the next day, the 15th of june, about five o'clock in the morning, phil evans left his cabin. perhaps he would today have a chance of speaking to robur? desirous of knowing why he had not appeared the day before, evans addressed himself to the mate, tom turner.

tom turner was an englishman of about forty-five, broad in the shoulders and short in the legs, a man of iron, with one of those enormous characteristic heads that hogarth rejoiced in.

"shall we see mr. robur to-day?" asked phil evans.

"i don't know," said turner.

"i need not ask if he has gone out."

"perhaps he has."

"and when will he come back?"

"when he has finished his cruise."

and tom went into his cabin.

with this reply they had to be contented. matters did not look promising, particularly as on reference to the compass it appeared that the "albatross" was still steering southwest.

great was the contrast between the barren tract of the bad lands passed over during the night and the landscape then unrolling beneath them.

the aeronef was now more than six hundred miles from omaha, and over a country which phil evans could not recognize because he had never been there before. a few forts to keep the indians in order crowned the bluffs with their geometric lines, formed oftener of palisades than walls. there were few villages, and few inhabitants, the country differing widely from the auriferous lands of colorado many leagues to the south.

in the distance a long line of mountain crests, in great confusion as yet, began to appear. they were the rocky mountains.

for the first time that morning uncle prudent and phil evans were sensible of a certain lowness of temperature which was not due to a change in the weather, for the sun shone in superb splendor.

"it is because of the "albatross" being higher in the air," said phil evans.

in fact the barometer outside the central deck-house had fallen 540 millimeters, thus indicating an elevation of about 10,000 feet above the sea. the aeronef was at this altitude owing to the elevation of the ground. an hour before she had been at a height of 13,000 feet, and behind her were mountains covered with perpetual snow.

there was nothing uncle prudent and his companion could remember which would lead them to discover where they were. during the night the "albatross" had made several stretches north and south at tremendous speed, and that was what had put them out of their reckoning.

after talking over several hypotheses more or less plausible they came to the conclusion that this country encircled with mountains must be the district declared by an act of congress in march, 1872, to be the national park of the united states. a strange region it was. it well merited the name of a park—a park with mountains for hills, with lakes for ponds, with rivers for streamlets, and with geysers of marvelous power instead of fountains.

in a few minutes the "albatross" glided across the yellowstone river, leaving mount stevenson on the right, and coasting the large lake which bears the name of the stream. great was the variety on the banks of this basin, ribbed as they were with obsidian and tiny crystals, reflecting the sunlight on their myriad facets. wonderful was the arrangement of the islands on its surface; magnificent were the blue reflections of the gigantic mirror. and around the lake, one of the highest in the globe, were multitudes of pelicans, swans, gulls and geese, bernicles and divers. in places the steep banks were clothed with green trees, pines and larches, and at the foot of the escarpments there shot upwards innumerable white fumaroles, the vapor escaping from the soil as from an enormous reservoir in which the water is kept in permanent ebullition by subterranean fire.

the cook might have seized the opportunity of securing an ample supply of trout, the only fish the yellowstone lake contains in myriads. but the "albatross" kept on at such a height that there was no chance of indulging in a catch which assuredly would have been miraculous.

in three quarters of an hour the lake was overpassed, and a little farther on the last was seen of the geyser region, which rivals the finest in iceland. leaning over the rail, uncle prudent and phil evans watched the liquid columns which leaped up as though to furnish the aeronef with a new element. there were the fan, with the jets shot forth in rays, the fortress, which seemed to be defended by waterspouts, the faithful friend, with her plume crowned with the rainbows, the giant, spurting forth a vertical torrent twenty feet round and more than two hundred feet high.

robur must evidently have been familiar with this incomparable spectacle, unique in the world, for he did not appear on deck. was it, then, for the sole pleasure of his guests that he had brought the aeronef above the national domain? if so, he came not to receive their thanks. he did not even trouble himself during the daring passage of the rocky mountains, which the "albatross" approached at about seven o'clock.

