*"Vagaries of Sanitary Science."
The doctor has also a kind word for the plumber of that day, of whom he wrote: "This guide, philosopher and friend proceeded without delay to fabricate and set traps for us, which he said would shield us from the deadly vapor. He had no sooner put one in than it was shown that the gas was generated in such quantities in the sewer that it was forced past the trap. The next one he placed went through that inscrutable process of 'siphoning out,' and we were worse off than if we had no traps at all. We must now ventilate them; when this was done, the joints began to leak, and he said the materials of the pipes were so weak that it could not stand the peppermint test; and in some way that future improvisation alone would explain, it was proclaimed that sewer-gas escaping from a pin-hole would cause disease much more surely than if it were passing out in volumes a foot in diameter. There was no safety but tearing out all of the old fixtures and replacing them with new ones. After their renewal we were no better off, for not a day passed that the sanitary dervishes did not relate the poisoning of whole families by sewer-gas."
This makes entertaining reading, but we know now that the mistake the doctor made was in failing to distinguish between what was dangerous and what was not. His diatribes, however, were useful in instigating more careful study of the facts, though he was entirely justified in his strictures on the increasing complication of plumbing and on the back venting of traps.
These disputes among the sanitarians might have been avoided if they had defined the kind of sewer-air they were discussing. If one side had reference to the air of such sewers as the underground sanitariums of Paris, I have shown you, with their aquatic pleasure parties, and the other had in mind the mephitic gases of horribly foul cesspools, their discussions must necessarily be interminable.
The very discussions, however, gave rise to eager inquiries for statistics and closer observations on the part of scientists, so that now we have a long record of observed cases of injury to the health of persons exposed to sewer-gas of various kinds.
These statistics can be read by the layman as well as by the physician, and one of the best and most interesting reviews of them has been made by a civil engineer, Mr. Roechling.* Indeed the physicians and scientists lack often the time to master the applications of their own researches and discoveries to sanitary engineering and plumbing. Thus one of the most recent works on sanitation and hygiene written by a physician devotes a chapter to plumbing and sewerage which contains many errors in design and principle. His instruction, for instance, that every soil pipe branch serving two or more water closets should be extended up above the highest fixture in the house or above the roof, would please the pipe dealer, but tend to bankrupt the average owner, besides adding immeasurably to the complication and leakage possibilities, especially in large houses and hotels. His rule should have been worded "every stack of soil pipe should be extended up through the roof." To extend also every branch to the roof would add complication even the most rugged pipe dealer would hardly dare to advocate. In a cut introduced to illustrate good plumbing, many undesirable things are shown; some merely slight errors in drawing, as where a trap is shown without any seal, and other errors in principle, as where fixtures discharge into vent pipes, where branch pipes enter the soil pipe with T instead of Y joints, and where very small vent pipes are carried up great lengths above the highest fixture and through the roof, instead of joining the soil pipe just above the highest fixture whereby both unnecessary expense and complication, as well as danger from closure by frost and snow would have been partially avoided.
*"Sewer Gas and Its Influence Upon Health," by H Alfred Roechling, C. E. Biggs & Co., London, 1899.
Fig. 36. D Trap set on its side.
Fig. 37. Vented S Trap.
Another drawing shows a D trap, Fig. 36, placed in a manner quite novel in plumbing practice. But the most important inaccuracy is that, whereas in the D trap, accumulations of grease and dirt are shown in ample quantity in the unscoured parts, the vent opening of the S trap adjoining the D is shown entirely free from deposit.
Now this vent opening, being entirely outside of the waterway of the trap, must receive even less scour than the comparatively innocent corner of the D trap. By what miraculous intervention of Providence then, has this vent mouth cavity escaped contamination when the D trap corner has been packed solid full? What friendly influence, too, has protected the cavity at the right side of the D and neglected the left side? As a matter of fact the mouth of the vent pipe will clog even easier than the unscoured portions of the D or pot trap because as long as warm, fatty vapors rise in the vent pipe, they will deposit and congeal more or less grease along its cool sides at varying distances above the mouth, thus adding to the desposits caused by splashing and liquid contact. In short the mouth of the vent pipe forms an unscoured "pocket" quite as dangerous as any of those other pockets, now universally condemned, which constitute the one great characteristic defective feature of all "cesspool" traps.
If the D or any other form of cesspool trap actually clogs at times as the doctor rightly says it does, and the passageway through it gradually approximates the form of the S trap, as shown in Fig. 37, then evidently the vent pipe mouth at the top of the cesspool trap will be shut off by this same deposit, and whether the S trap be constructed of grease or of lead its vent mouth will be similarly closed.