Sir William Henry Power. 



Ill 



dissemination of diphtheria from the consumption of milk. His report to 

 the Local Government Board on an " Epidemic Prevalence of Diphtheria in 

 ITorth London," dated December, 1878, contains a lucid account of the line 

 of reasoning which led him to the conclusion that milk was capable of acting 

 as a medium for the conveyance of diphtheria infection to the human subject. 

 Although the source of infection of the milk itself was not traced, demon- 

 stration in detail was afforded that the disease had been conveyed along 

 with milk distributed by a particular dealer serving the affected area. 



In 1882 Power, as the result of inquiry into an outbreak of scarlet fever in 

 St. Giles and St. Pancras, demonstrated a similar relationship between the 

 consumption of infected milk and the spread of scarlet fever ; suggesting, 

 moreover, the possibility that milk-borne scarlet fever might be due to a 

 disease of similar character in the cow rather than to contamination of the 

 milk from a human source. 



His investigation of a sudden and extensive outbreak of this disease which 

 occurred in Marylebone and certain other districts in December, 1885, 

 carried the matter a stage further by the interesting and important discovery 

 that cows suffering from a vesicular disease of the teats and udder constituted 

 the actual source of infection. 



Towards the end of the nineteenth century it became apparent that the 

 water supplied for drinking purposes in various areas, in Yorkshire par- 

 ticularly, was respou.sible for the caixsation of more or less extensive outbreaks 

 of lead-poisoning. The occurrence of a number of deaths among affected 

 individuals naturally directed attention to the special circumstances, and it 

 shortly became obvious that, in every instance, it was specially soft water 

 of acid reaction, derived from moorland gathering grounds, and delivered 

 under high pressure, that alone was capable of dissolving lead, sometimes in 

 considerable amount, from the local service pipes. 



So soon as information resulting from preliminary investigation of certain 

 of these outbreaks became available. Power, who evinced much interest in 

 the matter, at once realised that factors, in all probability hitherto over- 

 looked, or non-existent, must have come into play. To him it is that we 

 owe the original suggestion that the acidity to which it appeared that the 

 plumbo-solvent action of soft moorland waters was due, was in turn dependent 

 on the presence in the water of low forms of organic life. He further 

 suggested that these might find their necessary pabulum in the peaty material 

 abundantly produced on the gathering grounds from which such waters are 

 derived. And it was at his instigation that to Dr. Houston, now Director of 

 Water Examinations to the Metropolitan Water Board, was entrusted an 

 experimental inquiry on the subject of acid-producing bacteria in these 

 moorland waters, and, further, of the plumbo-solvent action of the acid 

 produced by the bacteria in culture media. As an outcome of this and other 

 investigations on the subject, of which one at least owed much to Power's 

 valued suggestions and kindly criticism, simple methods have been devised 

 for neutralising the action of any acids present in the water, with the result 



