Q. Some time ago I had the soil-pipe of my house ventilated through the roof, capped with an ordinary cowl, and the old filthy pan-closet removed.

I put in place of it an improved form of hopper-closet of all-earthenware, and had the bath and bowl wastes enter soil-pipe below closet. It is now free from smell and works perfectly, except that during heavy winds I notice that the water in closet is violently agitated and almost emptied, so as to almost break the seal of trap.

Thinking the air from sewer or soil-pipe was being forced into the house, I sponged out enough water to almost unseal the trap, and was surprised to find a strong suction into soil-pipe from the apartment.

I should like to know the cause of it, and have sketched the position of my fixtures, which are all in the rear of house and discharge into a sewer in front street about 80 feet from vertical soil-pipe, with trap outside of house, as my plumber says, but without any inlet for fresh air.

If there is a trap in drain without an air-vent, I presume the wind blowing across the cowl produces a vacuum in soil-pipe, and consequently trap of the closet is partially syphoned out; but if there is no trap in the drain, how could the wind blowing into the sewer produce similar result when the soil-pipe is open on roof, 12 or 15 feet above closet, as I am told by one party must be the cause? Could a downward draught through soil-pipe and into sewer produce such action on water-closet, and if such was the case would it not prove that there was no trap in drain? My house is located on a hill, where the wind has full sweep in one direction, and the sewer is some 15 feet deep in street. There are perforated manholes on the sewer every few hundred feet.

A. The most simple way to account for the disturbance of the water in the closet-trap is by supposing the plumber's statement to be correct - viz., that there is a trap on the main drain with no fresh-air inlet, and that the wind blowing across the cowl on the top of the house creates a partial vacuum in the soil-pipe. This is probably the state of the case.