It therefore appears that if leaden pipes, and especially if leaden cisterns, are to be employed in the distribution and storage of water, on the system of interrupted supply, it will be a necessary safeguard, that the water thus conveyed and stored should not be of less hardness than from six to seven degrees, compared with distilled water as unity; and conversely, it also follows, that if the inhabitants of the metropolis are to gain the advantage of using a still purer and softer water, it will be requisite to do away with the existing leaden pipes and cisterns, and to substitute for them some material which shall not communicate any poisonous or noxious ingredient to the water. As matters now stand, we escape daily poisoning by the use of water loaded with earthy salts, and are thus compelled to drink an impure water on account of the impurity of our vessels. Would it not be better, and is it impossible, to drink the pure element from a pure cup? I remain, dear sir, with much respect, Yours obediently, THOMAS TAYLOR. To JOHN SIMON, Esq., F.R.S., Officer of Health to the City of London. THIRD ANNUAL REPORT. _November 25th, 1851._ GENTLEMEN, I have the honour of laying before you, in the various subjoined tables, such information as will enable you to measure the present sanitary condition of the City of London. * * * * * 1. The first table (Appendix, No. I.) contains a statement of the present population of the City, as derived from the Registrar-General’s recent census; and it compares the existing numbers in each division of the City with those given at the last enumeration in 1841. In examining this table you will observe that, during these ten years, the general population of the City has increased about 3⅖ _per cent._; that this increase has not been uniform through the nine sub-districts of your jurisdiction; that in some it has been unimportant; that in others there has been an actual decrease, extending even to 4⅔ _per cent._ on the previous population; while in the whole East London Union the numbers have risen considerably above the aggregate rate of increase, and in the St. Botolph sub-district exceed those of the former census by more than 16 _per cent._ Passing over the minor differences which have taken place in the distribution of the population, I cannot regard that larger increase without apprehension and regret. Probably for the most part it represents the continued influx of a poor population into localities undesirable for residence, and implies that habitations--previously unwholesome by their over-crowdedness--are now still more densely thronged by a squalid and sickly population. I congratulate your Hon. Court on the recent acquisition of powers (to the nature of which I shall presently advert) for the reduction and prevention of this serious evil. * * * * *