The moonlight revealed glimpses of one district half in ruins; and some pinnacles of mosques and minarets shot up here and there, glistening in the silvery rays. The doctor took a stellar observation, and discovered that he was in the latitude of Aghades.

This city, once the seat of an immense trade, was already falling into ruin when Dr. Barth visited it.

The Victoria, not being seen in the obscurity of night, descended about two miles above Aghades, in a field of millet. The night was calm, and began to break into dawn about three o'clock A.M.; while a light wind coaxed the balloon westward, and even a little toward the south.

Dr. Ferguson hastened to avail himself of such good fortune, and rapidly ascending resumed his aerial journey amid a long wake of golden morning sunshine.

CHAPTER THIRTY-EIGHTH.

A Rapid Passage.--Prudent Resolves.--Caravans in Sight.--Incessant Rains.-- Goa.--The Niger.--Golberry, Geoffroy, and Gray.--Mungo Park.--Laing.-- Rene Caillie.--Clapperton.--John and Richard Lander.

The 17th of May passed tranquilly, without any remarkable incident; the desert gained upon them once more; a moderate wind bore the Victoria toward the southwest, and she never swerved to the right or to the left, but her shadow traced a perfectly straight line on the sand.

Before starting, the doctor had prudently renewed his stock of water, having feared that he should not be able to touch ground in these regions, infested as they are by the Aouelim-Minian Touaregs. The plateau, at an elevation of eighteen hundred feet above the level of the sea, sloped down toward the south. Our travellers, having crossed the Aghades route at Murzouk--a route often pressed by the feet of camels--arrived that evening, in the sixteenth degree of north latitude, and four degrees fifty-five minutes east longitude, after having passed over one hundred and eighty miles of a long and monotonous day's journey.

During the day Joe dressed the last pieces of game, which had been only hastily prepared, and he served up for supper a mess of snipe, that were greatly relished. The wind continuing good, the doctor resolved to keep on during the night, the moon, still nearly at the full, illumining it with her radiance. The Victoria ascended to a height of five hundred feet, and, during her nocturnal trip of about sixty miles, the gentle slumbers of an infant would not have been disturbed by her motion.

On Sunday morning, the direction of the wind again changed, and it bore to the northwestward. A few crows were seen sweeping through the air, and, off on the horizon, a flock of vultures which, fortunately, however, kept at a distance.

The sight of these birds led Joe to compliment his master on the idea of having two balloons.

"Where would we be," said he, "with only one balloon? The second balloon is like the life-boat to a ship; in case of wreck we could always take to it and escape."

"You are right, friend Joe," said the doctor, "only that my life-boat gives me some uneasiness. It is not so good as the main craft."

"What do you mean by that, doctor?" asked Kennedy.

"I mean to say that the new Victoria is not so good as the old one. Whether it be that the stuff it is made of is too much worn, or that the heat of the spiral has melted the gutta-percha, I can observe a certain loss of gas. It don't amount to much thus far, but still it is noticeable. We have a tendency to sink, and, in order to keep our elevation, I am compelled to give greater dilation to the hydrogen."

"The deuce!" exclaimed Kennedy with concern; "I see no remedy for that."

"There is none, Dick, and that is why we must hasten our progress, and even avoid night halts."

"Are we still far from the coast?" asked Joe.

"Which coast, my boy? How are we to know whither chance will carry us? All that I can say is, that Timbuctoo is still about four hundred miles to the westward.

"And how long will it take us to get there?"

"Should the wind not carry us too far out of the way, I hope to reach that city by Tuesday evening."

"Then," remarked Joe, pointing to a long file of animals and men winding across the open desert, "we shall arrive there sooner than that caravan."

Ferguson and Kennedy leaned over and saw an immense cavalcade.