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XXVIII] street, the Hamburg side, there were numerous cases of cholera; on the Altona side there were no cases. The houses on both sides of the street were of the same character and occupied by the same class of people. The only difference, so far as could be ascertained, was in the water supply: the houses on the healthy side of the street received Altona water; those on the cholera-stricken side, Hamburg water. It was remarked that a certain group of houses on the Hamburg side remained free from the disease. On investigation it was found that, unlike the other houses on the same side, these houses derived their water supply from an Altona main. As regards its relation to the water supply, this Hamburg epidemic is the exact counterpart of what happened in South London in 1854. Formerly this district was supplied with water by two companies— the Southwark and Vauxhall Company and the Lambeth Company. Both companies drew their water from the Thames— the latter from near Hungerford Bridge, the former from near Battersea Fields. The epidemic of cholera which visited London in 1849 was especially severe in South London. Subsequently the Lambeth Company removed its intake higher up the river to Thames Ditton, and consequently the water it supplied at the time of the 1854 epidemic had improved in quality. The Southwark and Vauxhall Company did not change their intake, and in 1854 they were still drawing their supply from the river near Battersea Fields. When cholera visited London in that year the death-rate from the disease in the houses supplied by the Southwark and Vauxhall Company amounted to 153 per 10,000 inhabitants, whereas that in houses supplied by the Lambeth Company was only 26 per 10,000. The mains of the two companies ran side by side, some houses receiving the water of one company, some that of the other. During the Hamburg epidemic it was also found that the incidence of cholera was three times greater among those who used the town water than among those who got their supplies from wells.

These and many similar facts which might be