The ventilating pipe being carried above the roof is strictly in accordance with the bye-laws of the Local Board, although it spoils the appearance of the house. One reason why it was put there is to prevent the siphoning of the closet trap, and its height is to carry out the recommendations of medical writers in the _Lancet_ who have so often insisted that these tall pipes, carried some feet away from chimneys or bedroom windows, were necessary. Let us test this theory. We will flush the closet by throwing down slops and giving the closet the regular flush, carefully testing what takes place. The result is that the soil-pipe, instead of carrying off the odours from the top, only forms an air inlet, and 2¼ cubic feet of air has been sucked in at the top of the pipe, and the same quantity of gas discharged through the grating. As this grating on the plan is only 2 feet from the passage door which leads into the kitchen, the least that occurs is that a portion enters the house, and the cook has a slight headache when preparing the meals for the day. To be more certain of this let us test the working of the ventilation by a dozen flushings of the closets, and the same results are obtained by measurement, 27 cubic feet of air entered the top of the pipe, and has been driven out at the grating below. This proves that it is unnecessary to spoil the appearance of our houses by the erection of these pipes, or of carrying them above the soil-pipe or closet level. It would not be consistent for me here to state how these unsightly pipes could be avoided, but I am confident that ere long they will become obsolete, although they have been erected by thousands in various parts of the country. We will now test the working of the ventilation in drains A B, and those in branch drains to traps marked I. As they are clear, we find that the gases in them are not so poisonous as in the sewers to which they are connected. A manhole grating exists in the sewer some 40 yards from the back of the building, and through this grating the gas which is driven by the flushing escapes, and its density depends on the nature of the soil passing in the sewer. Its density is lessened by diffusion, or the mixing of the gas which takes place at the grating, but the time it takes for the gas which is in the drain near the traps I, to mix with the fresh air at the grating in the street is a problem that I will leave others to solve. We are certain that no gas in bulk can pass through the trap under ordinary circumstances. We can now certify that the drains are tight, well trapped and ventilated, they are laid strictly in accordance with the bye-laws of the Local Board, and we can quote that similar plans were exhibited last year at the Health Exhibition, as models for country architects and builders to copy; and ninety-nine out of every hundred sanitary inspectors would sign the certificate that the sanitary arrangements were carefully tested, and found perfect.