170 



FARM DEVELOPMENT 



is the quality of scaling or crumbling-. The presence 

 of lumps or flakes of lime which will slack when wet, 

 causes tiles to disintegrate and become worthless. Ques- 

 tionable tiles may be tested by placing them where they 



can be partially 

 covered by 

 water during 

 winter and al- 

 lowed to freeze 

 and thaw re- 

 peatedly. Tiles 

 that crumble 

 by springtime 

 when treated 

 in this manner 

 are not suited 

 to tile draining, 

 especially in a 

 cold climate. 

 The best 



Figure 72. System of tile drains OB a 160-acre farm. j , -i 



thoroughly vitrified throughout, showing that there has 

 been some fusing or melting of the clay under the in- 

 tense heat of the kiln. Many manufacturers glaze their 

 tiles, just as the old-fashioned stone milk crock was 

 glazed, by placing salt in the kiln. If the tile is properly 

 burned, glazing adds little or nothing to its value, though 

 the cost is inconsiderable. The fear entertained by some 

 that glazing retards the flow of water through the sub- 

 stance of the tile into the drain tile, is not well founded. 

 Little water goes through the body of any properly made 

 drain tile. There is ample room for the water to seep 

 through between the ends of the tiles, and practically all 

 of it enters at these places. It is also proven that nearly 

 all the water enters the tile at the lower half of the 



