CHAPTER VI.
DRAINAGE WITH TILES.
What are Drain-Tiles?--Forms of Tiles.--Pipes.--Horse-shoe Tiles.--Sole-Tiles.--Form of Water-Passage.--Collars and their Use.--Size of Pipes.--Velocity.--Friction.--Discharge of Water through Pipes.--Tables of Capacity.--How Water enters Tiles.--Deep Drains run soonest and longest.--Pressure of Water on Pipes.--Durability of Tile Drains.--Drain-Bricks 100 years old.