Q. Where a water-closet or other fixture is connected with soil-pipe also used as a leader, is there any way of securing the trap on the water-closet from syphoning when the leader is gorged with rain; or would it be preferable to disconnect it entirely? The water-closet is on an upper floor, say twenty-eight feet from the roof. The leader is 4-inch, and the water-closet trap has no separate ventilation.

A. A vent-pipe, not less than three inches in diameter, should be taken from the highest point of the trap to above the roof. In this case it should not branch into this soil-pipe.