[BY ALBERT M. WEBSTER, A. M. AM. SOC. C. E. (Published In 1892 AND 1893 )

The foundation stone on which the structure of Sanitary Science and Preventive Medicine rests is the germ theory of disease. The assumption is that a spec fic disease is produced by the presence of a specific germ in the blood, without which the disorder cannot occur. The diseases at present attributed to germ origin are known as zymotic diseases, and it is with these that sanitary science has to deal.

The assumption of the presence of the specific germ in the blood directs attention to the channels through which it may be introduced, and to methods of intercepting and destroying it before it enters the system. Food consumed and air breathed are the general conveyors of the zymotic germs, infection through wounds excepted. Complete sterilization of these conveyors would stamp out zymotic disease; but sanitary science, recognizing the practical impossibility of this effort, directs attention also to the source of the difficulty, the breeding grounds most favorable to the development of the germs; in other words, attempts the sterilization, removal, and destruction of organic filth.

Municipal sanitation directs its efforts to these fields in the aggregate, as effecting the community. House sanitation extends this work into the dwelling. Its canons are the immediate removal of all organic waste, and the insurance of pure air and food within the dwelling.

The removal of waste is largely effected through the drains by the water-carriage system. The necessary fouling of the drains makes it imperative that the air from them should find no entrance into the household, and it is one of the purposes of modern sanitary plumbing to insure the security of these drainage channels.

The accompanying illustrations of defects in plumbing in this particular have been taken from examples found in New York houses of the better class in fashionable parts of the city. In general they are houses in which the visible plumbing has been remodeled. In each case the defective drain was in direct air communication with the furnace, and when the furnace was in operation there was little reason to doubt that the air from the drains was drawn into the furnace and distributed through the hot-air flues to the house. The defects were discovered by the smoke test. A fan blower with furnace and appliance for producing pungent sulphurous smoke is attached to the soil pipe at the roof and set in operation. The smoke travels through the system of pipes and issues from defects or openings which may exist, either concealed or exposed.

In the case shown in Fig. 4, smoke was blown into the main soil pipe at the roof. It issued through the other pipes, extending to the roof, and also through the soil and other pipes at the roof of the adjoining house, and at the fresh air inlet of the adjoining house; arguing the connection of the drains of the two houses. The smoke also appeared at every hot-air register, in the house under test. The owner was confident that there was no connection between the furnace and drains in his house, as the plumbing had been very recently renewed at considerable expense. On opening the furnace air chamber it was found full of the smoke, which was seen to issue through defective joints in the masonry of the party wall, against which the furnace was built. The drains in the neighboring house were uncovered and found to be leaking and defective close to the party wall. Referring to Fig. 4, the course of the smoke had been through the pipe at the roof to the cellar and through to the adjoining house drain B into the furnace air chamber D by way of the defective joints in the party wall C, and from the furnace through the flues F to the rooms in the house G G.

Figure 1 illustrates a somewhat similar example, except that the drains which ran under the furnace were of earthenware and the joints defective, and there was no connection with the neighboring house. As in the first case, the smoke blown into the soil pipe at the roof issued from every register in the house.

Figure 2 illustrates a case similar to Fig. 1, except that the drain which ran under the furnace was an old brick drain with flagstone cover, the joints of which were open, and the drain itself was in foul condition.

Figure 3 is an example of the contamination of the air supply to the house, through an untrapped yard drain A opening close to the cold-air inlet B to the furnace F. When the furnace was in operation air was drawn into the air chamber, through the cold-air box B, and was distributed to the rooms of the house through the flues G. The untrapped yard drain A being so near to the furnace inlet, made it more than likely that air from the drains was at times drawn into the house.