Kinds of Drains. 391 



made by laying bundles of twigs in the bottom of the ditch 

 and covering them, expecting the water to trickle through 

 the passageways left. In other cases two or three round 

 poles were covered in the bottom of the ditch or two slabs 

 were laid edge to edge with their round sides down. Two 

 boards were sometimes set on edge Y-shaped, with opening 

 down. 



More permanent closed drains were made by filling the 

 bottom of the ditch with cobblestone, by setting flat stone 

 on edge Y-shape, by setting two lines of stone on edge and 

 covering with flat stone and even by using four stone for 

 top, bottom and sides. In other cases brick were used in 

 place of stone and some even made tile out of blocks of peat, 

 cutting semi-cylindrical cavities in the faces of square 

 blocks of peat, then laying these together to form the water- 

 way. Most of these devices, however, must be looked upon 

 as makeshifts rather than as permanent improvements, and 

 have largely gone out of use. 



The modern tile, made of hard burned clay, is cylindrical 

 in form and usually in 1-foot lengths with diameters rang- 

 ing from 2 to 12 or more inches. 



362. Essential Features of Drain Tile A good drain tile 

 should be hard burned, giving a clear ring when struck. 

 It is much more important to have them hard burned and 

 strong than it is to have them open and porous. Soft 

 burned tile which give little or no ring when struck are 

 much more liable to crumble down under the action of 

 frost. We have visited one field drained with soft burned 

 tile laid 2.5 to 3.5 feet deep and, in less than five years after 

 laying, holes appeared in the field in many places. On 

 digging in these places it was found that the tile had 

 crumbled into small chips, caused by freezing. 



Tile are sometimes made from clay containing pebbles 

 of limestone which when burned are converted into lima 

 These lumps of lime bedded in the tile slack as soon as 

 water enough reaches them and by their expansion the tile 



