890 EXPEEIMENT STATION EECOED. 



Electricity versus steam in drainage pumping (Elect. World, 6^ {1914), 

 No. 6, pp. 275-277, figs. J/). — Data on first cost and operating expenses of steam 

 and electrically driven pumping stations used for draining agricultural lands 

 along tlie Illinois and Mississippi rivers are given. They show that the cost of 

 building a modern electrical pumping station varies from 50 to 60 per cent of 

 the cost of building a steam station to do the same work. It is claimed to have 

 been established that the total operating expense for electrical pumping stations 

 for drainage district service is from 10 to 35 per cent less than the total operat- 

 ing expense of steam stations under the same conditions. 



Construction and maintenance of sand-clay roads in Georgia — methods and 

 cost, J. C. Koch {Engin. and Contract., 42 {1014), No. 5, pp. 107-111. figs. 7).— 

 This article gives detailed methods and costs of both construction and mainte- 

 nance of sand-clay roads in Georgia, using top soil, other natural sand clays, 

 and artificially mixed sand clay for surfacing. 



Standard cross sections for Illinois roads {Engin. and Contract., 1^2 {1914), 

 No. 5, pp. 111-113, figs. 4)- — Cross sections for macadam, brick, and concrete 

 roads used in the construction of roads in Illinois in 1914 are given, with the 

 reasons for their adoption. 



The organization and standards of the Iowa Highway Commission {Engin. 

 and Contract., 42 {1914), No. 3, pp. 55-58, figs. 14). — This article describes the 

 organization of the Iowa Highway Commission and gives illustrations of the 

 road and culvert standards adopted by them. 



Standard I-beam and pile highway bridges of the Iowa State Highway 

 Commission {Engin. and Contract., 4^ {1914), No. 5, pp. 102-104, fiffS- 3).— 

 This article gives design drawings and essential data for standard I-beam and 

 pile highway bridges of this commission, as well as drawings of standard pile 

 abutments for steel highway bridges. 



Experiments on the effect of compression on a small gas engine, E. G. 

 EoEHM and W. W. Tangemann {Gas Engine, 16 {1914), No. 7, pp. 413-420, 

 figs. 10). — ^A series of tests on a vertical single-cylinder 4-cycle gas engine of 

 4f-in. bore and Sg-in. stroke, rated at 3 horsepower, hit and miss governed and 

 with mechanically operated valves, is reported. The object was to determine 

 and explain the effect of increasing the compression on the economy. 



The degree of compression was varied by changing the clearance volume, 

 which was effected by redesigning the cylinder head and providing for its ver- 

 tical adjustment by telescoping the head into the cylinder and placing spacer 

 rings under the shoulder, thus obtaining compression ratios ranging from 2.5 :1 

 up to 8.5 : 1. A large gain in economy as regards gas consumption and thermal 

 efficiency was obtained up to a compression ratio between 5 and 6 : 1. Above this 

 at all horsepowers the economy tended to decrease. The percentage of total heat 

 in gas absorbed by the jacket water reached a maximum at a compression ratio 

 of 3.5 to 4.5 : 1, and a minimum between 5 and 6 : 1. The British thermal units 

 absorbed by the jacket water per brake horsepower hour were least between 

 compression ratios of 5 and 6 to 1, and tended to rise beyond 6 : 1. The British 

 thermal units per brake hor.sepower hour appearing as sensible heat in exhaust 

 decreased up to a compression ratio of 6 : 1 and then increased above 6.5 : 1. The 

 minimum was reached at lower compression ratios with the higher loads. The 

 maximum horsepower obtained with various compression ratios increased 

 steadily by use of higher compression. 



It is concluded that for a gas similar to a natural gas having a high heating 

 value (950 to 1,100 B. T. U. per cubic foot) the most economical operation is 

 obtained by using compression ratios between 5.5 and 0.5 : 1. 



Fuel consumption of gasoline engines {Wisconsin Sta. Bui. 240 {1914), P- 

 41).— A series of tests conducted by F. White with farm engines of from 3 to 6 