by increasing the speed of her wings, as a bird rising in its flight, the "albatross" would clear the highest ridges of the chain, and sink again over oregon or utah, but the maneuver was unnecessary. the passes allowed the barrier to be crossed without ascending for the higher ridges. there are many of these canyons, or steep valleys, more or less narrow, through which they could glide, such as bridger gap, through which runs the pacific railway into the mormon territory, and others to the north and south of it.

it was through one of these that the "albatross" headed, after slackening speed so as not to dash against the walls of the canyon. the steersman, with a sureness of hand rendered more effective by the sensitiveness of the rudder, maneuvered his craft as if she were a crack racer in a royal victoria match. it was really extraordinary. in spite of all the jealousy of the two enemies of "lighter than air," they could not help being surprised at the perfection of this engine of aerial locomotion.

in less than two hours and a half they were through the rockies, and the "albatross" resumed her former speed of sixty-two miles an hour. she was steering southwest so as to cut across utah diagonally as she neared the ground. she had even dropped several hundred yards when the sound of a whistle attracted the attention of uncle prudent and phil evans. it was a train on the pacific railway on the road to salt lake city.

and then, in obedience to an order secretly given, the "albatross" dropped still lower so as to chase the train, which was going at full speed. she was immediately sighted. a few heads showed themselves at the doors of the cars. then numerous passengers crowded the gangways. some did not hesitate to climb on the roof to get a better view of the flying machine. cheers came floating up through the air; but no robur appeared in answer to them.

the "albatross" continued her descent, slowing her suspensory screws and moderating her speed so as not to leave the train behind. she flew about it like an enormous beetle or a gigantic bird of prey. she headed off, to the right and left, and swept on in front, and hung behind, and proudly displayed her flag with the golden sun, to which the conductor of the train replied by waving the stars and stripes.

in vain the prisoners, in their desire to take advantage of the opportunity, endeavored to make themselves known to those below. in vain the president of the weldon institute roared forth at the top of his voice, "i am uncle prudent of philadelphia!" and the secretary followed suit with, "i am phil evans, his colleague!" their shouts were lost in the thousand cheers with which the passengers greeted the aeronef.

three or four of the crew of the "albatross" had appeared on the deck, and one of them, like sailors when passing a ship less speedy than their own, held out a rope, an ironical way of offering to tow them.

and then the "albatross" resumed her original speed, and in half an hour the express was out of sight. about one o'clock there appeared a vast disk, which reflected the solar rays as if it were an immense mirror.

"that ought to be the mormon capital, salt lake city," said uncle prudent. and so it was, and the disk was the roof of the tabernacle, where ten thousand saints can worship at their ease. this vast dome, like a convex mirror, threw off the rays of the sun in all directions.

it vanished like a shadow, and the "albatross" sped on her way to the southwest with a speed that was not felt, because it surpassed that of the chasing wind. soon she was in nevada over the silver regions, which the sierra separates from the golden lands of california.

"we shall certainly reach san francisco before night," said phil evans.

"and then?" asked uncle prudent.

it was six o'clock precisely when the sierra nevada was crossed by the same pass as that taken by the railway. only a hundred and eighty miles then separated them from san francisco, the californian capital.

at the speed the "albatross" was going she would be over the dome by eight o'clock.

at this moment robur appeared on deck. the colleagues walked up to him.

"engineer robur," said uncle prudent, "we are now on the very confines of america! we think the time has come for this joke to end."

"i never joke," said robur.

he raised his hand. the "albatross" swiftly dropped towards the ground, and at the same time such speed was given her as to drive the prisoners into their cabin. as soon as the door was shut, uncle prudent exclaimed,

"i could strangle him!"

"we must try to escape." said phil evans.

"yes; cost what it may!"

a long murmur greeted their ears. it was the beating of the surf on the seashore. it was the pacific ocean!