That these are not mere speculations of our own, may be seen from extracts which will be given from answers returned by distinguished observers of these matters in England and Scotland, to a question proposed to them as to the actual effects produced by extensive drainage. Some diversity of opinion is observable in the different replies, which were made, independently in writing, and so are more valuable. _Mr. Smith._--"During dry periods, more particularly in Summer, the water in the streams is greatly lessened by thorough-draining; for there is so great a mass of comparatively dry and absorbent soil to receive the rain, that Summer showers, unless very heavy and continuous, will be entirely absorbed." _Mr. Parkes._--"The intention and effect of a complete and systematic under-drainage is the liberation of the water of rain more quickly from the land than if it were not drained; and therefore the natural vents, or rivers, very generally require enlargement or deepening, in order to pass off the drainage water in sufficiently quick time, and so as to avoid flooding lower lands. "The sluggish rivers of the midland and southern counties of England especially, oppose great obstacles to land-drainage, being usually full to the banks, or nearly so, and converted into a series of ponds, by mill-dams erected at a few miles distance below each other; so that, frequently, no effectual drainage of the richest alluvial soil composing the meadows, can be made, without forming embankments, or by pumping, or by resort to other artificial and expensive means. "The greater number of the corn and other water-mills throughout England ought to be demolished, for the advantage of agriculture, and steam-power should to be provided for the millers. I believe that such an arrangement would, in most cases, prove to be economical both to the landholder and the miller. "Every old authority, and all modern writers on land drainage in England, have condemned water-mills and mill-dams: and if all the rivers of England were surveyed from the sea to their source, the mills upon them valued, the extent of land injured or benefitted by such mill-dams ascertained, and the whole question of advantage or injury done to the land-owner appreciated and appraised, I have little doubt but that the injury done, would be found so greatly to exceed the rental of the mills, deduction being made of the cost of maintaining them, that it would be a measure of national economy, to buy up the mills, and give the millers steam-power."