144 



LAND DRAINAGE 



190. Finishing the outlet. The outlet of the main 

 should be completed with two objects in view : 



1. Provision should be made against its destruction 

 by frost, flood, tramping of live-stock, and the like. 



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FIG. 57. Showing the way in which bolts may be imbedded in the 

 concrete or other outlet protection by which strips of wood may be 

 bolted in place to carry screen to protect mouth of outlet from vermin, 

 etc. This shows piece of screen nailed over the outlet. The width 

 of face of outlet will depend much upon the nature of the soil, 

 height, and slope. The face in this figure is but 18 inches wide. 

 Ordinarily the face proper should probably range from 30 to 60 

 inches. 



2. Usually it is best to replace the lower 8 to 12 feet 

 of tile with glazed sewer pipe, or with a piece of cast- 

 iron pipe of proper size. (See Fig. 55.) This should be 

 done, of course, when the work of laying the tile begins. 



