CHAPTER VIII.. Arrangement of Drains.

ARRANGEMENT OF DRAINS.

Necessity of System.--What Fall is Necessary.--American Examples.--Outlets.--Wells and Relief-Pipes.--Peep-holes.--How to secure Outlets.--Gate to Exclude Back-Water.--Gratings and Screens to keep out Frogs, Snakes, Moles, &c.--Mains, Submains, and Minors, how placed.--Capacity of Pipes.--Mains of Two Tiles.--Junction of Drains.--Effect of Curves and Angles on Currents.--Branch Pipes.--Draining into Wells or Swallow Holes.--Letter from Mr. Denton.