376 BOARD OF AGRICULTURE. [Pub. Doc. 



of draining larger areas of level lands to an outfall of limited 

 depth. 



They are easily examined (through silt-wells), and imper- 

 fections or stoppages may be thus approximately located for 

 repair or removal. 



They are more durable, and, properly laid and cared for, 

 are practically permanent in their life and operation. 



There is a popular impression that ground water enters a 

 tile drain through the porous bodies of the tiles themselves. 

 This is essentially wrong. Indeed, the best tiles are those 

 that are uniformly hard-burned to such a degree (just short 

 of vitrification) that nearly all physical porosity has dis- 

 appeared. In point of fact, at all times, excepting when 

 the amount of water seeking to enter a drain exceeds its 

 maximum capacity when running full, the water enters at 

 the bottom of the joints and at the sides, as far up only as 

 the surface of the stream flowing in and through the drain. 

 One should not be tempted, therefore, to purchase tile for 

 which is claimed the virtue of admitting water through the 

 porous material comprising them, as such porosity serves 

 no practical purpose, and can result only from insufficient 

 burning, with consequent want of durability. 



The joints of any land tile (however acciVrately moulded, 

 however well their shape may be retained in the process of 

 burning, and however closely fitted in laying) afford not only 

 ample but practically the sole means for the admission of 

 water from the soil around them. Indeed, the key to suc- 

 cess in tile drainage, after securing a suitable outfall and 

 adequate grades leading down thereto, lies in making such 

 close-fitting and well-protected joints at the abutting ends 

 of the tiles that clay and fine sand cannot be carried into the 

 drain by the water as it enters through the joints. The sub- 

 soils of lands which best repay drainage are usually com- 

 posed so largely of clay, or of very fine sand with or without 

 a clay admixture, that not even the closest joints that can be 

 made are thin or close enough, without special protection, 

 to prevent some silt being carried into the drain, whence it 

 becomes necessary to provide further means to prevent the 

 entrance of such particles. This is usually done by laying 



