Louis H. Gibson, Convenient Houses, With Fifty Plans for the Housekeeper
“ The soil pipe is of cast-iron, and usually four inches in diameter on the inside. It connects, full size, with the water-closet. Most other wastes are of lead, and are usually an inch and a half in diameter. In the soil and waste pipes there will naturally be the odors from the vaults and sewer, or from the foul matter which is in or passing through the pipes. Therefore, there must be means in each waste pipe, which connects a fixture with the main soil pipe, of preventing the passage of gas or air from it into the house. This is done by means of what is called a trap. ”
