188 



EXPEEIMEISTT STATIOIST BECORD. 



[Vol. 35 



found to contain from 4 to S bacteria per cubic centimeter. A repetition of 

 the process removed practically all the bacteria. Filtration is said to be 

 necessary as the process does not kill the bacteria. Canton tlannel is recom- 

 mended for filtration. 



The activated- sludg-e process of sewage purification, G. J. Fowler {Sur- 

 veyor, 49 {1916), No. 1255. pp. US-151).—Tlns is a summary of present knowl- 

 edge of both the scientific and practical phases of the activated-sludge process 

 of sewage purification, together with a list of 23 references to literature bearing 

 on the subject. 



Summary and latest results of experimental work on activated sludge at 

 Milwaukee, Wisconsin, T. C. Hatton {Engin. and Contract., 45 {1916), No. 5, 

 pp. 104-lOS}. — A summary of exi^eriments conducted since the beginning of 

 1914 is given, from which the conclusion Is drawn that " where a high and 

 uniform standard effluent is required no other known process equals it either in 

 first cost or cost of operation, and where the plant is of sufficient capacity to 

 -warrant the reduction of sludge to fertilizer the sludge problem becomes solved 

 as never before possible." 



Ninth annual report of the state highway commissioner to the Governor 

 of Virginia for the year ended September 30, 1915, G. P. Coleman {Ann. Rpt. 

 Highway Comr. Ya., 9 {1915), pp. W, pls. 26, fig. i).— This report deals, by 

 counties, with road construction, expenditures, etc., In Virginia during the 

 year ended September 30, 1915. 



Methods of brick pavement construction {Good Roads, 49 {1916), No. 6, pp. 

 55-61, figs. S). — Data obtained from inquiries addressed to a number of engi- 

 neers on the so-called monolithic type of brick pavement are reported. 



Forest Service proposes Douglas fir grading rule (Engin. Rec, 73 {1916), 

 No. 7. pp. 212, 213. fig. 1). — A rule proposed by the Forest Service of this 

 Department for grading Douglas fir timber for structural purposes is given. 

 This follows the recent trend of yellow pine rules in placing in the first 

 position clauses that determine the density of the timber. In addition to the 

 visual inspection for density — by a rings-per-inch clause — the weighing of dried 

 borings is provided for when the sticks do not meet the rings-per-inch rule. The 

 plan of restricting knots, shakes, and checks in beams is also followed. 



Gas tractors and their work, F. C. Perkins {Gas Engine, 18 {1916), Nos. 1, 

 pp. 1-9, figs. 15; 2, pp. 61-67, 105, figs. 9). — The details of construction, opera- 

 tion, and control of some of the well-known makes of gas tractors are described, 

 special attention being called to their advantages from the farmer's standpoint. 



General notes on power farming, E. R. Wiggins {Power Farming, 25 {1916), 

 No. 2, pp. 22, .^4). — This paper gives information on the care of cooling systems, 

 adjustment of farm gas engines, and use of the proper oil. Tests on four small 

 gas engines are also reported, the purpose of which was to learn what may 

 be expected of such engines of a given size and rating. The results are given In 

 the following table : 



Tests of small gas engines. 



