‘Indeed!’ ejaculated the orator, sharply. ‘If that be true,’ he whispered to me, in a rueful tone, ‘I shall be cut out of one of the best points in my speech.’ ‘Of course,’ continued the Engineer, ‘purity entirely depends upon the source, and the means of cleansing.’ ‘Then, as to the source—how many companies take their supplies from the Thames, near to, and after it has received the contents of, the common sewers?’ ‘No water is taken from the Thames below Chelsea, except that of the Lambeth Company, which is supplied from between Waterloo and Hungerford Bridges; an objectionable source, which they have obtained an act to change to Thames Ditton. The Chelsea Waterworks have a most efficient system of filtration; as also have the Southwark and Vauxhall Company; both draw their water from between the Red House, Battersea, and Chelsea Hospital. The other companies do not filter. The West Middlesex sucks up some of Father Thames as he passes Barnes Terrace. Except the lowest of these sources, Thames water is nearly as pure as that of other rivers.’ ‘Perhaps it is,’ was the answer; ‘but the unwholesomeness arises from contaminations received during its course; we don’t object to the “Thames,” but to its “tributaries,” such as the black contents of common sewers, and the refuse of gut, glue, soap, and other nauseous manufactures; to say nothing of animal and vegetable offal, of which the river is the sole receptacle. Brande shows that, while the solid matter contained in the river at Teddington is 17·4, that which the water has contracted when it flows past Westminster is 24·4, and the City of London, 28·0.’ ‘But,’ said the Engineer, ‘these adulterations are only mechanically suspended in the fluid, and are, as you shall see presently, totally separated from it by our mode of filtration.’ ‘Which brings us to your second point, as to efficient cleansing; you admit that without filtration this is impossible, and also that only three companies filter; the deduction, therefore, is that two-thirds of the water supplied to Londoners is insufficiently cleansed. This indeed, is not a mere inference; we know it for a fact, we see it in our ewers, we taste it out of our caraffes.’ ‘But this does not wholly arise from the inefficient filtration of the six companies,’ returned an officer of this Company, ‘the public is much to blame—though, when agitating against an abuse, it never thinks of blaming itself. Half the dirt, dust, and animalculæ found at table are introduced after the water has been delivered to the houses. Impurity of all sorts finds its way into out-door cisterns, even when covered, and few of them, open or closed, are often enough cleansed. In some neighbourhoods water-butts are always uncovered, and hardly ever cleaned out. The water is foul, and the companies are blamed.’