BEFORE taking up my subject where we left off at our last lecture we will look at a picture illustrating two systems of plumbing as radically different from each other as any two things can be (Figs. 32 and 33.) The first, Fig. 32, represents the waste system of a small apartment house of three flats and gives, in addition, to two separate stacks of soil pipes, also a set of "back-vent" pipes as generally recommended by many plumbers today. There is also a separate rain-water stack, a main house trap with its special ventilating stack, similarly approved. Besides these many advise a special stack for local vent, as well as a drip pipe from the principal fixtures. Finally in some localities an exterior sewer vent pipe is called for by the sewer department. All of these except the sewer vent I have introduced in the same figure in order to present what many would consider an absolutely perfect outfit. It is copied from a drawing presented as a "model" by one of the leading plumbers in the country, except that I have added, as a finishing touch, the drip pipe frequently recommended for extra fine work. An exterior sewer vent to the roof should also be added where the disconnecting trap is used.

Fig. 30. Complexity with Inseurity.

Fig. 30. Complexity with Inseurity.

Fig. 31. Simplicity with Security.

Fig. 31. Simplicity with Security.

Fig. 32. Complicated plumbing, showing the modern tendency.

Fig. 32. Complicated plumbing, showing the modern tendency.

In Fig. 33 I have treated precisely the same fixtures in a somewhat simpler manner.

Now I have no doubt many of you have wondered why it was necessary to administer quite so powerful a dose of bacteria in a modest course on house plumbing. But if I show you presently that it is precisely the discoveries made upon these very marvelous organisms within the last two or three years which have justified our declaring the simpler of these systems to be by far the safer and better of the two, you will not, I am sure, regret the time we have spent upon them.

Fig. 33. Simpler and hotter plumbing which should he substituted for the complicated system.

Fig. 33. Simpler and hotter plumbing which should he substituted for the complicated system.

If it has been shown that the air of sewers does not swarm with disease germs, as has hitherto been supposed, and is freer from all forms of bacteria than the outer air above them, and that, in well ventilated sewers, this air is en- tirely innocuous, then, clearly, the disconnecting trap and its vent become useless, and should be omitted, so that the soil pipe may serve as an additional means of ventilating the sewers.

If, finally, it has been proven that, in connection with such a sewer, a sound and permanent water seal is a reliable barrier to the passage of odors and micro-organisms of any kind through the traps of fixtures, and that such a seal can now practically be obtained by a correct form of the seal alone, then, clearly, back venting becomes a back number, and the soil pipe can also be used as a rain water conductor, flushing itself.

I am perfectly aware that to sustain this very heretical position to your satisfaction, the proofs I bring forward must be unanswerable and very clearly presented.* The claim is a very vital and important one destroying, as it does, with a single sweep, a vast network of piping, which has been for a long time regarded as a necessity beyond all question. Therefore I shall make no excuse for treating the matter somewhat methodically and thoroughly, and shall endeavor to array the proofs in such order is will render them most easily intelligible. It is for this reason that we have in our first lecture investigated to some little extent the habits of some of the microscopic world of bacteria.

The next thing we must do is to become scientifically acquainted with sewer air; and in the next illustration I shall show you pictures of two kinds of sewer air, one the kind you find in well-constructed and thoroughly ventilated sewers, the other, however, residing chiefly in the imagination of the public and supposed to contain deadly poisons and all sorts of disease germs. The last is the kind plumbers seem to have in their minds when they erect in the houses of their wretchedly abused clients those formidable barricades of pipes shown in Fig. 2.

*This position was considered more heretical in 1899 - at the time these lectures were delivered, a time when trap venting: was almost universal, and even defended by a few engineers of some repute - than today, when cities and towns are rather rapidly abandoning the back-venting of traps, the use of the main or disconnecting trap and other old superstitions.

The first drawing, Fig. 34, illustrates a well built stone sewer of a modern city, and is very similar to one of the large sewers of Paris which I inspected in 1871. This sewer was so clean and well ventilated that it was not only much freer from germs than the street above it, but it was even without any offensive odor, so much so indeed that hundreds of people, both ladies and gentlemen visit them annually, as one of the particularly attractive sights of the metropolis. Compared with some of the filthy ones in our great cities, this sewer is a veritable health resort.

Fig. 34. Paris sewer.

Fig. 34. Paris sewer.

Fig. 35. Samples of disease germs supposed to exist in an unventilated sewer.