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.