We should not expect that, on such a clay, the full effect of drainage would be at once apparent. The water falling on the surface would very slowly find its way downward, at first. But after the heat of Summer, aided by the drains underneath, had contracted and cracked the soil, passages for the water would soon be found, and, after a few years, the whole mass, to the depth of the drains, would become open and permeable. As an old English farmer said of his drains, "They do better year by year; the water gets a habit of coming to them." Although this be not philosophical language, yet the fact is correctly stated. Water tends towards the lowest openings. A deep well often diverts the underground stream from a shallower well, and lays it dry. A single railroad cut sometimes draws off the supply of water from a whole neighborhood. Passages thus formed are enlarged by the pressure of the water, and new ones are opened by the causes already suggested, till the drainage becomes perfect for all practical purposes. So much is this cracking process relied on to facilitate drainage, that skillful drainers frequently leave their ditches partly open, after laying the tiles, that the heat may produce the more effect during the first season. As to the depth of drains in stiff clays, enough has already been said, under the appropriate title. In England, the weight of authority is in favor of four-foot drains. In this country, a less depth has thus far, in general, been adopted in practice, but it is believed that this has been because a greater depth has not been tried. It is understood, that the most successful drainers in the State of New York, have been satisfied with three-foot drains, not, as it is believed, because there is any instance on record, in this country, of the failure of four-foot drains, but because the effect of more shallow drains has been so satisfactory, that it has been thought a useless expense to go deeper. To Mr. Johnston and to Mr. Delafield, of Seneca County, the country is greatly indebted for their enterprise and leadership in the matter of drainage. Mr. Johnston gives it as his opinion, that "three feet is deep enough, if the bottom is hard enough to lay tiles on; if not, go deeper." Without intimating that any different mode of drainage than that adopted, would have been better on Mr. Johnston's farm, we should be unwilling to surrender, even to the opinion of Mr. Johnston and his friends, our conviction that, in general, three-foot drains are too shallow. Mr. Johnston expressly disclaims any experience in draining a proper clay soil. In the _Country Gentleman_, of June 10th, 1848, he says: