The engineer, it is
true, had given the course, and in doing so had taken into account
the altitude necessary to clear the summits of the high lands in the
district. But as the aeronef was rapidly nearing a mountainous
country, it was only prudent to keep a good lookout, in case some
slight deviation from the course became necessary.

Looking at the country beneath them, Uncle Prudent and Phil Evans
noticed a large lake, whose lower southern end the "Albatross" had
just reached. They concluded, therefore, that during the night the
whole length of Lake Erie had been traversed, and that, as they were
going due west, they would soon be over Lake Michigan. "There can be
no doubt of it," said Phil Evans, "and that group of roofs on the
horizon is Chicago."

He was right. It was indeed the city from which the seventeen
railways diverge, the Queen of the West, the vast reservoir into
which flow the products of Indiana, Ohio, Wisconsin, Missouri, and
all the States which form the western half of the Union.

Uncle Prudent, through an excellent telescope he had found in his
cabin, easily recognized the principal buildings. His colleague
pointed out to him the churches and public edifices, the numerous
"elevators" or mechanical, granaries, and the huge Sherman Hotel,
whose windows seemed like a hundred glittering points on each of its
faces.

"If that is Chicago," said Uncle Prudent, "it is obvious that we are
going farther west than is convenient for us if we are to return to
our starting-place."

And, in fact, the "Albatross" was traveling in a straight line from
the Pennsylvania capital.

But if Uncle Prudent wished to ask Robur to take him eastwards he
could not then do so. That morning the engineer did not leave his
cabin. Either he was occupied in some work, or else he was asleep,
and the two colleagues sat down to breakfast without seeing him.

The speed was the same as that during last evening. The wind being
easterly the rate was not interfered with at all, and as the
thermometer only falls a degree centigrade for every seventy meters
of elevation the temperature was not insupportable. And so, in
chatting and thinking and waiting for the engineer, Uncle Prudent and
Phil Evans walked about beneath the forest of screws, whose gyratory
movement gave their arms the appearance of semi-diaphanous disks.

The State of Illinois was left by its northern frontier in less than
two hours and a half; and they crossed the F