June 4, 1921 abstracts: geoi^ogy and hydrology 2o9 



CONCLUSION 



It can be concluded that the causes or sources of fading and of 

 strays are in the atmosphere between the earth's surface and the Heavi- 

 side surface. However, the origin of these causes, in turn, is un- 

 doubtedly from below the ground or from outside of the earth's at- 

 mosphere. 



Daytime transmission is effected entirely by means of the waves 

 carried along the ground, while night transmission, especially at great 

 distances and on short waves, is by means of waves transmitted along 

 the Heaviside surface. The latter, at night, are thus free from the 

 absorption to which ground waves are subject in the daytime. They 

 are, however, subject to great variations, caused by irregularities in 

 the Heaviside surface and absorbing masses of more or less ionized 

 air at or near that surface. These variations account for fading. 



The theory here given may be only a very rough approximation 

 but it has the advantage of giving a clearer picture than has been 

 available. The inter-relation of radio phenomena and the atmos- 

 phere's electrical condition is very close. Subordinate in importance 

 to the atmospheric conductivity are the other electrical properties, 

 the solar constant, and the terrestrial magnetic and meteorological 

 conditions. The properties of the stratosphere seem to be far more 

 important than those of the troposphere, since the stratosphere seems 

 to be the seat of the immediate causes of the observed radio trans- 

 mission phenomena. 



ABSTRACTS 



Authors of scientific papers are requested to see that abstracts, preferably prepared 

 and signed by themselves, are forwarded promptly to the editors. The abstracts should 

 conform in length and general style to those appearing in this issue. 



GEOLOGY AND KYBROLOGY. —Ground water in Pahrmnp, Mesquite, and 

 Ivanpah valleys, Nevada and California. Gerald A. Waring. U. vS. 

 Geol. Survey Water-Supply Paper 450-C. Pp. 30, pis. 5, figs. 2. 1920. 

 The report comprises a geographic and geologic sketch and a discussion of 

 the ground waters of the regions named. The valleys consist of detached 

 basins with interior drainage, mountain-rimmed and deeply filled with al- 

 luvium. Alluvial fans slope, from the mountain areas and grade into the 

 playas which occupy the lowest portions of the basins. Springs occur in all 

 of the valleys, and artesian flows have been obtained in Pahrump Valley. 

 Records of springs and wells are included in the report, and also a brief state- 

 ment of the quality of the water. The extent of irrigation already practiced, 

 the possibilities of further irrigation development, and the limits of agricul- 

 tural projects are discussed. N. E. D. 



