Page:The American Cyclopædia (1879) Volume VI.djvu/249

 DRAINAGE tially filled with stones small enough to pass through a three-inch ring, were covered over with soil. At the bottom a main drain was constructed, generally in stone work or with tiles. The new practice met with great opposi- tion from the advocates of Elkington's method, but finally came to be regarded as the only complete system applicable in all cases. In some instances the other plan may no doubt be economically adopted. The drains came at last to be made chiefly of tiles, for the manu- facture of which the first machine was invent- ed by the marquis of Tweeddale. The prac- tice has been successfully introduced into the United States, and drain tiles are now a con- siderable branch of manufacture. Wet lands are well known to be unfavorable to the pro- duction of large crops; it is also true that grains, potatoes, grass, &c., are sounder and better when raised upon lands not subject to excess of moisture. The soils that retain it are correctly described as cold, while the more porous soils are called warm. From the ex- periments of Mr. Parkes in a bog in Lancashire, it appears that by giving free passage to the water through a cold soil by thorough drain- age, its temperature at the depth of seven inches may be raised 10 above that of un- drained adjoining land of the same quality. Thus drainage produces the effect of a warmer climate, and may add in fact many days to the season ; and this not merely by reason of the warmth extended for a longer period, but in the spring the soil is sooner prepared for cul- tivation, and may be in condition for plough- ing and planting even two weeks before neigh- boring land of similar quality in other respects would admit of working. While frequent ac- cession of water is a great benefit to lands through which it finds a ready passage, its re- tention impairs in various ways the fertility of the soil. It prevents the pulverization of the earth by the plough and harrow, and the cir- culation of air to the roots of the plants.. It nourishes a growth of noxious plants, and in woodlands its injurious effect is seen in the pro- duction of many lichens, fungi, and other para- sites upon the trees. Open ditches may be made in the lower grounds, where natural streams are not convenient for receiving the drainage from the underground ditches, which are made by laying tiles in trenches and cover- ing them with soil. A section of an under- ground drain is represented in fig. 1. Some- times coarse stones are used, but tiles are pref- erable on account of their less liability to be- come clogged. Several kinds of tile are made, each being suitable under certain circum- stances. They are from 3 to 10 in. in diameter, and from 1 to 2 ft. in length. They are made of nearly the same kind of clay as brick, and are baked sufficiently to include as much po- rosity and toughness as possible. The different forms generally in use are represented in fig. 2. Any variety may be large or small. The horseshoe tile may be laid upon flagging or boards, and all of them should be placed deep, out of the way of frost and the plough. In Europe the largest draining operations have been those for reclaiming immense tracts FIG. 1. Section of an Under- FIG. 2. a. Pipe tile. 5. Sole ground Drain. tile. c. Horseshoe tile. of submerged or boggy lands, some of which were altogether below the level of natural drainage. As early as 1436 attention was di- rected in England to the possibility of reclaim- ing the fens bordering the river Ouse and its tributaries, now known as the Bedford Level. These covered an area of about 400,000 acres, which in ancient times appears to have been in a condition for cultivation. The tract pre- sents but very limited natural channels for conveying the water into the sea on the north- east. The attempt to embank and deepen these in the 15th century was unsuccessful, but it was renewed by the earl of Bedford in 1634. In three years he expended 100,000 in embankments for keeping out the waters of the rivers, and removing those within by pumping. This attempt also failed; but in 1649 his son recommenced operations, and succeeded after an expenditure of 300,000 more. From that time the lands reclaimed have been kept free from water by machinery worked by wind- mills. Among the numerous drainage chan- nels cut through these lands are two nearly parallel, more than 20 m. in length, and both navigable, serving to cut off a long circuitous reach of the river Ouse. By other direct chan- nels made during the present century above the outlet of the same river, and also of the neighboring river Nene, many thousand acres more have been reclaimed. The steam engine has been advantageously substituted in many instances for the windmills ; and it has been found practicable to estimate closely the power and expense required to keep an area of given extent thoroughly drained. The annual fall of rain averaging 26 in., there would be, with a very moderate allowance for evaporation, 2 in. per month of water to be raised, or 1-J- cubic feet of water as a maximum on every square yard of surface. The amount on an acre, 7,260 cubic feet, may be raised 10 ft. and discharged in about 2 hours and 10 minutes by the power of one horse. A steam engine of 10-horse power could then each month raise to the same height and discharge the water from 1,000 acres in 232 hours. The drainage of Haarlem lake in Holland, undertaken in 1839, was a gigantic