Page:Popular Science Monthly Volume 38.djvu/767

Rh A physical history of the Ohio River would not be complete without a mention of the great variation in volume it presents, and some mention of the probable causes. Nothing is definitely known of its fluctuations during the prehistoric period, or indeed previous to 1832. It is true there are traditions of great floods in the river as far back as 1774. In 1787 there was a flood which some authors state reached one hundred and twelve feet. In 1792 there was another, reaching the height of sixty feet. The flood of 1832, of which there is authentic record, attained a height of sixty-four feet three inches. There were, up to 1883, twelve floods which reached or exceeded fifty feet. In that year (1883) the water reached a height of sixty-six feet four inches; and this was exceeded the following year by a volume of water which marked upon the gauge at the Cincinnati Water-Works seventy-one feet, three fourths of an inch. During the year 1890 the water twice reached a depth exceeding fifty feet.

Contrast these great floods with the extreme low water sometimes experienced. Five times during fifty years has the water sunk so low as to leave but three feet in the channel. The lowest ever known was in September, 1881, when the records show that twenty-three inches of water were found where three years later there were seventy-one feet. In October, 1887, it was also very low, there then being but two feet eight inches in the channel. At that time the river in front of Cincinnati showed its hidden dangers as scarcely ever before. A boy four feet high might have waded across without wetting his suspender-buttons. "Ugly-looking black bowlders, long, narrow, jagged reefs of moss-and slime-covered rocks and hillocks of gravel uplift their heads three, four, and five feet above the surface of the stream, all along the channel between the railroad and suspension bridges, while the big bar at the mouth of the Licking thrusts itself sheer across the river to within a hundred feet of the Ohio edge, at the foot of Walnut Street. One pebbled and coal-strewn reef, between Walnut and Vine Streets, is exposed for over two hundred feet, and it can be reached by wading from either shore. A sunken barge, which for years has been concealed from sight by the waters, is now wholly exposed, and its skeleton is visible from keel to gunwales, and stem to stern."

The cause of such fluctuations is not far to seek. The destruction of forests about the head-waters of the tributaries, large and small, prevents the conservation of the water which falls in a rainy season. It rushes in torrents down the denuded hills and mountains, and is gone in a few days. A smaller amount of rain than the average, and the river becomes abnormally low. Abundant precipitation, on the other hand, combined with such