"We will assume the drain to be four feet deep, and the water-table to be at one foot below the surface of the earth. Every particle of water which lies at three feet below the water-table, has on it the pressure of a column of water three feet high. This pressure will drive the particle in any direction in which it finds no resistance, with a rapidity varying inversely to the friction of the medium through which the column acts. The bottom of our drains will offer no resistance, and into it particles of water will be pushed, in conformity with the rule we have stated; rapidly, if the medium opposes little friction; slowly, if it opposes much. The water so pushed in runs off by the drain, the column of pressure being diminished in proportion to the water which runs off." Mr. Thomas Arkell, in a paper read before the Society of Arts, in 1855, says, on this point: "The pressure due to a head of water of four or five feet, may be imagined from the force with which water will come through the crevices of a hatch, with that depth of water above it. Now, there is the same pressure of water to enter the vacuum in the pipe-drain, as there is against the hatches, supposing the land to be full to the surface." We do not find any intimation that there is any error in the view advanced by the learned gentleman quoted; and if there is none, we have an explanation of the faculty which water seems to have, of finding its way into drainpipes. Yet, we feel bound to confess, that, aside from authority, we should have supposed that the pressure due to a column of pure water, would be essentially lessened, by the interposition of solid matter between its particles. CHAPTER XX. EFFECT OF DRAINAGE ON STREAMS AND RIVERS. Drainage Hastens the Supply to the Streams, and thus Creates Freshets.--Effect of Drainage on Meadows below; on Water Privileges.--Conflict of Manufacturing and Agricultural Interests.--English Opinions and Facts.--Uses of Drainage Water.--Irrigation.--Drainage Water for Stock.--How used by Mr. Mechi. The effect of drainage upon streams and rivers, has, perhaps, little to interest merely practical men, in this country, at present; but the time will soon arrive, when mill-owners and land-owners will be compelled to investigate the subject. Men unaccustomed to minute investigation, are slow to appreciate the great effects produced by apparently small causes; and it may seem to many, that the operations of drainage for agriculture, are too insignificant in their details, perceptibly to affect the flow of mill-streams and rivers. A moment's thought will convince the most skeptical, that the thorough-drainage of the wet lands, even of a New England township, must produce sensible effects upon the streams which convey its surplus water toward the sea.