To those not familiar with the topography of the city, it should be stated that it is separated by the Chicago River, a slow, narrow stream, into three main divisions, known as the south, the north, and the west side.

By a triumph of engineering, the former mouth of this river at the lake is now its source, the main stream being turned back upon itself, and dividing into two branches at a point a little over half a mile from the lake, one flowing to the southwest into the Illinois, and the other from the northwest into the main stream.

The south division includes all the territory bounded on the east by the lake, on the north by the main river and on the west by the south branch. The north division includes the area bounded on the east by the lake, on the south by the main river, and on the west by the north branch, while the west division embraces all that part of the city west of the two branches. The fire originated in De Koven Street, the southeastern part of the west side, and it was carried steadily to the north and east by an increasing gale. The south side, with all its magnificent buildings, was soon directly in the line of the fire.

When Dennis saw that the flames had crossed the south branch, and were burning furiously beyond, he knew that the best part of the city was threatened with destruction. He hastened to the Washington Street tunnel, where he found a vast throng, carrying all sorts of burdens, rushing either way. He plunged in with the rest, and soon found himself hustled hither and thither by a surging mass of humanity. A little piping voice that seemed under his feet cried: "O mamma! mamma! Where are you? I'm gettin' lost."

"Here I am, my child," answered a voice some steps in advance and Dennis saw a lady carrying another child; but the rushing tide would not let her wait—all, in the place where they were wedged, being carried right along. Stooping down, he put the little girl on his shoulder where she could see her mother, and so they pressed on. Suddenly, in the very midst of the tunnel, the gas ceased, by reason of the destruction of the works, and utter darkness filled the place.

There was a loud cry of consternation, and then a momentary and dreadful silence, which would have been the preface of a fatal panic, had not Dennis cried out, in a ringing voice, "All keep to the right!"

This cry was taken up and repeated on every hand, and side by side, to right and left, the two living streams of humanity, with steady tramp! tramp! rushed past each other.

When they emerged into the glare of the south side Dennis gave the child to its mother and said, "Madam, your only chance is to escape in that direction," pointing northwest.

He then tried to make his way to the hotel where Professor and Mrs. Leonard were staying, but it was in the midst of an unapproachable sea of fire. If they had not escaped some little time before, they had already perished. He then tried to make his way to the windward toward his own room. His two thousand dollars and all his possessions were there, and the instinct of self-preservation caused him to think it was time to look after his own. But progress was now very difficult. The streets were choked by drays, carriages, furniture, trunks, and every degree and condition of humanity. Besides, his steps were often stayed by thrilling scenes and the need of a helping hand. In order to make his way faster he took a street nearer the fire, from which the people had mostly been driven. As he was hurrying along with his hat drawn over his eyes to avoid the sparks that were driven about like fiery hail, he suddenly heard a piercing shriek. Looking up he saw the figure of a woman at the third story window of a fine mansion that was already burning, though not so rapidly as those in the direct line of the fire. He with a number of others stopped at the sound.

"Who will volunteer with me to save that woman?" cried he.