Fig. 94a. - Showing Stack of Soil-Piping as used for testing syphonage and Back-Pressure.

(2e.) With the Anti-D-trap fixed at B, instead of the Narrow-band D-trap, the result, in a similar trial, was just the same as in Test le, except that the water in this trap was left one-eighth of an inch lower. ,

(3e.) With a "full-sized" cast-lead D-trap fixed at b and the Narrow-band D-trap at c, a discharge from the closet-basin, A, as before, forced water out of the "Eclipse" trap at d, reducing its seal one-third: practically syphoned the seal out of the Narrow-band D-trap; and syphoned enough water out of the full-sized D-trap to leave it with only half the depth of its normal water-seal. But it is more than probable that this trap would have lost the whole of its seal had not the syphonic action upon it been broken by an accident. In one of the sides of the trap a piece of glass had been fixed for making observations, and upon the withdrawal of air from its interior by the motion of the pistonlike discharge through the soil-pipe, the trap collapsed, which at once broke the glass and allowed the air to rush in to fill the partial vacuum, and to break the syphonic action upon the water-seal of the trap.

8. The positions of the various traps were changed, and it was found by a series of similar trials to those already given, that while the full-sized D-trap withstood the action of syphonage better than any other closet trap - which would be what most plumbers would expect - the seal of the Anti-D-trap was less easily forced out by back-pressure than any of the other traps fixed at d. It took ten discharges to drive or force out the seal of the Anti-D-trap, fixed at D, by the back-pressure of air upon it from discharges sent through the main pipe, but some of the other traps had their seals forced out by only four discharges, the water playing up from them like a fountain, and partly falling back again into the trap, and partly falling outside, as shown in the illustration, fig. 94, A.

Another series of trials was made with the main soil-pipe open to the air full bore, at top and bottom, with the results as follows, viz.: -

(1/.) With the Anti-D-trap fixed at c, and the basin, a, filled with water and discharged ten times, the water was lowered about 3/4 in., leaving the trap at the end of the ten discharges with 1 in. seal.

(2/.) With a Narrow-band D-trap fixed in the same position, at c, and a similar number of tests, it lost a little over 3/8 in., leaving it with 7/8 in. seal.

9. Another series of experiments were made with the small bath, a, fig. 91, instead of the closet-basin, and this bath was placed over a 4 in. round-pipe trap fixed at b. The bath was discharged by means of a basin-plug fixed over its outlet, and instead of a pipe full bore at f, a 2 in. air-pipe was fixed.

(1g.) In two discharges from this bath, the Narrowband D-trap, fixed at c, lost three-fourths of its seal. During the whole of the time the discharge from the bath was passing through the main soil-pipe, the water in this trap was drawn away from its dip-pipe, and air passed through it to the soil-pipe very freely.

(2g.) The Anti-D-trap was then fixed instead of the Narrow-band D-trap, and subjected to the same test, and the result was that it was left with 1/8 in. less seal than the other trap,

(3g.) A 4 in. round-pipe trap was then fixed at c, and this trap was easily syphoned out by either a discharge-from the c oset-basin or bath.

10. The foregoing experiments prove that soil-pipes, like waste-pipes, must have their branches ventilated to prevent loss of water-seal in the traps fixed upon them. They also prove that when more than one trap is fixed upon a vertical stack of pipe, it is not sufficient to fix an air-pipe from the top of the trap and carry it back into the soil-pipe, as shown at e and f, fig. 95. A way of escape must be made for the air driven down by discharges through the main pipe from fixtures on a higher level, or the water-seals of the traps fixed under the fixtures at a lower level will be liable to loss, not only by syphonage, but also by back-pressure, as demonstrated by the foregoing tests.

11. To ventilate the branches or traps, as shown in fig. 95, is not ventilating the traps according to their needs, though, unfortunately, in practice they are often so treated. With such a method, during the time a discharge is passing through the main pipe, i.e., when the ventilation is most needed for the preservation of the seals of the traps, all ventilation is cut off from the traps below the place of the discharge; e.g., a discharge sent through the upper trap, A, fig. 95, would often pass through the main pipe - waste-pipe or soil-pipe - in a volume large enough to fill the bore of the pipe, in fact, like a water-plug, as shown at c, and which would for the time being leave the lower trap (or traps) without a vent, the evils of which we have just been considering.

Fig. 95. - Showing Bad Arrangement of Trap- Vents.

12. As my space is limited, I must refrain from further quotations on traps, except to show how certain traps can be made to maintain their seals; and for this purpose I cannot do better than give the results of some tests made upon a stack of soil-pipes still in use in my factory, and which I extract from "Dulce Domum."

