386 EXPERIMENT STATION EECORD. 



by the transplantable mammalian tumors, and traceable to the changes in a 

 single strain of tumor cells during their propagation in successive hosts. In 

 mammals the ultimate reason for these changes is not linown. In the case of 

 the chicken tumor some of them are undouljtetlly the expression of changes in 

 the growth's causative agent." 



RURAL ENGINEERING. 



Third biennial report of the department of engineering of the State of 

 California {Bien. Rpt. Dept. Engin. Cal., 1910-1912, pp. 263, pis. 56).— This is a 

 progress report of engineering operations from 1910-1912, including engineering 

 service at state institutions and state buildings, laboratory testing, state high- 

 ways and bridges, irrigation, river and harbor improvement, water resources, 

 and power development. 



Construction of the Kachess dam, Washington, E. H. Baldwin (Engin. 

 Neics, 69 (1913), No. 20, pp. 989-999, fig^. 11). — An account is given of the con- 

 struction of an earth dam G5 ft. high and 1,400 ft. long built by .he United States 

 Reclamation Service across the Kachess River a short distance below Kachess 

 Lake to increase the storage capacity of the lake for irrigation purposes. Novel 

 features of the work were the dredging of a channel from deep water in the 

 lake toward the dam, the construction of a reenforced concrete conduit from 

 the lower end, of the dredged channel to a point near the dam, an intake tower, 

 a reenforced concrete conduit through the dam, a spillway far to one side, the 

 use of dump cars and a high trestle for bringing the earth to the embankment, 

 and the use of a high timber concrete elevating tower in building the outlet 

 tower. 



A method of proportioning concrete, W. B. Hunter {Engin. 'News, 69 {1913), 

 No. 19, pp. 956-95S, figs. 3). — The results of studies and actual tests of several 

 methods of proportioning the ingredients of concrete are given from which the 

 following method is adopted to insure a satisfactory quality of concrete and 

 avoid the use of an excess of cement : Make a careful mechanical analysis of 

 the aggregates by determining the amount of cement in excess of the voids in 

 the fine aggregate required to make an acceptable mortar and the amount t>f 

 mortar in excess of the voids in the coarse aggregate required to make an 

 acceptable concrete. After determining the percentage of voids in the aggre- 

 gates proportion the ingredients so as to fulfill these requirements. 



Three sets of curves are given to aid in the use of this method. 



Effect of too much water in mixing concrete {Engin. News, 69 (1913). No. 

 21, p. 1063, fig. 1). — Bending and compression tests were made by C. J. Robisou 

 at Yale University on cubes and beams of a 1 : 2 : 4 concrete, consisting of normal 

 sand, cement, and f-in trap rock. The minimum mixture contained 20 per cent 

 of water by the weight of the cement and each subsequent mixture was in- 

 creased by 2* per cent of water until a mixture containing 42^ per cent of water 

 was reached, which was of about the consistency of the average wet mixture. 



The beam tests showed that keeping everything constant except the water 

 there was a gain in strength of 126 per cent for a 27i per cent over a 20 per cent 

 water content at the end of 30 days and 126§ per cent at the end of 60 days. 

 The cube tests showed a gain of 282 per cent with the 27* per cent water con- 

 tent over the 42* per cent at 7 days, 138 per cent at 30 days, and 90 per cent at 

 60 days. The tests as a whole indicate that in time a drying out will somewhat 

 reduce the handicap of a A-ery wet mixture. 



The protection of concrete structures from alkali and other destructive 

 agents, W. D'Rohan {Engin. and Contract., 39 {1913), No. 21, pp. 570, 571).— 

 From the results of his 3 years' experimental work in the alkali regions of 



