VI CONTENTS. 



PAGE 



Base — Watercourse as Base— Method by Central Base Line — 

 Record of the Work — Topography by Contour Lines— Practical 

 Hints 52 



CHAPTER V. 



LAYING OUT DRAINS IN THE FIELD. 



Staking Out Drains — Designating Drains — Levelling Drains and 

 Keeping the Notes — Notes for Platting — A Common Datum — 

 The Profile — Compass Surveying for Drainage Work —Keeping 

 Compass Notes *ji 



CHAPTER VI. 



FIXING THE GRADE OF DRAINS. 



Grade of Drains — Depth of Drains — Frequency of Drains— Prelimi- 

 nary Estimate of Length of Drains. 85 



CHAPTER VII. 



MAPS AND RECORDS. 



Drafting Instruments —Platting Compass Notes and Angles — 



Making the Map— Copying Maps * . . . 95 



CHAPTER Vin. 



GRADING THE DITCHES FOR TILE. 



Digging Ditches and Laying the Tile— Difficulties in Constructing 

 Tile Drains — Inspecting Tile Drains— Filling the Ditches — 

 Marking Out Tile-ditches with the Plow— Outlet Protection — 

 The Silt-basin— Digging Tile ditches with Machines— Contracts 

 for Construction of Tile Drains 103 



CHAPTER IX. 



FLOW OF WATER THROUGH PIPES. 



Formulas for Flow— Flow of Water through Tile Drains— Applica- 

 tion ol the Formul.i— Examples of the Use ot the Formula — 

 Limitations of Size, Grade, and Length of Drain ,,,.... 12^ 



