| Population in 1851. | Deaths by Cholera | ||
|---|---|---|---|
| In 15 wks. ending October 21. | To every 10,000 living. | ||
| Chelsea, south | 19,050 | 122 | 64 |
| Chelsea, north-west | 17,669 | 99 | 56 |
| Chelsea, north-east | 19,819 | 71 | 36 |
| Belgrave | 40,034 | 238 | 59 |
| St. John, Westminster | 34,295 | 173 | 50 |
| St. Margaret, Westminster | 31,314 | 238 | 76 |
| Total of districts supplied by the Chelsea Water Company | 162,181 | 941 | 56 |
| Houses supplied by the Southwark and Vauxhall Company | 266,516 | 2,900 | 108 |
| London | 2,362,236 | 10,530 | 45 |
| London, except the houses supplied by the Chelsea Company, and by the Southwark & Vauxhall Compy. | 1,933,539 | 6,689 | 34 |
The quantity of impurity in the Thames was greatly increased during the late autumn, by the long course of dry weather. From 5th August to 12th September, a period of more than five weeks, only 0·29 of an inch of rain fell at Greenwich, as appears by the report of the Astronomer Royal. The stream of the Thames above the reach of the tide became so slender, that it was difficult to navigate barges above Richmond. The Thames in London is a very large body of water, and if the whole of it flowed away into the sea every day, the liquid which flows down the sewers in twelve hours would form but a very small part of it; but it must be remembered that the quantity of water which passes out to sea, with the ebb of every tide, is only equal to that which flows over Teddington Lock, and from a few small tributary streams. In hot dry weather this quantity is moreover greatly diminished by the evaporation taking place from the immense surface of water exposed between Richmond and Gravesend, so that the river becomes a kind of prolonged lake, the same water passing twice a day to and fro through London, and receiving the excrement of its two millions and more of inhabitants, which keeps accumulating till there is a fall of rain. In time of cholera, the evacuations of the patients keep accumulating in the river along with the other impurities; and it is probably in this way that the dry weather with a high barometer aids in promoting cholera, as it has often been observed to do.
IMPURITY OF THE THAMES.
I thought at first that the quantity of common salt, previously mentioned as being present in the water of the Southwark and Vauxhall Company, consisted entirely of the salt which had passed down the sewers into the river, for I had no idea that any admixture of sea water reached as high as Battersea Fields. Mr. Quick, the engineer of the above Company, informed me, however, that an impregnation of salt water does extend as far after a long course of dry weather. It is obvious that a dry season, whilst it increases the quantity of impurity in the Thames, must also cause the sea water to flow further inland than at other times. I did not examine the water of the Thames in August or September, but I have done so now, at the latter part of November, and I am inclined to think that even yet a slight admixture of sea water may reach to Battersea Fields with every tide. I found 5·8 grains of chloride of sodium per gallon in water obtained at Hungerford Market, at half-flow of the tide, on 19th November, and 19·1 grains per gallon, in water obtained at the same place, on 27th November, at an hour and a half before high water; whilst water obtained at London Bridge, on 28th November, at high water, contained 63·3 grains per gallon.
A specimen of water obtained on 21st November, from a house supplied by the Southwark and Vauxhall Company, contained 28·8 grains of common salt per gallon, or about three-quarters as much as it contained in September, when the quantity was 37·9 grains. It is very obvious from the above analyses, that the Water Company obtain their supply from the Thames at high water, or nearly so, although this is the time of the tide when the water contains the greatest amount of impurity. It is quite certain that the sea water cannot reach to Thames Ditton, any more than the contents of the London sewers, and therefore, whatever may be its source, the quantity of chloride of sodium in the water is quite conclusive as regards the purpose for which I examined into it, viz., to distinguish between the water of the two Companies.
When the water of the Southwark and Vauxhall Company was examined by Messrs. Graham, Miller, and Hofmann, at the latter part of January 1851, it contained only 1·99 grains of chloride of sodium, or about one-twentieth as much as it contained last September, and one-fifteenth as much as on 21st November 1854.[[19]]
ALLEGED EFFECT OF LEVEL.
Dr. Farr discovered a remarkable coincidence between the mortality from cholera in the different districts of London in 1849, and the elevation of the ground; the connection being of an inverse kind, the higher districts suffering least, and the lowest suffering most from this malady. Dr. Farr was inclined to think that the level of the soil had some direct influence over the prevalence of cholera, but the fact of the most elevated towns in this kingdom, as Wolverhampton, Dowlais, Merthyr Tydvil, and Newcastle-upon-Tyne, having suffered excessively from this disease on several occasions, is opposed to this view, as is also the circumstance of Bethlehem Hospital, the Queen’s Prison, Horsemonger Lane Gaol, and several other large buildings, which are supplied with water from deep wells on the premises, having nearly or altogether escaped cholera, though situated on a very low level, and surrounded by the disease. The fact of Brixton, at an elevation fifty-six feet above Trinity high-water mark, having suffered a mortality of 55 in 10,000, whilst many districts on the north of the Thames, at less than half the elevation, did not suffer one-third as much, also points to the same conclusion.
I expressed the opinion in 1849,[[20]] that the increased prevalence of cholera in the low-lying districts of London depended entirely on the greater contamination of the water in these districts, and the comparative immunity from this disease of the population receiving the improved water from Thames Ditton, during the epidemics of last year and the present, as shown in the previous pages, entirely confirms this view of the subject; for the great bulk of this population live in the lowest districts of the metropolis.
The prevalence of cholera has been very much under the influence of the water supply in other towns besides London. The cholera has prevailed to a considerable extent in the crowded habitations of the poor in Liverpool and some other towns, where the general supply of water was not in fault, but I know of no instance in which it has spread through all classes of the community, except where the general supply of water has been contaminated with the contents of the drains and sewers; and all the towns with which I am acquainted that have enjoyed an almost complete immunity from this disease, have a water supply quite free from any chance of contamination. Birmingham, Bath, Cheltenham, and Leicester have nearly escaped the cholera in every epidemic. The few cases that have occurred being chiefly those of persons newly arrived from places where the disease was prevailing, and a few others who came in communication with them. All these towns have a supply of water quite free from connection with the drains and sewers, and the small rivers which flow through them are so impure that it would be impossible to drink the water. Leicester is crowded with a poor population, and has hardly any physical advantage except its water supply.