In addition to this it must be understood that, owing to the great losses by evaporation and by growing plants, which are continually at work on sewage farms, especially during the summer months, when, as a rule, the flow of water in the brook that takes the effluent is smallest, the quantity of the effluent from the natural treatment is probably only from one-half to one-third that resulting from the artificial treatment, which is a point of very great importance.

If it can be proved to them that Nature is not sure and true enough in its methods, the Authors are prepared to assist it with methods and means produced by the inventive brain of man. But if such proof is not forthcoming, they adhere—in preference to groping in the dark—to Nature’s own methods, knowing from experience, that when allowed full scope and fair treatment, it is most sure in all its ways. That will not prevent them, however, from giving in the future, as they have done in the past, the question of sewage treatment in all its aspects their most careful consideration.

ALFRED S. JONES.
H. ALFRED ROECHLING.

London: September 15, 1902.

[1] ‘Sewage Treatment: Science with Practice.’ By Colonel A. S. Jones, V.C., C.E. Read at the International Engineering Congress at Glasgow, 1901. And ‘The Sewage Question during the Last Century.’ Read by H. Alfred Roechling, M. Inst. C.E., F.G.S., F.S.I., etc., on December 2, 1901, before the Society of Engineers, and awarded the Gold Medal of the Society.

CONTENTS.

Part I. By Lieut.-Colonel ALFRED S. JONES, V.C.

PAGE
Introductory[1]
The Chemist Dibdin discards Chemical Precipitation in favour of M. Pasteur’s Aerobic Organisms[3]
The Cleanly and the Dirty (Septic) Processes for Sludge Removal[5]
The Best possible Medium for Aerobic Organisms to Work in[5]
Tabular Statement derived from the Leeds Official Report of Experiments[7]
The Wrexham Sewage Farm[8]
The Camp Farm, Aldershot, to which Six other Areas of Sewage Works have been added from July 28, 1902[9]
Evidence and Reports of Lord Iddesleigh’s Royal Commission, 1898-1902[15]
Automatic Appliances for Sewage and Effluent Discharge[17]
Sludge Treatment[19]
Cropping a Sewage Farm[21]
Importance of having Tidy Contour Carriers Accurately Levelled[23]
Summary of the Experience of a Lifetime[23]
Anticipation of a Coming Reaction against Over-ridden “Fads” and too much Pressure in Sanitation[25]

Part II. By H. ALFRED ROECHLING.

I.Introductory Remarks[28]
II.The Sewage Question during the Last Century: a Short Retrospect[29]
III.The Subsoil:
1. Mechanical structure of soil[41]
2. Permeability of soil[42]
3. Water capacity of soil[42]
4. Water-retentive power of soil[43]
5. Capillary movements of water in soil[44]
6. Temperature of soil[45]
7. Subsoil air[47]
8. Movements of water in soil[47]
9. Micro-organic life in soil[50]
10. Absorbing powers of soil[51]
IV.Self-Purifying Powers of Soil. Natural Self-Purification of Sewage[52]
V.Artificial Self-Purification of Sewage:
1. General observations[68]
2. Artificial self-purification of sewage in intermittent contact beds:
 a. Name of process[70]
 b. Explanation of process [71]
 c. Water capacity of bed, and silting up[73]
 d. Absorbing powers of filling material[78]
 e. Consumption of oxygen by the filling material[79]
 f. Formation of carbonic acid[80]
 g. Nitrogen[80]
 h. Formation of nitric acid[80]
3. Artificial self-purification of sewage in septic tanks:
 a. Name of septic tank[81]
 b. Covered or open septic tank[81]
 c. Explanation of process[83]
 d. Velocity of flow through tank[85]
 e. Destruction and liquefaction of sludge in septic tanks[87]
 f. Formation of gas in septic tank[88]
 g. Mixing action of septic tank[89]
 h. Micro-organisms in effluent from septic tank[89]
4. Continuous contact beds[89]
VI.Management of Plants for the Artificial Self-Purification of Sewage[90]
VII.Some Observations on the Deposition of Suspended Matters in Tanks[91]
VIII.Concluding Remarks[93]
Postscript[95]

NATURAL AND ARTIFICIAL