It is notorious, for example, that at the present hour, the Thames is poisoning London.

So far as Paris is concerned, it has become indispensable of late, to transport the mouths of the sewers downstream, below the last bridge.

A double tubular apparatus, provided with valves and sluices, sucking up and driving back, a system of elementary drainage, simple as the lungs of a man, and which is already in full working order in many communities in England, would suffice to conduct the pure water of the fields into our cities, and to send back to the fields the rich water of the cities, and this easy exchange, the simplest in the world, would retain among us the five hundred millions now thrown away. People are thinking of other things.