METEOROLOGY WATER. 215 



Tlic nutbor reaches tbe couclusiini that '•contrary to i)revailliig opinion, 

 deforestation does not of itself always resnlt in drying np of streams and in- 

 crease in floods. The nsnal result is an increase both in the average flow and 

 in tlie tlood flow. In regions like southern Michigan tbe effect of deforestation 

 on stream flow is very likely to be less than the effect of subsequent drainage 

 and tillage." 



Water purification and similar processes, P. Askknasy (JuJirh. EJekti'O- 

 cheni., 12 {Hli).',). pt. 2, pp. (;7!)-(;s.], Ji(i. /). — Tbe literature of electrochemical 

 processes for this i)uri)ose i)ro])osed in 1005 is noted. 



Principles of sewage treatment, W. 1'. Dunbar, trans, by H. T. Calvert 

 (.London, 1908, pp. XXIII+271, figs, l.'/l). — This book attempts to group and 

 critically describe the various phases of development of sewage treatment. 



The section dealing with surface irrigation is of particular interest from the 

 agricultural standpoint. It deals with tbe methods used and their efiiciency, 

 and the utilization of sewage as manure. It discusses this method of sewage 

 disposal from the economic and sanitary standpoints, pointing out the fact that 

 economic and sanitary interests are necessarily more or less in conflict in that 

 methods of application that will give maximum crop production will not secure 

 satisfactory purification of the sewage. 



Sewage purification abroad, IT. W. Clark {.four. Assoc. Engin. Soc, J/l 

 {1908), Xo. J, pp. 231-272, pis. S, figs. 2; ahs. in Municipal Jour, and Engin., 26 

 (1909), Xo. 4, pp. 125-128, figs. 6). — Information obtained "by an inspection of 

 sewage purification works in England and (Germany during tbe summer of 1908 

 is summarized. Tbe information relates to sewage farming, contact filters, and 

 sprinkling filters, with notes on preliminary treatment. 



The author found sewage farming in successful use in many places in Eng- 

 land, particularly at Wolverhampton. " This city has a population of 102,000, 

 and an ordinary sewage flow of 3,000,000 gal. per day. This is first treated 

 with lime, and, after settling in tanks, is turned onto a farm of 600 acres, 

 of which 4.50 are used for this purpose. The sludge is pressed into cakes 

 and is burned or used for filling. This farm is underdrained with tile. Like 

 so many English cities, this one is sewered on the combined system and the 

 storm water is brought to tbe disposal i)lant, where it is turned into a reservoir 

 11 acres in area with 3-ft. embankments, in which it slowly filters away through 

 the gravelly bottom.. The efliuent from the works is equal to that of tbe best 

 Massachusetts sand filters. Up to the end of March, 1908, the works had cost 

 $750,000, or about $7.50 per head of population. The cost of operation for the 

 year previous, less tbe profit from the farm, was $26,000, and the interest and 

 sinking fund payment would add about $30,000 to this. The average rate of 

 filtration is aboiit 8,000 gal. per acre per day. This gives a cost, including 

 fixed expenses, of about $49 per millon gallons treated." 



The recent report of the Royal Commission on Sewage Disposal states as one 

 of its conclusions that where land can be bought for not over $.500 per acre land 

 treatment is probably, other things being equal, the cheapest method of sewage 

 purification. 



Tbe nonsuccess of many English sewage farms is attributed by the author to 

 the fact that the soils, while well suited to farming, are poorly adapted to sew- 

 age purification. 



High, nitrification of sewage effluents, W. D. Hcott-Monchief (Jour. Hog. 

 Hort. Soc. {London], S't (1909), Xo. 3, pp. /ir>2-J,68, fig. /).— This paper describes 

 a simple method of obtaining highly nitrified sewage effluents for use in horti- 

 culture. The arrangement used consists essentially of " a sereis of superim- 

 posed trays, each containing suitable filtering material, so that the liquid 

 could drip from one to the other, with an ample provision of air in the spaces 



