638 THE POPULAR SCIENCE MONTHLY. 



they drink. The same was shown in Egypt in 1883, in France 

 in 1884, and again in the department of Finistere almost at the 

 present time. 



In Italy, Naples has afforded one of the most striking examples 

 of the same thing. Commencing in August, 1884, the epidemic 

 spread by rapid strides until September llth, and then rapidly 

 fell. Between August 23d and November 9th some 12,345 cases 

 and 7,086 deaths occurred among a population of 492,908. At that 

 period the water supply of Naples was mainly derived from 

 trenches running from house to house underground, and was ex- 

 posed to direct contamination not only by soakage of filth, but 

 by the reckless practice of washing in the trenches linen soiled 

 by choleraic discharges. 



In the following year Naples was supplied with pure water 

 from a distant mountain stream (the Serino), and there followed 

 a marked immunity of the city from cholera, notwithstanding the 

 presence of the disease in the neighborhood. In 1887, however, 

 an injury to the Serino water conduit led to a temporary return 

 to the old system, and two sharp explosions of cholera at once en- 

 sued, but ceased on the resumption of the purer supply. Even 

 more demonstrative was the case of Genoa, a city provided by 

 means of three aqueducts with an excellent supply of a naturally 

 good water. After a few scattered cases a sudden and widespread 

 explosion of cholera occurred between September 21st and 24th, 

 the rich and the poor being indiscriminately attacked. It was 

 soon found that of the first three hundred cases ninety-three per 

 cent were in houses supplied by one of those aqueducts (the Nico- 

 lay), and on following that watercourse to its commencement 

 near the village of Busalla, thirteen miles distant, a colony of 

 workmen was found encamped. Cholera had broken out in 

 Busalla on September 14th, and inquiry disclosed the fact that 

 the clothing of the workmen, both of the sick and the healthy, 

 was washed in the river Scrivia, which feeds the Nicolay aque- 

 duct. The supply of this water to Genoa was promptly stopped 

 on September 28th, and the epidemic at once rapidly declined. 



Everywhere the same tale is told, but my present immediate 

 object is to insist that also in India, the " home of cholera," it is 

 now clear to me at least that water is the agent by which the 

 infection is carried from one human being to another. 



The experiences of Calcutta, as observed by Dr. W. J. Simpson, 

 the able health officer of that city, show that those persons who 

 have an abundant and pure water supply namely, the Europeans 

 and better-class natives escape cholera epidemics, except in iso- 

 lated instances which can generally be accounted for ; while the 

 natives who depend on tank water suffer severely when a tank 

 becomes polluted by the excreta of a cholera patient. 



