you'll get over those notions."

"I hope so, master, too. Whew!" he added, mopping his face, "heat's a good thing, especially in winter, but in summer it don't do to take too much of it."

"Don't you fear the effect of the sun's heat on our balloon?" asked Kennedy, addressing the doctor.

"No! the gutta-percha coating resists much higher temperatures than even this. With my spiral I have subjected it inside to as much as one hundred and fifty-eight degrees sometimes, and the covering does not appear to have suffered."

"A cloud! a real cloud!" shouted Joe at this moment, for that piercing eyesight of his beat all the glasses.

And, in fact, a thick bank of vapor, now quite distinct, could be seen slowly emerging above the horizon. It appeared to be very deep, and, as it were, puffed out. It was, in reality, a conglomeration of smaller clouds. The latter invariably retained their original formation, and from this circumstance the doctor concluded that there was no current of air in their collected mass.

This compact body of vapor had appeared about eight o'clock in the morning, and, by eleven, it had already reached the height of the sun's disk. The latter then disappeared entirely behind the murky veil, and the lower belt of cloud, at the same moment, lifted above the line of the horizon, which was again disclosed in a full blaze of daylight.

"It's only an isolated cloud," remarked the doctor. "It won't do to count much upon that."

"Look, Dick, its shape is just the same as when we saw it this morning!"

"Then, doctor, there's to be neither rain nor wind, at least for us!"

"I fear so; the cloud keeps at a great height."

"Well, doctor, suppose we were to go in pursuit of this cloud, since it refuses to burst upon us?"

"I fancy that to do so wouldn't help us much; it would be a consumption of gas, and, consequently, of water, to little purpose; but, in our situation, we must not leave anything untried; therefore, let us ascend!"

And with this, the doctor put on a full head of flame from the cylinder, and the dilation of the hydrogen, occasioned by such sudden and intense heat, sent the balloon rapidly aloft.

About fifteen hundred feet from the ground, it encountered an opaque mass of cloud, and entered a dense fog, suspended at that elevation; but it did not meet with the least breath of wind. This fog seemed even destitute of humidity, and the articles brought in contact with it were scarcely dampened in the slightest degree. The balloon, completely enveloped in the vapor, gained a little increase of speed, perhaps, and that was all.

The doctor gloomily recognized what trifling success he had obtained from his manoeuvre, and was relapsing into deep meditation, when he heard Joe exclaim, in tones of most intense astonishment:

"Ah! by all that's beautiful!"

"What's the matter, Joe?"

"Doctor! Mr. Kennedy! Here's something curious!"

"What is it, then?"

"We are not alone, up here! There are rogues about! They've stolen our invention!"

"Has he gone crazy?" asked Kennedy.

Joe stood there, perfectly motionless, the very picture of amazement.

"Can the hot sun have really affected the poor fellow's brain?" said the doctor, turning toward him.

"Will you tell me?--"

"Look!" said Joe, pointing to a certain quarter of the sky.

"By St. James!" exclaimed Kennedy, in turn, "why, who would have believed it? Look, look! doctor!"

"I see it!" said the doctor, very quietly.

"Another balloon! and other passengers, like ourselves!"

And, sure enough, there was another balloon about two hundred paces from them, floating in the air with its car and its aeronauts. It was following exactly the same route as the Victoria.

"Well," said the doctor, "nothing remains for us but to make signals; take the flag, Kennedy, and show them our colors."

It seemed that the travellers by the other balloon had just the same idea, at the same momen............