1917] RURAL ENGINEERING. 489 



The sig:nificance of streptococci in water supplies, W. G. Savage and W. J. 

 Read (Jonr. Hyg. [Cambridge], 15 {.1916), No. 3, pp. S54-S5i ) .—Experiments 

 with deep-water supplies, including samples from springs and deep wells, and 

 with surface-water supplies, including samples from shallow wells, are reported. 

 The purpose was to determine the relation of the presence or absence of 

 streptococci to the quality of the water. 



It was found that the results of analyses studied in bulk and the results 

 of detailed consideration of individual supplies were essentially the same. 

 The absence of streptococci is considered of less significance than their pres- 

 ence, and even their absence from a considerable bulk of water is not accepted, 

 to the same extent as the absence of Bacillus coli, as reliable evidence of the 

 freedom from serious contamination of the water at the time of sampling. 

 Absence of streptococci is, however, considered a point in favor of the purity 

 of the water. 



" Standards for permissible number of streptococci broadly correspond 

 to similar numerical standards for B. coli, but are of less significance and 

 reliability." While it is thought that not enough is known about the varying 

 vitality and distribution of streptococci to say whether the presence of certain 

 strains may or may not be disregarded as evidence of excretal contamination, 

 it is concluded to be in general reliable to assume that streptococci in large 

 numbers are only present in waters from unsatisfactory sources. 



Results and conclusions from a year's operation of the activated sludge 

 sewage treatment plant of Milwaukee, T. C. Hatton (Engin. and Contract., Jf6 

 {1916), No. 19, pp. 407-409). — The results of experiments on securing activated 

 sludge, aeration, effect of low temperatures, sedimentation, and sludge dis- 

 posal are reported. With reference to sludge disposal it is concluded that there 

 is no difliculty in reducing the Milwaukee sludge to a marketable low-grade 

 fertilizer at less than its value. See also a previous report of experiments 

 (E. S. R., 35, p. 188). 



Public road mileage and revenues in the New England States, 1914 (U. 8. 

 Dept. Agr. Bui. 388 {1917), pp. 74)- — This is a compilation showing the mileage 

 of improved and unimproved roads, sources and amounts of road revenues, and 

 bonds issued and outstanding, and contains a description of the systems of road 

 administration, fiscal management, and other factors affecting road improve- 

 ment in each State. 



Report of the State Commissioner of Highways [of New York], E. Dui-tey 

 {Rpt. State Com. Highways, N. T., 1915, pp. 939, pis. 49). — This is a report of 

 the work and expenditures on highway construction, maintenance, and repair 

 in New York for 1915. 



Proposed motor-truck loads for highway bridges, O. W. Chixds {Engin. 

 Nexcs, 76 {1916), No. 19, pp. 898, 899, fig. l).—lt is stated that motor trucks are 

 the proper form of concentrated loads to spacify in the design or investigation 

 of rural highway bridges. "A typical truck is assumed to have two axles 

 spaced 10 ft. on centers, with the two wheels on each axle spaced 5 ft. on 

 centers. This truck covers a space 9 ft wide by 20 ft. long, symmetrical about 

 the truck center. One-third of the weight is on the front axle, two-thirds on 

 the rear axle. With this standard size and distribution the capacity may be 

 definitely and simply expressed as the total weight in tons of the loaded truck." 

 Diagrams giving maximum shears and moments covering the range from 5- to 

 24-ton trucks and spans up to 50 ft are given. 



The following table for 10-ton trucks may be used for any weight, as the 

 values vary in direct ratio with the weight 



