"Each, drain emptied itself through a fence bank into a running stream in a road below it; the discharge therefore was distinctly observable. Two or three of the pipes had now ceased running; and, with the exception of one which tapped a small spring and gave a stream about the size of a tobacco pipe, the run from the others did not exceed the size of a wheat straw. The greatest flow had been observed by Mr. Hammond at no time to exceed half the bore of the pipes. The fall in this field is very great, and the drains are laid in the direction of the fall, which has always been the practice in this district. The issuing water was transparently clear; and Mr. Hammond states that he has never observed cloudiness, except for a short time after very heavy flushes of rain, when the drains are quickly cleared of all sediment, in consequence of the velocity and force of the water passing through so small a channel. Infiltration through the soil and into the pipes, must, in this case, be considered to have been perfect; and their observed action is the more determinate and valuable as regards time and effect, as the land was saturated with moisture previous to this particular fall of rain, and the pipes had ceased to run when it commenced. This piece had, previous to its drainage, necessarily been cultivated in narrow stretches, with an open water furrow between them; but it was now laid quite plain, by which one-eighth of the continuation of acreage has been saved. Not, however, being confident as to the soil having already become so porous as to dispense entirely with surface drains, Mr. Hammond had drawn two long water furrows diagonally across the field. On examining these, it appeared that very little water had flowed along any part of them during these 12 hours of rain,—no water had escaped at their outfall; the entire body of rain had permeated the mass of the bed, and passed off through the inch pipes; no water perceptible on the surface, which used to carry it throughout. The subsoil is a brick clay, but it appears to crack very rapidly by shrinkage consequent to drainage." *Obstructions.*—The danger that drains will become obstructed, if not properly laid out and properly made, is very great, and the cost of removing the obstructions, (often requiring whole lines to be taken up, washed, and relaid with the extra care that is required in working in old and soft lines,) is often greater than the original cost of the improvement. Consequently, the possibility of tile drains becoming stopped up should be fully considered at the outset, and every precaution should be taken to prevent so disastrous a result. The principal causes of obstruction are _silt, vermin_, and _roots_.