But of all these agencies no one has awakened so general an interest in agriculture as the appointment of Arbor Day, by governors of states, by legislatures, and by state, county and town superintendents of schools. The plan of Arbor Day is simple and inexpensive, and hence the more readily adopted and widely effective. In some states the work has been well done without any legislation. The best results, however, are secured when an act is passed requesting the Governor, each spring, to recommend the observance of Arbor Day, by a special message. The chief magistrate of the state thus most effectually calls the attention of all the people to its importance, and secures general and concerted action. _How_ forests conserve the water supplies and lessen floods is aside from the topic of this paper. While the fact of the increase of spring freshets is everywhere admitted, and scientists agree as to the cause, the popular disbelief of the true theory is the great hindrance to remedial action. The bills for the protection of the Adirondack forests, in the legislature of New York, in 1884, failed by reason of the opposition of the lumbermen, and the common doubt and denial of the benefits of forests in the conservation of the rainfall. I often met the same skepticism in the Ohio valley, even among the sufferers from the flood disasters. They were attributed to the extensive use of tile drains. But both in 1883 and 1884, these floods occurred when the ground was frozen deep, and the drains were therefore inoperative. That so simple a cause as forest denudation should produce such disastrous results seems at first incredible. It is only when the vast areas contributing to a single river are considered, that the proof of the forest theory seems clear. Take the Ohio River, for illustration. The area drained by it is 214,000 square miles, or twenty-two times as much as that which in Vermont, New Hampshire, Massachusetts and Connecticut is drained by the Connecticut River; an area which includes portions of New York, Pennsylvania, Ohio, Indiana, Illinois, West Virginia, Virginia, North Carolina, Georgia, Alabama, Mississippi, Tennessee, and Kentucky. The length of the Ohio is about 1,000 miles, and that of its ten leading tributaries nearly 4,000, and that of the many minor affluents as much more. The smallest influences working over such immense regions, and ultimately combining in one stream, may enormously swell its volume. As the destruction of forests has been going on for centuries, the remedy must be the work of time, for it must include slow processes and agencies, each _separately_ minute, which become important when multiplied by myriads and extended over broad areas. Arbor Day has proved such an agency.