Most peat meadows, in New England, when first relieved of stagnant water, are very light and spongy. The soil is filled with acids which require to be neutralized by an application of lime, or what is cheaper and equally effectual, by exposure to the atmosphere. These soils, when the water is suddenly drawn out of them, retain their bulk for a time, and are too porous and unsubstantial for cultivation. A season or two will cure this evil, in many cases. The soil will become more compact, and will often settle down many inches. It is necessary to bear this in mind in adjusting the drains, because a four-foot drain, when laid, may, by the mere subsidence of the land, become a three-foot drain. A hasty judgment, in any case, that the land is over-drained, should be suspended until the soil has acquired compactness by its own weight, and by the ameliorating effect of culture and the elements. Mr. Denton, alluding to the opinion of "many intelligent men, that low meadow-land should be treated differently to upland pasture, and upland pasture differently to arable land," says, "My own observations bring me to the conclusion, that it is not possible to lay pasture-land too dry; for I have invariably remarked, during the recent dry Summer and Autumn particularly, that both in lowland meadows, and upland pastures, those lands which have been most thoroughly drained by deep and frequent drains, are those that have preserved the freshest and most profitable herbage." While, therefore, we have much doubt whether any land, high or low, can be over-drained for general cultivation, it is probable that a less expensive mode of drainage may be sometimes expedient for grass alone. While we believe that, in general, even peat soils may be safely drained to the same depth with other soil, there seems to be a well-founded opinion that they may frequently be rendered productive by a less thorough system. The only safety for us, is in careful experiment with our own lands, which vary so much in character and location, that no precise rules can be prescribed for their treatment. CHAPTER XVIII. OBSTRUCTION OF DRAINS. Tiles will fill up, unless well laid.--Obstruction by Sand or Silt.--Obstructions at the Outlet from Frogs, Moles, Action of Frost, and Cattle.--Obstruction by Roots.--Willow, Ash, &c., Trees capricious.--Roots enter Perennial Streams.--Obstruction by Mangold Wurtzel.--Obstruction by Per-Oxide of Iron.--How Prevented--Obstruction by the Joints Filling.--No Danger with Two-Inch Pipes.--Water through the Pores.--Collars.--How to Detect Obstructions. But won't these tiles get filled up and stopped? asks almost every inquirer on the subject of tile draining.