possible to reckon back to the true population rate. I admitted 

 the fallacies to which the method was liable ; but, failing a proper 

 census, I do not know of any other method of checking the 

 results obtained by adding to the population of the previous year 

 the births and deducting tlie deaths. 



I was aware that the deep sewer system had not been ex- 

 tended to the whole area embracing Adelaide and suburbs, and 

 the discussion, as to the population and death rate, was purely of 

 a technical kind ; it was for the statistician, pure and simple, 

 and not for the practical sanitarian. When the inquiry came 

 actually to be as to the probable influence of the drainage system 

 on the public health, it was necessary to limit it as closely as 

 possible to the population within the drained area. I knew that 

 the whole of the City of Adelaide had been drained, but the de- 

 tailed returns of causes of death were not given for the city 

 separately, and if the inquiry was to be continued at all, I had 

 no choice but to take the returns for the registration district of 

 Adelaide. I had no means of knowing the area of that district ; 

 and though it was apparent that its population was greater than 

 that of the city, it was also certain that the city population 

 formed the large majority. It was a fair assumption that any 

 cause {e.g., drainage) which affected to an appreciable extent the 

 health of the large majority would make that effect to be seen in 

 the total. Clearly there were fresh possibilities of error intro- 

 duced ; but I could only use the figures at my disposal, and these 

 were for the Adelaide registration district. I would not have 

 been so much inclined to place confidence in the reduced mor- 

 tality from typhoid in that district in 1885-86, as tending to show 

 the beneficial influence of the drainage, but for the fact that there 

 had been no similar reduction in other districts of South Aus- 

 tralia, rather a slight increase, as shown in table of my paper. 

 Though the proportion of deaths from diarrhceal diseases had also 

 been reduced, I did not feel warranted in laying much stress on 

 that circumstance, as it was capable of explanation in another 

 way, viz., the smaller number of infants, who supply the chief 

 victims of these diseases. 



But it may h% said, if the subject was surrounded with such 

 difficulties, and if the conclusions arrived at had to be so carefully 

 guarded by saving clauses, why did I meddle it all ? In reply, I 

 can only plead that the subject was a very interesting and impor- 

 tant one. If further put on my defence, I would have to say 

 that in the first instance the question was not raised by me, the 

 claim being openly made that the mortality in Adelaide had been 

 reduced to about 14 per 1,000, as a result of the adoption of the 

 drainage system. But, after all, it must be admitted that I had 

 another object in view. Here, in Melbourne, we are in the 



