Ko. 4.] DRAINAGE. 375 



exclude sand and silt. Stone drains are, therefore, more likely to be- 

 come clogged in most soils than tile drains. 



4, Because of the nature of the material used the stone drain in- 

 evitably presents rougher surfaces to the passage of water, and any 

 obstructions which enter the drain are therefore more likely to remain 

 in it. 



Because of these reasons it is not believed that it will usually be wise 

 to put in stone drains. The only saving is the outlay required for the 

 purchase of the tiles, and this saving will in most cases be much more 

 than offset by the extra costs of putting in which have been referred to. 

 Stone drains will prove most durable in soils of heavy and compact 

 character, because in these soils they will be less likely to fill with silt 

 and sand. In such soils, where stones of suitable character are avail- 

 able for drain construction, it may possibly sometimes pay to put in 

 stone drains, although even this is open to question. 



Tile Drains. — Drainage by means of tile made especially for the 

 purpose is practically the only system of thorough underdrainagc that 

 can in most cases be advised. Tile drains are better than drains of any 

 other kind for many reasons, most prominent among which are the 

 following : — 



1. On account of their regular form they offer a smoother and more 

 uniform conduit for water, and are, therefore, less liable to obstruction 

 than drains made of any other material. 



2. Closer joints can be made than in most other kinds of under- 

 drains, and the probability of entrance of silt and fine sand is therefore 

 less. 



3. The material is practically imperishable if placed below the reach 

 of frost. 



Kinds of Tiles. 

 Numerous forms of drain tiles are offered in our market. It is be- 

 lieved that choice will lie between two of these, viz., the round, and 

 the six or eight sided. In both of these kinds of tile the bore is round, 

 and if made of equally good clay and well burned there is probably no 

 great difference between them in respect to cost, convenience of laying 

 and durability. As found in our markets, however, the six or eight 

 sided tiles appear to be lighter in proportion to capacity than the 

 round. This, of course, is an advantage in connection with transpor- 

 tation. It might be thought that the six and eight sided tiles, having 

 flat faces, may be more conveniently laid than the round, which when 

 placed upon a flat surface are more likely to roll. A highly convenient 

 method, however, of preparing the bottom of a ditch for tiles is the 

 cutting of a half-circle groove. Only this groove, which is to receive 

 the round tile, needs to be graded with care and absolute exactness, 

 and if the round tile be laid in such a groove the difficulty referred to 

 is not experienced. Whatever the kind of tile selected the individual 

 pieces should be straight, and the ends should be as square and true 

 as possible. The tile should be hard-burned. 



