DRAINAGE 



207 



Figure 97. Mason's level. 



&\ 



lay the tiles with the tile hook, as shown at K, Figure 94. 



By exercising a little dexterity, the tiles can be placed, 



and even revolved on 



the hook, so as to make 



the unions fairly tight. 



There is rarely danger 



of having the ends too 



close together, as a 



very narrow opening will allow the water to enter. As 



soon as the tiles are laid, they should be covered with a 



few inches of earth and tramped so that they will not 



be displaced. If the earth 

 forming the side of the 

 ditch is not fine sand, or 

 if it has sufficient clay in 

 it to bind well, sufficient 

 to pack about the tiles 

 can be cut loose with the 

 spade by the workman 

 standing in the ditch and 

 tramped firmly about the 

 tiles. 



Where the branches 

 lead off from the line of 

 the ditch, the unions 

 should be carefully made. 

 Union tiles, as shown in 

 Figures 75 and 77, 

 are used for this pur- 

 pose. Where these are 

 not available, as in case 

 of breakage or long dis- 

 tance from factory, unions 

 can be made by cutting 

 tile on the main line and 



fitting to this hole the end of a tile on the branch line. 



3" 



Figure 98. Shows the manner of marking the 

 upright of Figure 96 so that the holes may be 

 bored at the desired distance apart. A horizon- 

 tal line is drawn through the center of the hole 

 which supports the top board when it is par- 

 allel to the bottom board, and another at each 

 Inch further down for several inches. Then each 

 inch is divided into three equal parts by lines 

 and three vertical lines are drawn an inch or 

 more apart. By boring a hole at each inter- 

 section, the holes are made at intervals of one- 

 third of an inch apart, sufficient to give an added 

 rise in the grade of 2 inches per 100 feet, the 

 bottom board being 16% feet long. 



a hole with a cold chisel in a 



