1020] RURAL ENGINEERING. 281 



It is concluilod that in pi-iutiial dam construction one should "study hy 

 l)niiii;:.s the actual consolidation of the material and adjust the construction 

 <>{' the upper parts of the dam to tlie demonstrated condition of that wiiich 

 lies below. Make the toes large enough to resist witii an ample factor of safety 

 the whole pressure of the core material as a liquid until there is demonstration 

 of the solidification of the core to a point where horizontal pressure is elim- 

 inated. Increase the weight and solidity of toes by the use of rock fill placed 

 hydraulically or otherwi.so. 



" Stability is increased by compactness. It is worth while to watch voids 

 closely and to make every effort to hold them at a minimum. The extra weight 

 is advantageous, but security against compression and rearrangement with 

 resulting temporary quicksand conditions can be best reached in this way." 



The record of 100 dam failures, L. Jorgensen {Jour. Electricity, Jf.'f 

 (1920), Nos. 6, pp. 21Jt-216; 7, pp. 320, 321, figs. 5). — A list is given of more than 

 100 dams that have failed, including a short description of when and why they 

 failed and in most cases their principal dimensions. All conceivable types of 

 dams are included in the list with the exception of pure arch dams. It is 

 staled that earth-fill dams fail quite frequently, apparently because in most 

 cases water goes over the crest or sweeps under the cut-off wall. Rock-fill dams 

 fail for similar reasons, while reinforced-concrete dams generally have failed 

 by the water imdermining the structure. 



Protection of inclined soils against the washing of rain and irrigation 

 waters, S. Caldieri (Rev. Ayr., Com., y Trab. [Cuba], 2 (1919), Nos. 9, pp. 

 432-J,36; 10, pp. 50Jf-508; 11, pp. 565-570, figs. 31).— This is a translation by 

 A. Brambila of an article describing the Italian system of protecting sloping 

 soils against washing and excessive erosion by irrigation and rain water by 

 the use of terraces and ditches. 



Control of Avater on hills, L. Fronzi (Coltiratorc, 66 (1920), Nos. 6, pp. 

 154-158; 7, pp. 182-186, figs. 5). — Italian practice in the prevention of erosion 

 in hilly soils by terracing and ditching is reviewed. 



Investigations in adapting the automobile to accurate soil survey and 

 road traverse work, \V. T. Carter, jr., J. F. Stroud, and T. M. Bushnell 

 (Texas Sia. Circ. 19 (1919), pp. 3-9, figs. 6).— Methods used by the Texas Soil 

 Survey, in cooperation with the Bureau of Soils of the U. S. Department of 

 Agriculture, in the use of an automobile iu soil survey work, are described 

 and illustrated. The most successful device for making surveys consisted of 

 a wheel running alongside of the car with an attached odometer which can be 

 read from the car seat. 



Experiments on the value of common rock salt and sulphur for killing 

 live stumps, W. Ruuolfs (Soil Sci., 9 (1920), No. 3, pp. 181-189, figs. //).— Ex- 

 periments conducted at Rutgers College are reported, which showed that appli- 

 cations of sulphur on high or low oak brush as a means of clearing land for 

 agricultural purpo.ses is of no value. Instead, sulphur seemed to have a stimu- 

 lating effect upon the growth of live tree stumps. 



Common rock salt, when applied to oak stumps which had been allowed to 

 grow for several years, did not do much harm when applications of from 2- to 2^ 

 tons per acre were given. When applied in amounts of ii to 1 ton per acre 

 these shrubs were stimulated, the salt acting as a fertilizer. In cases where 

 trees had been cut in winter time and the brush burned at the place, the stumps 

 were much retarded in their growth by applications of salt at the rate of 

 i to li tons per acre. When applications of 2 to 3 tons per acre were made, 

 stumps of white oak and black oak were killed or so severely injured that 

 death resulted. The best time to make salt applications is in the spring, just 



