Change of Incidence of Small-Pox. 1 3 1 



return of an epidemic long delayed might commit more 

 terrible ravages in one year than the uniform endemic 

 disease in a long series of years. This appears to be just 

 the position to which we have arrived, and it is sufficiently 

 grave to demand that all the possible causes should be con- 

 sidered without prejudice or partiality. It is for this reason 

 that I have put forward the argument that, owing to the 

 imperfection of our sanitary and other arrangements, they 

 may carry a certain amount of danger past the age which 

 Bernoulli called the date of civil birth, when a person 

 becomes a useful member of society, and that as the in- 

 creasing death rate from small-pox at adult ages may be 

 the normal consequence of our sanitary position, it becomes 

 necessary to examine that position more closely, and to dis- 

 cover in what way it may be improved. One of the first 

 steps to be taken in the matter ought to be an exhaustive 

 analysis of the action of repeated vaccination now carried 

 out for some years on the death rate in the German empire ; 

 as on this point we have statistics of which one feels the 

 want in investigating the action of inoculation and the 

 earliest effects of vaccination. 



For instance, when it is claimed, as it was by Mr. 

 Baxendell, that vaccination does not now afford the pro- 

 tection which it did for many years after its general adoption, 

 the obvious answer is that adults were made immune by 

 previous epidemics, and that this acted alongside of vaccina- 

 tion ; whereas now, a vast section of the population have no 

 safeguard other than vaccination. But to weigh this argu- 

 ment we have onl}- the statement from the yearly Bills of 

 Mortality, delivered by Dr. Lettsom to a Committee of the 

 House of Commons in 1802, and its continuation in the 

 Report of the Medical Officer in 1881, which do not show 

 the incidence at different ages. I here wish to maintain 

 that the rise which has been noted in the death rate finds 

 sufficient reason to account for it in the reduction of the 



