484 KXPEIUMEXT STATION KECORD. 



6"). — A report of field studies made in the region iiu-luding Owens Valley, part 

 of Mono Lake and Salt Wells Valleys, and the slopes of the adjoininj; mountain 

 ranges. The conclusions bearing upon irrigation are as follows : 



'■ Owens Valley is a barren desert except where it is i-eclaimed by the use of 

 water entering as mountain streams. Abundant rainfall occurs in the Sierra 

 Nevadas, yielding for this valle.v an annual water supply of about 400,000 acre- 

 feet. As the streams enter the valley, the.v iiass over unconsolidated detritus, 

 into which much of the water sinks. 



" Flowingwells occur in Owens Valley, but the limits of the district in whicli 

 such wells are obtainable are undetermined, 



"A large amount of underground water exists without hydrostatic pressure 

 sufficient to produce flowing wells, but power for inimping this water can be 

 produced from the mountain streams and transnntted to the valley at moderate 

 cost, 



"Owens Lake has been decreasing in volume for several years, with a 

 corresponding increase in the density of its water. The salinit.v has reached a 

 point at which the more insoluble salts precipitate. The change is probably 

 due to the loss by evaporation of water diverted for irrigation and not to an 

 increase in the aridity of the climate, as originally supposed. 



" The proposed Owens Valley reservoir, being located in the fault zone at the 

 base of the Sierra Nevada, would l)e especially liable to injury from crustal 

 movements. ■■ 



Turbine water-wheel tests and power tables, R. E. Horton ( V. 8. Geol. 

 Survey, Water-Supply and Irrlg. Paper Xo. i.SO, pp. 131, pis. .}, figs. 33). — A 

 discussion of turbine water wheels, with special reference to their use as 

 water meters. Various types of wheels are described, results of various tests 

 ai*e given, and manufacturers' tables of jiower, speed, and discharge are 

 included. 



The development of the test for the cementing value of road material, A. S. 

 CusiiM.\x (Ent/iii. h'rc, o3 (1006), Vo. i.*, pp. 76>>-762). — A paper read liefore 

 the American Society for Testing Materials. 



The author reviews the earlier attempts to develop a test for the cementing 

 values of the dust of abraded material. These first tests consisted in general of 

 mixing road dust with Avater and molding the dough into small briquettes, which, 

 after being dried, were tested to destruction by repeated impacts of a hammer 

 weighing 1 kg. and falling 1 cm. Certain disci-epancies having been found in 

 the results obtained by this method, more care was taken in the mixing. It was 

 found that the binding power could be increased by prolonged kneading, cor- 

 responding to the characteristics of dolomite in actual use, the binding power 

 of which has been observed to increase after it has been on the road some time. 

 Later still, a method of wet grinding was introduced, the " charge of rock dust 

 being ground with api)roxin]ately 20 per cent by weight of water in a ball mill 

 for ?> hours." By this method the binding power was increased, confirming the 

 idea general among road engineers that the more wet rolling to which tlie rock- 

 road material can be sub,iected, the better the resulting I'oad. 



The latest developments in grinding are porcelain pebble mills which have 

 been substituted for the heavy and cumbersome ball mills. A recent series of 

 experiments has developed a field of investigation which, according to the author 

 " promises to be of great interest both on the theoretical and practical sides." 

 " It appears that the addition of lime or limestone will greatl.v increase the 

 cementing value of an acidic rock like granite." The results that are shown in 

 the table were obtained by mixing together limestone and granite rock powders 

 of known cementing value and grinding the mixture with water . 



