This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
Close attention should be paid to the connection between the closet and the soil pipe as this, except in the case of the hopper closet with metal trap, will come on the sewer side of the trap and must be made absolutely tight. Some of the best closets are constructed so that the connection shall be under water and any leak will at once betray itself. (A, Fig. 48.) Another patented connection retains about a pint of water in a ring where the connection is made, which will appear upon the floor if the connection is not perfect. The connection from this point to the soil pipe is usually made with a lead bend, which is caulked, by means of a brass ferrule, into the soil pipe.
All closets should be provided with a "local vent" outlet, a tube extending from the upper part of the basin to which a galvanized pipe may be attached and carried to the nearest warm flue for the ventilation of the basin, and all traps, especially where the discharge of higher fixtures may create a vacuum in the soil pipe, should be vented to the main stack of vent pipes.
Fig. 48. Wash-Down Closet.
Fig. 49. Syphon-Jet Closet.