890 EXPERIMENT STATION EECOKD. 



of maintenance is attained oy preventing damage rather than repairing 

 damage." 



Some maintenance costs, P. Macy {Cornell Civ. Engin., 23 {1915), No, 8, pp. 

 506-512). — This article gives maintenance cost data for several types of roads 

 in New York, 



Treated wood-block paving, W. G. Mitchell {Dept. Int. Canada, Forestry 

 Branch Btil. 49 {1915), pp. 40, pis. 2, figs. 18). — ^This is a compilation of the 

 information at present available from researches made in different countries 

 in regard to the use of wood for paving. A bibliography is appended. 



Concrete hig-hways, G. W. Mtees {Cornell Civ. Engin., 23 {1915), No. 8, pp. 

 486-492). — The author presents certain observations based upon recently 

 acquired personal experience in the construction of concrete roads. A table 

 giving comparative cost data on the construction and maintenance of concrete 

 and macadam roads shows the concrete to be considerably the cheaper. 



Economy of small farm gas engines, D. P. Davies {Trans. Amer. Soc. Agr. 

 Engin., 8 {1914), pp. 73-80, figs. 7). — Experiments with three farm internal 

 combustion engines, fated at 1^, 6, and 10 horsepower, with reference to fuel 

 consumption at varying loads, are reported. All three engines were horizontal 

 hopper-cooled, the two larger sizes being identical in design, while the smaller 

 differed in form of combustion chamber and location and type of ignition. 



It was found that all the engines developed the best fuel economy not at 

 maximum load, but at a load approximately 67 per cent of the maximum. 

 All the engines carried the maximum load without signs of distress. The 

 point of greatest fuel economy coincided with the load where the governor cut 

 out every other explosion stroke. " It is possible that this condition has a 

 scavenging effect on every explosion stroke taking place, resulting in a higher 

 mean effective pressure for a given amount of fuel." 



Internal-combustion engine dimensions, H. L. Watson {Power, 41 (1915), 

 No. 20, pp. 672-674, fig. !)• — A chart for graphically determining the speed, 

 bore, and stroke for a given type and size of internal-combustion engine accord- 

 ing to American practice is given. 



Electricity as a factor in progressive agriculture, E. P. Edwaeds {Trans. 

 N. T. Elect. Soc, No 14 {1912), pp. 24, figs. 51).— The object of this paper Is 

 " to point out the possible, as well as the probable, advantages that will accrue 

 to the farmer and the country at large through the comprehensive use of 

 electricity by the agrlcultixral community." 



Tabular data are given of tests on electrically operated farm machines, 

 showing, among other things, the operating cost, including interest, deprecia- 

 tion, and labor, with the cost of electricity at from 1 to 10 cents per kilowatt- 

 hour. 



Draft of wagons, E. B. McCormick {Trans. Amer. Soc. Agr. Engin., 8 

 {1914), pp. 84-110, figs. 28; Engin. Rec., 71 {1915), No. 9, pp. 265, 266).— In this 

 article the traction dynamometer designed by the author for the Office of Public 

 Roads of this Department is described and illustrated, and results and conclu- 

 sions drawn from data obtained fi'om its experimental use are reported. 



A brief description of the instrument and its operation is as follows: The 

 Instrument Is attached to a standard city dray equipped with eight sets of 

 wheels having tires varying from If to 6 in. in width. The frame of the instru- 

 ment is suspended rigidly from the bed of the wagon. Two coil springs, through 

 which the power is transmitted, are in the line of draft from the tongue. The 

 tongue slides freely in its guides and is attached to the traction rod of the 

 dynamometer. As this traction rod is moved forward by the pull on the tongue, 

 the springs are compressed an amount corresponding to the draft exerted. TMs 



