288 



EXPERIMENT STATION RECORD. 



[Vol. 37 



a \Tork for the gruidance of engineers in the practical design of hydroelectric 

 plants which would have the characteristics of accuracy, clearness, and com- 

 pleteness. Scientific discussions of various hypotheses and theories have been 

 ouaiitod except in case.=: where their incorporation in the text has been essential 

 to the understanding: of the subjects treated. ... A number of new and 

 original formulas appear, for the fir.st time, here. Among these may be men- 

 tior,e<l the exact formulas for solid dams and for the magnitude and location of 

 the resultants of forces acting on dams." 



Volume 1 contains tlie following chapters: General conditions, flow in streams, 

 woirs and orifices, power variation and storage^ artificial waterways, piije 

 lines and penstocks, dams, movable crests for dams, headworks. water wheels, 

 siieoil regulation of water wheels and abnormal penstock pressures, and a set of 

 matlieiiiatical tables. Volume 2 contains the following chapters: Alternating 

 current generators, transformers, switchboards, cranes, design and testing of 

 power stations, fires and cables, insulators, pole and tower line.s, electric cir- 

 cuits, calculation of transmission lines, deflection and meclianical stresses in 

 traiismi.ssion lines, line protection and acce.ssories. and substations. 



Methods and cost of screening and washing gravel for country road con- 

 struction, A. A. McKay (Eti'jin. and Contract., ^7 (1917), No. U. pp. 31S, 

 5/.'').— This is a description of methods of obtaining gravel of extra good qual- 

 ity from low-grade gravel in Calhoun County, Mich. 



Tests on comig'ated metal culverts [Tcchnol. Expt. Sta. [Univ. Me.] Bui. 

 i (1916), No. 1, pp. 15, flys. 2). — Te.sLs of the physical characteristics, crushing 

 strengtlis, amount of zinc coating, and acid tests of 13 galvanlze<l corrugated 

 metal pipes are reported, the results being summarized in the following table: 



Testa of corrugated metal pipes. 



'Reinforced at one end. 

 ' Fai e:l on aciouiit of rivets pulling out. 

 » Fai.ed soon l>€K^ause top was merely wired to bottom. 

 < Loading slightly ecceotric, hasteaing failure. 

 • Very scaly. 



Public road mileage and revenues in the Central, Mountain, and Pacific 

 States. 1914 (U. S. Dept. Agr. Bui. S89 (1917), pp. 56+LXXV, fig. 1).— Thia 

 report, prepared jointly by the Division of Road Economics of the Ofl^ice of 

 Public Koads and Rural Engineering and State collaborators. Is a compilation 

 showing mileage of Improved and unimproved roads, sources and amounts of 

 road revenues, and bonds issued and outstanding in tlie States of Arizona, 



