case, the whole of the phenomena of cholera, as an epidemic, could not be explained. I, therefore, sought anxiously, and waited patiently, for some confirmation of this part of the subject before I should make my views known. Two outbreaks of cholera occurred, however, about the end of July 1849, one in Horsleydown, and the other in the Wandsworth Road, which I investigated, and which afforded what I considered conclusive evidence on the subject. The water drank by the persons attacked in each of these outbreaks had received, amongst other impurities, what must have come from a patient previously ill of the disease. I was able also to point out that the cholera was prevailing most in those districts of the metropolis which received their supply of water from certain parts of the Thames which contained the sewage of the town, and, consequently, whatever proceeded from the cholera patients. Before the end of 1849 I was able to show that a very close connexion existed between the mortality from cholera and the nature of the water supply, not only in London, but throughout the country. This connexion was very evident in certain towns, as Exeter and Hull, where the supply of water had been changed between the epidemic of 1832 and that of 1849. Where a polluted supply was changed for an unpolluted one, the cholera was almost prevented; and where a scanty but unpolluted supply had been changed for one contaminated with the sewage of the town, the epidemic prevailed to a fearful extent. The attention of Dr. Wm. Budd and Dr. Farr was directed to this subject, with the result of confirming what I had stated. Between the epidemics of 1849 and that of 1853, one of the water companies supplying the south districts of London changed its source of supply from the middle of the town, near the foot of the Hungerford Suspension Bridge, to Thames Ditton, at a part of the river which is beyond the influence of the tide, and, therefore, out of reach of the sewage of the metropolis. In the autumn of 1853 it was shown by Dr. Farr[1] that the districts partly supplied by this, the Lambeth Water Company, with improved water, suffered less than the districts supplied entirely by the Southwark and Vauxhall Company with the water from the river at Battersea Fields, although in 1849 they had suffered rather more than the latter districts. By showing the water supply in subdistricts, and thus getting a more correct line of demarcation, I was able to point out[2] that the advantage in favour of the population partly supplied with the purer water was even greater than Dr. Farr had indicated.