The following figures represent very perfect arrangements of this kind, in actual use. [Illustration: Figs. 41 & 42.--WELL WITH SILT BASIN, OR TRAP, AND COVER.] The flap attached to a chain at A, is designed to close the incoming drain, so as to keep back the water, and thus flush the drain, as it is termed, by filling it with water, and then suddenly releasing it. It is found that by this process, obstructions by sand, and by per-oxide of iron, may be brought down from the drains, when the flow is usually feeble. SMALL WELLS, OR PEEP-HOLES. By the significant, though not very elegant name of peep-holes, are meant openings at junctions, or other convenient points, for watching the pulsations of our subterranean arteries. In addition to the large structures of wells and traps, such as have been represented, we need small and cheap arrangements, by which we may satisfy ourselves and our questioning friends and neighbors, that every part of our buried treasure, is steadily earning its usury. It is really gratifying to be able to allow those who "don't see how water can get into the tiles," and who inquire so distrustfully whether you "don't think that land on the hill would be just as dry without the drains," to satisfy themselves, by actually seeing, that there is a liberal flow through all the pipes, even in the now dry soil. And then, again, "The best laid schemes o' mice an' men Gang aft agley." and drains will get obstructed, by one or other of the various means suggested in another place. It is then convenient to be able to ascertain with certainty, and at once, the locality of the difficulty, and this may be done by means of peep-holes. These may be formed of cast iron, or of well-burnt clay, or what is called stone-ware, of 4, 6, or 10 inches internal diameter, and long enough to reach from the bottom of the drain to the surface, or a little above it. The drain or drains, coming into this little well, should enter a few inches above the pipe which carries off the water, so that the incoming stream may be plainly seen. A strong cover should be fitted to the top, and secured so as not to cause injury to cattle at work or feeding on the land. The arrangement will be at once seen by a sketch given on the following page. [Illustration: Figs. 43 & 44.--SMALL WELL, OR PEEP-HOLE, AND COVER.] In our own fields, we have adopted several expedients to attain this object of convenient inspection. In one case, where we have a sub-main, which receives the small drains of an acre of orchard, laid at nearly five feet depth, we sunk two 40-gallon oil casks, one upon the other, at the junction of this sub-main with another, and fitted upon the top a strong wooden cover. The objections to this contrivance are, that it is temporary; that it occupies too much room; and that it is more expensive than a well of cast iron or stone-ware of proper size.