CONSTRUCTION 147 



the depth of the main at the point of connection. (See 

 paragraphs 197-199.) This fact may modify both the 

 grade and the general depth of the lateral. 



195. Making provision for lateral outlet when laying 

 the main. As the digging of the main proceeds, and 

 as the tile are laid, provision should be made for the outlet 



FIG. 59. Five-inch tile with small opening, and hammer used in mak- 

 ing the opening. 



of each lateral. The connection should be introduced 

 and an obstruction placed over the outer end till the laying 

 of the lateral is begun. 



196. Joining laterals to mains. Mention has already 

 been made of the angle at which the laterals should be 

 brought to the main. Three general methods of making 

 connections are suggested ; namely, side, top, and angle 

 connection. 



197. Side connection. By the first method the lateral 

 discharges into the side of the main. In this case the 

 center of the lateral should come even with the center of 

 the main. This means that if the lateral has a smaller 



