CONTENTS. PAGE BAD DRAINS, AND HOW TO TEST THEM 1 SEWER VENTILATION 32 THE ORIGIN AND TRANSMISSION OF ZYMOTIC DISEASE 56 BAD DRAINS; AND HOW TO TEST THEM. “Bad Drains.” How often has this term been used during the last few years? By the medical profession alone, thousands of cases have been attributed to this cause. To the honour and credit of that profession its members have thought out and worked out the cause of innumerable cases of disease under their charge, and rightly fixed their origin to be due to “bad drains.” In many cases it has been but a fashionable term to describe cases which had the appearance of gas poisoning, but did not owe their origin to drains; but rather to the heated and impure atmosphere of rooms, late hours, and the sudden change from heat to cold. If there have been a few hundred cases where “bad drains” were supposed to have caused the illness and such was not the case, there have been thousands of others where the disease originated from them, but was taken as a matter of course, or as one of the frailties of the human frame, when undoubtedly the cause was “bad drains.” It is a most remarkable thing, that whilst on the one hand we have the medical profession energetically working to find out defects in the planning of drains and sanitary fittings, and writing articles on them, we have on the other hand surveyors and others who have treated the matter as a doctor’s fad. During the last five years scarcely a medical conference has been held without the question of “bad drains” forming one of the principal subjects discussed. Medical officers of health have made stirring speeches and reports to Local Boards; but where is the surveyor who has had the energy to do the same unless it has been actually forced upon him? It is a curious but noteworthy fact, that nearly the whole of the evils of badly constructed drains, and the principal improvements in them, have been forced on surveyors, builders, and plumbers by the medical profession and the public. The reticence shown by surveyors in dealing with “bad drains” may be attributed to their unwillingness to acknowledge the errors and defects in works already executed. These works were, at the time, executed according to the theories adopted by the most eminent engineers in the profession, and it would be considered unprofessional to admit errors. There is scarcely a district (excepting where drains have been laid within the last three years) where the branch drains are trapped into the main sewers with an efficient water-seal. Surveyors feel that to acknowledge this would be tantamount to acknowledging a want of professional knowledge or neglect of duty on their part.