SCIENCE. 



[N. S. Vol. V. No. 127. 



The bed-rock series is, as usual, in places 

 covered by several hundred feet of Neocene 

 gravels and rhyolitic and andesitic tuffs, the 

 gently sloping top of the andesitic ridges form- 

 ing a principal feature of the landscape. 



The Neocene auriferous gravels have been ex- 

 tensively worked in the Nevada City and 

 Banner Hill districts, both by the drifting and 

 the hydraulic processes, and considerable 

 ground still remains which probably can be 

 profitably worked. The gold-quartz veins are 

 numerous and belong to several distinct sys- 

 tems. They are found in any of the formations 

 represented on the sheet, and generally cross 

 the contacts without change. In the Banner 

 Hill district the veins are narrow but rich, and 

 have a general east-west direction and a 

 northerly or southerly dip. In the Nevada 

 City district the quartz veins have a general 

 north-south direction and an easterly dip of 

 of about 45°. Large dislocations producing 

 over-thrust faults have occurred along several 

 of the veins. In the Grass Valley district there 

 is one system with a west-northwest direction 

 and a steep northerly or southerly dip. On 

 this system the celebrated Idaho mine is lo- 

 cated. Most of the veins in the central and 

 southern part of the district have a northerly 

 direction and a flat easterly or westerly dip. 

 The veins are often accompanied by strongly 

 developed sheeting of the country rock. 



SCIENTIFIC JOURNALS. 



AMERICAN JOURNAL OF SCIENCE. 



The June number begins with an article by 

 Theo. Holm, the fourth in a series of studies on 

 the Cyperacese. This contains a full morpho- 

 logical and anatomical study of the species 

 Didichium, and is illustrated by a page of fig- 

 ures. J. C. Branner discusses the subject of 

 bacteria in relation to the decomposition of 

 rocks. The literature of the subject is reviewed 

 and references given to various authors who 

 have believed that the bacteria played an im- 

 portant part in this direction. The author de- 

 cides, however, that it is highly improbable that 

 any considerable amount of rock decomposition 

 is due to this cause. J. H. Pratt and H. W. 

 Foote describe a new mineral species from the 



Corundum mine, of Buck Creek, Clay county, 

 North Carolina, to which they have given the 

 naxaewellsite, after Professor H.L.Wells, of New 

 Haven. The mineral belongs to the zeolites 

 and is a silicate of aluminum, barium, strontium 

 and calcium, crystallizing in the monoclinic 

 system. It is particularly interesting since it 

 forms another member of the Phillipsite group 

 to which the species Phillipsite, Harmotome and 

 Stilbite belong. 



Howard D. Day discusses the magnetic incre- 

 ment of rigidity of wires in strong magnetic 

 fields. The special subject discussed is "the 

 increase of resistance to torque produced by the 

 magnetization of twisted wires of various diame- 

 ters, when the magnetic field increases to many 

 times the amount needed to bring out the ordi- 

 nary magnetic saturation. The object of the re- 

 search was to make a clear comparison between 

 the phenomenon of magnetization or magnetic 

 intensity, on the one hand, and the phenomena 

 of magnetic rigidity on the other ; to show that 

 the two are quite distinct in character — that 

 the former practically subsides in relatively 

 weak fields, whereas the latter are not as fully 

 complete even in the highest fields applied." 

 The apparatus employed is described and fig- 

 ured, and the results presented in a series of 

 curves. It is seen that "as the fields become 

 stronger the increment of rigidity varies more 

 and more regularly with the twist, the tendency 

 being that in fields indefinitely large the in- 

 crement of rigidity would be proportional to the 

 twist applied." 



P. F. Schneider describes a geologic fault at 

 Jamesville, near Syracuse, N. Y. The interest 

 of the matter lies largely in the fact that this 

 region has been shown to be characterized by a 

 number of igneous dikes. H. L. Wells and H. 

 W. Foote have two articles on chemical sub- 

 jects, the first describing certain double halogen 

 salts of caesium and rubidium, and the second 

 being devoted to the double fluorides of zir- 

 conium with lithium, sodium and thallium. 



A. St.C. Dunstan, M. E. Rice and C. A. 

 Kraus give the results of some observations 

 made on the broadening of sodium lines by in- 

 tense magnetic fields. Their results confirm 

 the recently published work of Zeeman. They 

 state that using fields ranging from to 7800 