Fig. 95a represents a stack of 3 in. lead soil-pipe which was fixed in 1881, with three closets upon it (g, f, and l) for the use of the people in my factory. The pipe was fixed of this small size as I was satisfied that it was large enough for its purpose, and that it would at the same time afford severer tests to be made upon the seals of the traps fixed upon it when experimenting. I ought just to say, in passing, that this 3 in. pipe has never once stopped up or given the smallest trouble, though the closets have been used by between thirty and fifty people daily for the last ten years. An anti-syphoning pipe is fixed, as shown by the thin lines, under the control of stop-cocks, for experimenting purposes - that is, from the lowest branch upon the stack a 2 in. lead pipe is fixed, and continued up and connected to the stack a little above the highest branch, with a 2 in. branch into it from certain branches on the stack for the proper ventilation of the traps. And the following results, out of many more which might be quoted of a like nature show clearly enough the value of fixing anti-syphoning pipes. In throwing large bodies of water down the stack through the upper closets, the greatest strain was brought to bear upon a trap fixed at M; and, as shown by the tests (3h.), an Anti-D-trap fixed at this crucial point, and when properly ventilated, stood a series of tests stronger than it is ever likely to sustain in practice, being left, after twelve discharges through the main pipe, with 1 1/2 in. seal.

Fig. 95a. - Showing a Stack of 3 in. Soil-Pipe, for Testing the Capabilities of a Small-Size Pipe, and for Experimenting with Traps, reduced from my work, "Dulce Domum.

(1h.) "With a pailful of water thrown down each of the 'hopper' class of closets, b f g, and with the valve-closet basin, d, filled to the brim and emptied sharply, and with the water from two small supply cisterns running into the two water-closets, p. and G, as well, making in all about 15 gallons discharged into the main pipe at one time - the 2 in. trap-ventilation, R v, being in use - a 2 in. ' Bower ' trap fixed at J, on the 2 in. branch, k, was syphoned; and a 9 in. ' Helmet' D-trap fixed on the 3 in. branch p, at n, had its water lowered 3/4 in.

(2h.) " With another discharge of water as last, without refilling the traps, the india-rubber ball of the ' Bower' trap floated away from the dip-pipe, and the water was lowered enough in the trap to pass smoke through it into the room from the main pipe. The ' Helmet' trap lost 1/8 in. more water by the second discharge, but it took ten further discharges to syphon this trap.

(3h.) "With the twelve foregoing discharges (15 gallons of water at a time) the ventilated ' Anti-D-trap' at M did not lose 1/4 in. depth of water, i.e., after the twelve discharges this trap had still 1 1/2 in. depth of seal.

(4h.) "With a 1 1/4 in. 'Bower' trap fixed at J, instead of a 2 in., a discharge of water through the main pipe as before completely syphoned it. After two such discharges smoke was sent through the trap into the room in volumes, by using an 'Asphyxiator,' and sending the smoke into the main pipe from the top, at A, above the roof.

(5h.) "With the 2 in. branch, k, lengthened, and the 'Bower' trap, either 1 1/4 in. or 2 in., standing 16 ft. away from the main pipe, there was little, if any, difference; for in similar trials to the last the trap lost its seal, both water-seal and 'mechanical' seal.

(6h.) "With a similar discharge as before, a 1 1/4 in.' Du Bois' trap, a 1 1/2 in. and 2 in. round-pipe trap fixed at J, on the branch, k, were each syphoned in succession. A 4 in. ditto lost 1 1/2 in. depth of seal in the first discharge, and after the second discharge the water stood 1/2 in. below the dip.

(7h.) "With a similar discharge, a 2 in. 'Eclipse ' trap, fixed in the same position as last, was syphoned in every trial. A 4 in. 'Eclipse' trap lost in the first discharge 1/2 in., second 3/8 in., and the third discharge syphoned it.

(fill.) "With a 1 1/4 in. ' Anti-D-trap ' fixed in the same position, and with a similar discharge of water, this trap was also syphoned. A larger size 'Anti-D-trap' held its seal much better.

(9h.) "With a small 'Narrow-band ' D-trap - 1 1/2 in. between the cheeks, and with 1 1/2 in. ' out-go ' - fixed on the branch, k, a similar discharge of water as before lowered the water 1 in., another discharge lowered it 1/8 in. more, the third discharge a little more, and the fourth discharge syphoned it. With a full-size ' Narrow-band ' D-trap it took forty discharges to syphon it. The first discharge took out 5/8 in., second 1/8 in., and seven succeeding discharges took each 1/16 in,

(lOh.) "With a full-size 'Helmet' D-trap, fixed as last, the first discharge lowered the water in it 3/4 in., second 1/8 in., third 1/8 in., and the five succeeding discharges took out by each discharge 1/16 in."