Under such circumstances street air passing through the sewers and house drains becomes filtered by them and emerges from the pipes freer from its dust and germs than when it entered, and must in fact before reaching the tops of the stacks above the roof be entirely freed therefrom.

(2) Air currents rising through the soil pipes in buildings act like smoke in chimney stacks, taking a spiral course as they ascend. In so doing, as well as in passing around bends and angles, every particle of air tends to strike against the inner surfaces of the pipes more or less often before reaching the roof. The result of this phenomenon is that any dust and germs which might enter the house drainage system from the public sewer is bound to be arrested somewhere along the wet surfaces of these pipes, and be ultimately destroyed. Hence with good plumbing the possibility of the entrance of a disease germ into the house from plumbing pipes becomes practically nil. If there is any danger whatever of contracting disease from air in the sewer itself so ventilated, all such danger is thus eliminated for residents in the houses connected therewith. More questionable germs are consumed every twenty-four hours in the ordinary food and drink or inhaled from the outer air than would probably be obtained from the soil pipe air in a lifetime.

(3) The omission of the disconnecting or main house trap converts every house drain into a sewer vent and insures the destruction of any dust and germs, pathogenic or otherwise, which may under normal or abnormal conditions be found in the sewer.

The rate of purification of the air of cities by this method of filtering it through the sewers and house drains is very great, amounting, by my calculation, to over a million and a half cubic feet per minute for every square mile of the city's area, or to the ventilation produced by a ventilating chimney 68 feet in diameter conducting air at a speed of 419 feet a minute.

(4) The use of the main house trap obstructs sewer ventilation, and results in forcing any foul and dangerous odors it may contain as well as any possible disease germs into the street through the sewer gratings.*

(5) The use of the "back vent" pipe with traps tends to destroy their water seal by evaporation, where unvented anti-siphon traps are capable of retaining their seals under all conditions encountered in plumbing practice, and for many months without refilling.

(6) Drain piping may now be installed in such a manner as to be permanently sound and reliable.

(7) Splashing and bubbling in sewers may be avoided by their proper construction and regulation.

(8) If there be any danger whatever from the possible presence in rare and isolated cases of disease germs in the air of the sewer, that danger may be practically eliminated by ventilating the sewer through the house drains and using sound piping and unvented anti-siphon traps. Under such conditions there is indeed a possible danger of contracting disease from dust and germs coming in through open windows, but none from the plumbing system, because the former may and the latter cannot transmit the germs.

*The money saving alone from omitting the main house trap and Its necessary connections and the extra piping it involves in a city of the say, of Boston, would amount to a sum sufficient to build and equip ten handsome public school houses, or in general, two for every square mile of a city's area.

In my suggestions for improvements and modifications founded on the above deductions hereafter to be described in detail in these pages, I have been guided by the following ten rules or principles:

(I) The Law of Simplicity. The tendency at present is toward undue complication. The plumbing work has been growing each year more elaborate and costly, more difficult to set correctly and more difficult to comprehend and repair when correctly set, so that the public have become alarmed and confused. They despair of being able to understand the intricate system of piping and machinery for the supply and waste fixtures. The result is a general feeling of insecurity and a tendency to forego plumbing fixtures wherever their presence is not an absolute necessity. Our watchword should be "simplicity." Rather than reduce the number of our conveniences, let us reduce the amount of machinery connected with them, provided we can do so without reducing the security they are intended to afford.

(2) The Law of Accessibility. Another leading principle is that all plumbing work in a house should be everywhere, without exception, accessible, and as far as possible visible and ornamental. Pipes should never run behind plaster when it is possible to expose them on walls and ceilings. There is nothing in a neatly arranged line of metal piping that one needs be ashamed of. On the contrary, when skillfully placed and neatly jointed, in a workmanlike manner, as would be the case when a good plumber knew they were to be forever exposed to view, these bright metal pipes, polished or white enameled, become quite ornamental when mounted with handsome clamps and symmetrically arranged with taste and judgment.

(3) The Law of Avoidance of Mechanical Obstructions. A third principle is to avoid all mechanical obstructions, such as balls, valves, gates and all other impediments to the waterway, and in a system of water carriage to do all trapping by means of a water seal alone.

Mechanical devices form no reliable security against the passage of sewer gas. These valves and balls cannot be made to fit their seats with such accuracy as to exclude liquids and gases, or microscopic germs, even when new. They soon become more or less fouled with dirt and corrosion and then their inefficiency becomes evident even to the eye. A sound water seal, however, properly protected, is found to be entirely reliable in excluding noxious matters of all kinds. Moreover, we are obliged to rely upon a simple water seal whether we desire to or not, because our water closet traps are and must be constructed without mechanical obstructions. It is useless to apply mechanical closures to our smaller traps if we leave the large water closet traps without them.

(4) The Law of Tightness and Flexibility of Jointing. A fourth principle is that all joints should be permanently tight, and to secure this evident desideratum no material should be used in jointing which is injuriously affected by any of the substances brought in contact with them, or by changes in temperature, concussion or shrinkage.

(5) The Law of Soundness of Material. A fifth principle is that all material used be sound, and all pipes of even thickness and capable of resisting a suitable pressure test.

(6) The Law of Thorough Ventilation. A sixth principle is that all main lines of soil and drain pipes should be thoroughly ventilated from end to end.

(7) The Law of Adequate Flushing. A seventh principle is that all parts of the waste receptacles and pipes be thoroughly flushed with water from end to end in such a manner as to remove all foul matter instantly from the house as soon as it is generated.

(8) The Law of Automatic Operation. An eighth principle is that the working of all parts of the plumbing system should be as far as possible automatic.

(9) The Law of Noiseless Operation. A ninth principle is that the operation of all parts of the work should be noiseless.

(10) The Law of Economy and Prevention of Water Waste. Finally, all parts of the work should be economical in construction and designed in such a manner as to avoid the chances of waste of water and damage of property through leakage.

These ten broad principles must be accepted by all sanitarians. I designate them as the ten laws or commandments of plumbing. They are self-evident, and may be at once adopted as axioms without discussion. It is to be regretted that in the manner of applying them in practice, however, we do not find the same universal harmony.

535 Beacon St., Boston. Jan. 1st, 1911

Introduction 7