4. The aerobic process. The one essential point in this final process, whether in land or “contact beds,” is sufficient aeration (excess as by blowing has no result commensurate with cost of its introduction), and it can be attained by intermittence of sewage and rest, or by continuous passage of sewage through a bed of coarse medium kept always just moist in all its atoms by a rain-like dropping on the surface so carefully adjusted as to moisten all parts and not to form a water-seal in any part of the bed. Intermittence is easily arranged on any scale of working, and continuous filtration, on the contrary, is difficult even for a few thousand gallons a day.
Anticipation of a coming reaction against “fads” and overpressure in sanitation.
Since the above was written our grand old philosopher Herbert Spencer has published a volume of
“Facts and Comments”[3] containing a chapter on “Sanitation in Theory and Practice,” which points to a coming reaction against the movement begun, some fifty years ago, by the late Sir Edwin Chadwick and followed up by many enthusiastic exploiters of the popular dread of “germs,” which he associated with bad smells.
Of course the professor’s practical acquaintance with Chadwick’s hobby is, as he says, very limited, and his argument, that because sewage and manure smells are harmless in the open air of the country, they should be equally innocuous in a town, falls to the ground when brought to the test of experience, and I trust that Mr. Spencer will forgive me for pointing out that sewer-gas, drawn into a dwelling room, in town or country, through scullery waste pipe or other connection with a sewer in which the air is of lower temperature than that of the dwelling room, is really prejudicial to health whether accompanied or not by disease germs.
And although, as one of the experts to whom Chadwick appealed and whose moderate testimony was cast aside because it did not come up to the standard desired by his enthusiasm, I fully endorse Mr. Spencer’s caution with regard to the mass of Blue Book evidence on sanitation, I venture to express my regret that the dear old man has had an unfortunate experience of sewage treatment, and my surprise that so deep a reasoner should have published his judgment in this chapter without having taken the pains to extend his acquaintance with sewage treatment in other places than the single instance of Burton-on-Trent.
In thus despising an unsavoury subject Mr. Spencer is not alone, and I am sorry to have to say that general
indifference is answerable for the waste of much public health and money, because it need not be surprising if those following a despised trade are sometimes ready to take advantage of the prejudice and ignorance of their employers.
In this sense I beg to quote Professor Spencer as follows in justification of the reflection with which I began the above essay:—
"New sanitary appliances are continually being devised, sanctioned by authority, and required by surveyors; and surveyors may have and certainly sometimes do have, personal interests in pushing the use of them; either as being shareholders in the companies they are manufactured by or as receiving percentages on the numbers sold through their recommendation.”