METEOEOLOGY WATER. 511 



"A survey of this character is woi'th mucli more than the certainty It gives 

 the irrigator regarding the future of his crop or the knowledge as to what crop 

 he should plant. It eliminates his products from that class whose amount of 

 production is more or less problematical. It tends to steady prices and, iu 

 addition to the taking away of these uncertain features, gives a crop, although 

 not matured, a money value which it would not have, to such a great measure 

 at least, if the water supply were not known." 



The winds of the United States and their economic uses, P. C. Day ( U. S. 

 Dept. Agr. Yearbook 1911, pp. 337-350, pis. 7, figs. 2). — This article contains 

 and discusses a series of charts " showing the average hourly velocities of the 

 wind and its direction throughout the various portions of the country and for 

 special months of the year and hours of the day, with diagrams indicating the 

 daily march of the winds and their variations at different levels." The data 

 from which these charts were prepared are based mainly upon records for the 

 20-year period, 1891 to 1910, inclusive. 



The economic use of the wind in windmills, for production of electrical energy, 

 and in aviation is briefly discussed. 



A more detailed paper on the subject is in course of preparation. 



Subsoil water of central United States, W J McGee {U. S. Dept. Agr. 

 Yearbook 1911, pp. Ji79--'i90). — This article is based upon data obtained through 

 the crop reporters of the Department of Agriculture, and deals specifically with 

 changes in level of water in wells iu Illinois, Indiana, Iowa, Kentucky, Michi- 

 gan, Minnesota, Missouri, Ohio, Tennessee, and Wisconsin. 



" The number of wells showing change in water table ranges from 64.9 per 

 cent in lower Michigan and 62.3 per cent in Wisconsin to 31.3 per cent iu Mis- 

 souri, averaging 52.1 per cent. The average lowering of water table during the 

 period of observation ranges gradually down fi'om 3.87 ft. in Wisconsin and 3.45 

 In Minnesota to 1.94 ft. in Tennessee, and then drops to only 0.95 ft. in IMis- 

 souri. . . . The mean rate of lowering per decade for the 9 States excluding 

 Missouri (1.315 ft.) is equivalent to a total lowering of 10.5 ft. in the 80 years 

 which have elapsed since permanent settlement and cultivation began to extend 

 into Illinois and Wisconsin and on into Iowa and Missouri." Although part of 

 the lowering may be ascribed to special causes, " it seems clear that the records 

 broadly indicate a secular lowering of the subsoil-water level, presumably due 

 to clearing and cultivation of the land. . . . 



" The results are in accord with common knowledge — of the failing of springs 

 and wells following settlement, of the dwindling and disappearance of brooks, 

 of the advancing destruction by floods due to increased surface run-off during 

 and after storms, of the increasing difliculty in obtaining domestic water supply 

 for farms, villages, towns, and cities, of the steadily growing danger of crop 

 loss through drought, of the increasing need for irrigation in the humid section." 



On the transport of mud by a river in flood, T. Steel (Cliem. News, 105 

 (1912), No. 27Jio, p. 290). — This note gives observations on the amount of mud 

 carried by the River Yarra, Victoria, in flood, and the composition of mud car- 

 ried by the Tweed Eiver, New South Wales, in flood. The latter showed on the 

 basis of dry matter 1.16 per cent lime. 0.2 per cent potash, 0.36 per cent phos- 

 phoric acid, and 0.48 per cent nitrogen. 



Experiments on the removal of manganese from ground water, Thiesing 

 (Mitt. K. PriifKngsamt. Wasserver. u. Ab-wdsser. Berlin, 1912, No. 16, pp. 210- 

 296, figs. 16). — From the results of these experiments the author concludes that 

 manganese in the form of carbonate can be easily removed by aeration and fil- 

 tration. The methods and precautions to be observed are fully discussed. 



Influence of the hardness of water on its suitability for drinking purposes 

 (Prometheus, 23 (1911), No. 1157, p. 207; abs. in Wasser u. Abwasser, 5 (1912), 



