The Purification of Sewage by Bacteria. 37 



nuisance therefrom. A doubt has often been expressed whether 

 the system would be as successful in dealing with sewage 

 strongly charged with manufacturing refuse as it is with an 

 ordinary domestic sewage ; but this has now been completely 

 demonstrated at Yeovil with a sewage which is pronounced by 

 competent judges to be one of the foulest in England. 



There is one function of sewage works which must not be 

 overlooked. The bacteria which bring about the decomposition 

 of sewage matter are the sworn foes of disease germs ; and it is 

 by their means that the ravages of disease are kept within 

 bounds. In the septic tank, and again in the filters, any disease 

 germ.s which the sewage contams are systematically exposed to 

 the attack of their deadly enemies, first of one kind, then of 

 another. The works thus furnish an efficient safeguard against 

 the propagation of disease by the sewage with which they are 

 dealing. 



Professor Redfekn, in proposing a vote of thanks to the 

 lecturer, said Mr. Martin's discourse had been so lucid and able 

 on the new method of sewage treatment, that everyone who 

 had thought anything on the matter should be deeply interested. 

 The world seemed to have come to a general conclusion that 

 bacteria did nothing but mischief, but Mr. Martin had shown 

 that they were the great scavengers of effete matter, and played 

 an important part in the economy of nature. Belfast had been 

 recently visited by a typhoid epidemic, but so had other towns 

 and cities, and that ought to be remembered when the present 

 outcry was raised. The lecturer had shown — and he (Professor 

 Redfern) was prepared to believe it— that these bacteria 

 destroyed the solid matter in sewage. Exeter had already 

 shown in this matter of sewage purification what could be done 

 on a small scale, and they all looked forward with great zest to 

 its showing them the way in what could be done on a large 

 scale in this very important matter. 



Mr. J. W. GiLLiLAND, C.E., seconded the vote of thanks. He 

 said that a sewage farm, which system seemed to find favour 

 with some, was quite impracticable for a large city like Belfast, 



