1917 J RURAL ENGINEERINQ. 89 



In tests of the effects of change in moisture content " specimens were made 

 of 1:2:4 and 1:3:6 concrete of very wet and very dry consistency. Several 

 days after hardening they were immersed in water and extensometer readings 

 were made on them at frequent intervals. As long as they were wet they 

 remained expanded, witli a maximum expansion of 0.0001 in. per incli of 

 length. After six months they were removed from the water and allowed to 

 dry in the warm, dry air of the laboratory. They immediately began to con- 

 tract, reaching an ultimate contraction of 0.0008 in. per inch of length." 



Policy and program, of Government in road construction under the new 

 Federal Aid Law, L. W. Page (Good Roads, 51 {1911), No. 7, pp. 116-118).— 

 This is a brief discussion of important features of the law. 



Good roads and community life in Iowa, J. E. Beindley and J. S. Dodds 

 (Iowa Engin. Expt. Sta. Bui. 39 (1917), pp. SI, pis. S, figs. 4).— This bulletin 

 presents the results of a study of good roads and community life in five typical 

 counties of Iowa, together with a detailed statistical tabulation of what is 

 termed strictly rural traffic. The points in question were (1) the proper distri- 

 bution of taxes for the construction and maintenance of roads, including 

 culverts and bridges, (2) the cost of marketing agricultural products under 

 the varying conditions presented by a State like Iowa, and (3) the educational 

 and social, as contrasted with the purely economic, value of properly con- 

 structed and well maintained public highways. 



It is concluded that " the proper distribution of taxes for roads and bridges 

 in a given State is necessarily determined by topography, density and character 

 of traffic, nature of local and commonwealth government with particular refer- 

 ence to the revenue system of each, the density of population and the distribu- 

 tion of the same both from a rural and urban standpoint, the progress of rural 

 organization service, and numerous other considerations." 



A survey of the number of farm homes located on different road systems in 

 the several counties showed " that about four-fifths of all the farmhouses con- 

 sidered are located on secondary or township roads. This fact tends to show 

 why there is opposition to spending a relatively high percentage of the highway 

 budget on a small mileage of main-traveled roads. . . . The house miles even 

 of strictly rural traffic reveal the necessity of relatively greater expenditure on 

 the country road system. In Story, Marion, and Carroll Counties it appears 

 that 12, 15.2, and 15 per cent of the roads carry 27.6, 33.9, and 38.8 per cent, 

 respectively, of the rural traffic as already defined, which means that the 

 density of the traffic on township roads is much less than on the county 

 roads. . . . Approximately four-fifths of the Iowa farmers live on the township 

 road system, and also about one-third of the farmers are directly connected with 

 city roads and need not use the county road system for market hauling. To 

 the former transportation costs are determined largely by the condition of the 

 secondary roads, while to the latter no direct benefit would be obtained from 

 the hard surfacing of what are now classed as primary roads." 



Tests of western yellow pine car sills, joists, and small clear pieces, C. W. 

 ZiMMEBMAN (f7. S. Dept. Agr. Bui. 497 {1917), pp. 16, pis. 2, figs. 4).— Tests of 

 the mechanical properties of western yellow pine, with special reference to its 

 use as a structural material, are reported. The following conclusions are 

 drawn : 



"The strength values of structural timbers are influenced considerably by 

 the defects found in them. These values vary according to the grades in the 

 green material, but the increase in strength from air seasoning is not uniform 

 and does not vary with the grades. Seasoning greatly increases the strength 

 of the wood, the increase being greater and more uniform in small, clear sticks 



