684 EXPERIMENT STATION RECOED. 



institutions. A final section contains information summarized and tabulated 

 from the reports of county engineers. 



First annual report of the highway engineer for the period ended Novem- 

 ber 30, 1914, H. L. BowLBY (Ami. Rpt. Highway Engin. Oreg., 1 (lOl-i), pp. 

 2Jfl, pis. Jfi, figs. 54)- — Data, by counties, on road and bridge finances, design, 

 construction, and maintenance in Oregon for 1914 are reported, together with 

 miscellaneous tests of road materials. 



Road laws of "West Virginia, 1913, A. D. Williams (W. Ta. Dept. Agr. 

 [Bui. 1] (1013), pp. i03).— The text of the laws is given. 



Prison labor: Instructions, laws, and duties of officials, A. D. Williams 

 (TF. Va. Dept. Agr. Bvl. 4 {191J/), pp. 30, figs. 39). — Instructions, laws, and 

 duties of officials with reference to the employment of prison labor on road 

 work are outlined. 



The road drag, its construction and use, A. D. Williams (W. Vo. Dept. 

 Agr. Bui. 3 {191/f), pp. 29, figs. 26). — This describes and illustrates the con- 

 struction of .split log, steel, and plank road drags and gives brief instructions as 

 to their proper use. 



Earth and sand-clay roads, A. D. Williams (W. Va. Dept. Agr. Bui. 5 

 (1914), pp. 47, figs. 50). — This bulletin deals with methods and machinery for 

 the construction of earth and sand-clay roads. 



Relation between the properties of hardness and toughness of road-build- 

 ing rock, P. Hubbard and F. H. .Tacksox, Jr. (U. ^. Dept. Agr., Jour. Agr. 

 Research, 5 (1916), xYo. 19, pp. 903-907, fig. 1). — Hardness, toughness, and 

 binding power tests of about 3,()00 samples representing every known variety of 

 road-building rock are graphically reported bringing out the following points: 



" (1) The average toughness for all tests made is about 9. (2) The average 

 hardness increases with toughness, and the rate of increase becomes less as the 

 toughness values become larger. (3) Individual values of hardness vary 

 through wide limits for low values of toughness, and the variations from the 

 average decrease uniformly with the increase in toughness up to a certain point, 

 about 20, after wliich they remain constant with very little variation from the 

 average. (4) When any given value for toughness falls within certain limits, 

 which define the suitability -of tlie material for macadam-road construction 

 under different traffic conditions, the corresponding value for hardness will fall 

 within similar limits for hardness. . . . 



" If it be assumed that the curve represents a fair average of all available 

 types of road-building rock, it would seem that a determination of the tough- 

 ness of any particular sample of rock shows, for all practical purposes at least, 

 whether it is hard enough to be satisfactorily used in construction. . . . The 

 results of 2,500 individual routine tests made by the Office of Public Roads and 

 Rural Engineering show tluit for practical routine work the hardness test adds 

 nothing to our knowledge of the value of any particular rock sample for use in 

 water-bound macadam-road construction over that obtained from the toughness 

 test." 



The proper limits of toughness for light, moderate, and heavy traffic on 

 macadam and bituminous roads are discussed. 



The development of refined tars for use in road constniction and mainte- 

 nance, P. P. Sharples (Metallurg. and Chem. Engin., 13 (1915), No. 15, pp. 918- 

 920). — Specifications are given for (1) binders used in the construction of 

 macadam roads, (2) refined tars for use in road-blanket treatments, (3) re- 

 fined tars used in cold-surface treatments, and (4) pitches used as filler in block 

 pavements. 



