Microhic Life m Sewer Air. 211 



the air much longer than do the bacteria. Mr. Halclane con- 

 chided that it is to the presence of air from without that we owe 

 the more prolific existence of bacteria in sewers, and not vice 

 versa. His experiments led him to conclude that true sewer air 

 contained fewer micro-organisms than the air of a street, or even 

 the air of an ordinary living-room. Our experimenter did find, 

 however, that when the sewage was splashed about, there was a 

 large increase in the number of organisms observed, which is a 

 great argument against the formation of large sewers. It is 

 argued that tliere is much doubt as to the power of sewer air to 

 disseminate typhoid germs independent of water supply. My 

 own experience, arrived at by passing through three epidemics 

 of that disease in Croydon, fully convinced me that when sewers, 

 such as some of ours were in 1875, are loaded with typhoid 

 excreta, the germs which are capable of reproducing the disease, 

 do get conveyed fi-om sewers into human beings by aerial means, 

 either directly by air or through the water supply. In those 

 epidemics the very large number of domestic servants, especially 

 kitchenmaids and cooks, who became victims to tlie disease, was 

 one of their marked charactei'istics, the reason being that those 

 persons went downstairs into the basements in the early morning 

 before the house was thoroughly ventilated, and inhaled the 

 sewer air that had collected in the kitchen daring the night. 

 Then there was Dr. Buchanan's demonstration as to the reason 

 why fever existed on one side of two or three streets which he 

 specified, in which the water supply was the same, and the sewer 

 the same on both sides. In one set of cases, the air was admitted 

 into the houses from the sewer, in the other it was not. It is 

 clear, however, that ordinary sewer air cannot produce mischief 

 unless the organisms from particular forms of disease exist in 

 the sewer. It becomes the bounden duty of the authority to take 

 care that no such organisms continue to live and multiply there, 

 and that when cases of any infectious disease exist in a given 

 locality, they shall pay particular attention to the sewers in 

 that locality, and prevent them from discharging disease germs 

 into the streets from the open grids which are left for venti- 

 lating purposes. They will do this if they are only partially 

 ventilated, and are sewers of deposit. 



We are now in a position to answer the four questions which 

 I have put forward. First : Do microbes exist in sewer air ? 

 No doubt they may. If, however, sewers are properly laid, and 

 there is no sewage deposit, no impediment to discharge allowed 

 to take place, and no stagnant air in any part of it, there will be 

 no disease germs. 



Disease germs require time for development, and if excreta be 

 hurried away to their proper destination, where they may become 

 bonnes boudies for the carnivorous plants which should be found 



