366 
Theodore Sedgwick Johnson 
CLARIFICATION EFFICIENCY 
As regards clarification efficiency, certainly the advantage will 
lie in the circular tank. While the advantage of the deep baffle 
may not be great, certainly the period of low velocity will be of 
value in securing efficient sedimentation. The uniform flow in 
radial lines will remove the necessity for ever reversing flow and 
will stabilize the flow in such manner as to permit the most 
normal conditions of settling. 
In consideration of the many probable items of difference and 
chance involved in Mther estimate, when applied to a single 
installation, it would be the writer's conclusion and thesis that 
the advantages of the circular radiahflow type of Imhoff tank 
over the type known as rectangular-linear flow must lie mainly 
upon its advantages as to clarification efficiency. And here too, 
enough questions will arise to make the problem one that can 
be best solved for each location or installation. 
Bibliography 
Sewage Treatment, Dunbar and Calvert, 1908, Historical Notes, ch. vii. 
Cleaning and Sewerage of Cities, pp. 134-142, 1905, A. Baumeister, translated by 
J. M. Goodell. 
Sewage and The Bacterial Purification of Sewage, 1906, Samuel Rideal, p. 267 et 
seq. 
Sewage Disposal, George W. Fuller, 1912, ch. xiii. 
Walls, Bins, Grain Elevators, M. S, Ketchum, 1911, Discussion of Stresses. 
Sedimentation, Allen Hazen, Transactions A.S.C.E., vol. liii, p. 45. 
Columbus Sewage Works, John H. Gregory, Transactions A.S.C.E., vol. Ixvii, 
p. 331. 
Separate Tank Compartments, Charles Saville, Journal of Assoc, of Eng. Soc., 
vol. xlvii, July, 1911. 
Sewage Disposal, Kinnicutt, Winslow and Pratt, 1910. 
Sewage Sludge, Eisner, Spillner and Allen, 1912. 
Sewer Design, H. N. Ogden, 1909. 
Sewer Construction, H. N. Odgen, 1908. 
Sewage Disposal Works, Hugh P. Raikes, 1908. 
Sewerage Systems, Hugh S, Watson, 1911. 
Sewage Treatment, Venable, 1908. 
Concrete Construction — Methods and Cost, Gillette and Hill, 1908. 
Handbook of Cost Data, H. P. Gillette, second edition, 1910. 
Principles of Reinforced Concrete Construction, Turneaure and Maurer, 1911. 
