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A.-The drains in this Colony are not ventilated.
350.-That is the chief trouble?
A.--I call that the great trouble, the primary cause of the smells.
351.--Do you think a covered drain, well ventilated would be better than an open
sewer?
A.—A covered drain properly ventilated would not be offensive.
352.--What you call a properly ventilated drain-every hundred yards or less?
A.-In steep streets like these you ought to have ventilators every fifty yards.
353.-Are you aware of any drains in the tropics being ventilated on the same system as the Local Government Boards?
A.—I have not had any experience in the tropics except in Hongkong.
354.-Do you
A. Yes.
think it likely the same rules would hold good in the tropics?
355.--But you think the ventilators ought to be every fifty yards?
A.—Yes, the more thickly populated the streets the closer the ventilators ought to be, supposing the gullies are well trapped, if not each gully becomes a ventilator in
a manner.
356. You know that shaft, do you think when the tide is up there is any ventila- tion to that shaft or will the air be sucked up into the houses?
A.-My opinion is that the rise and fall of the tide causes very little difference to the pressure of gas in the sewers, because it (i.e. the rise and fall of the tides) is gradual and if it rises gradually the gas is gradually forced out. You notice the smells on the upper levels are always stronger and more perceptible when the wind is from the North- East to North-West; the wind blows up the open ends of the sewers and forces the gas through the defective traps into the houses.
357.--Do you think these shafts will suck the air out of the houses through the main sewer and up the hill, or will the houses ventilate the main sewer themselves?
A.-Owing to sewer gas being much lighter than the ordinary atmosphere the pressure at the upper levels is much stronger, that is why the smell is stronger on the upper levels.
358.-In very few houses is there any trap? The question is would this sewer gas ascend to such houses or go up the hill?
A. Of course it will find its way into the houses. There are very few houses properly trapped, even the iron grates or traps you see, most of them I find lately-I may say I have not examined this as I ought to have done until lately and I find most of these traps are nothing more than a delusion and a snare. The midfeather that is supposed to drop into the water to form the trap in the cases I have come across just touches the water only, it is no trap at all. I have examined some traps full of water and by blowing with your mouth through the outlet at the back the air came out through the water in the trap.
359. And that is the ordinary trap used in Hongkong?
A. Yes, but I don't say all are in the same condition.
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