It is easy to see how the popular idea of incompatibility has arisen in a case like that above stated of the Camp Farm tenant, eating up year by year all the fertility stored up in the land during the previous period, and letting nearly all the sewage run to waste, because its scientific application would cost much in thought and labour. In much the same way district councils have been, all over the country, stinting their labour bills and interfering with their managers’ purchases and sales in order to make as small a demand on the rates as they can—each year bringing some change of system—to the end that nobody is responsible or has any confidence in master or man. With such a state of things up and down the country the way was prepared for preachers of microbe agency to say, why should you buy all that land when a septic tank, a few acres of coke or burnt ballast, and a patent automatic opener and shutter of valves (which you see working so nicely with tap water and model at some exhibition) will give you “no more troublesome sludge,” and a first class effluent with hardly any labour bill? if you only agitate against that arbitrary Local Government Board, which insists upon land! But those gentlemen neglected the fact, that in a few years’ time their filters would have to be pulled to pieces, washed and put back, while the land remains as efficient as ever, and a valuable asset, in some cases saleable at building value, if it becomes desirable to move the outfall further at some future time. [Sidenote: Sludge treatment.] In the above comparison between natural and artificial treatment reference has been had chiefly to the aerobic branch of the business, but the anaerobic, breaking down _some_ of the solid organic matter and the sanitary disposal of the remainder in the state of sewage sludge (containing fully 90 per cent. of moisture) must not be overlooked or shirked as beneath the attention of the scientific bacteriologists and chemists whose analyses of effluents, and often of what they call crude sewage, are made from the liquid which has passed through a filter paper in their laboratory before their “oxygen absorbed” or “ammonia processes” are proceeded with. On the contrary, I have always maintained that sludge, being the foulest part of town sewage, ought to receive primary and earnest attention if we desire to improve the condition of our watercourses. When town sewage is pumped through a long rising main, it can often be spread on the land in its really crude state, and if the soil is clay ploughed up to receive it the sludge is most beneficial to its texture. But in every other case we must face the nuisance of extracting the sludge, and its desiccation in one of the following ways.