DRAINAGE. 



101 



, , . , , Jb I Ab I Jb I 

 ./ff3, etc; and their laterals —7—,-^—, — ^i etc., until the 



stakes of all the drains are so marked as to be clearly designated. 



(See map, Fig. 30.) 



Fig. JO. 



Map of a ten-acre field, showing the conformation of the land; the arrangement of the drains and silt- 

 basins J and the method of marking the stakes. Scale 160 feet to I inch. 



