420 



SCIENCE. 



[N. S. Vol. IX. No. 220. 



The paper concludes with a general discus- 

 sion of the experimental data, which may be 

 summarized as follows : 



The permeability and induction are always 

 smaller for an alternating field than for a steady 

 one, the difference reaching a maximum for 

 low values of the magnetizing force, while near 

 saturation the difference is small. For low 

 values of the magnetizing force the differences 

 are the same for all frequencies. The softer 

 and less subdivided the iron, and the higher the 

 frequency, the greater the difference (amount- 

 ing in one case for very soft iron to 40%). 



In moderate and strong fields, for equal values 

 of the induction, the hysteresis is greater for 

 alternating magnetization, than the value ob- 

 tained by the usual static methods, the increase 

 being greater the nearer saturation is ap- 

 proached, the higher the frequency and the softer 

 the iron. The opposite is true for weak fields. 



The only explanation which can be given is 

 that the magnetism of the iron is unable to keep 

 up with a rapidly varying field and consequently 

 the hysteresis loop is broader and lower than 

 it would be if determined for slow changes of 

 the field. A. St. C. D. 



GENERAL. 



H. Bbcqubrel (Comptes Rendus, t. CXXVIL, 

 p. 899 and t. CXXVIIL, p. 145) has been able 

 to prove and study the existence of abnormal dis- 

 persion in sodium vapor. He finds that the 

 effects of the Di and D, lines in causing ab- 

 normal dispersion are superposed and that for 

 certain rays the refractive indices are less than 

 unity. 



On account of its importance in the theory of 

 atmospheric electricity the question as to 

 whether the vapor of an electrified liquid is 

 itself electrified is of great interest. It cannot 

 be said that the subject has not received atten- 

 tion, but the results obtained by different inves- 

 tigators are not in accord. Pellat (Oomptes 

 Kendus, t. CXXVIIL, p. 169) has lately re- 

 investigated the subject and finds that the 

 rate of loss of charge from an insulated, 

 electrified, metal vessel is greater when it 

 contains water than when empty. Applying 

 this result to the phenomena of atmospheric 

 electricity he comes to the conclusion that it can 



only explain a part of the observed facts and 

 further knowledge will reveal some as yet un- 

 known cause acting. A. St. C. D. 



SCIENTIFIC NOTES AND NEWS. 

 Mr. Henry Gannett, Geographer of the 

 Geological Survey, who was the political and 

 statistical geographer of the last census, has been 

 asked to take charge of the same work for the 

 coming census. The Director of the Census, 

 Mr. Merriam, has announced that all applica- 

 tions for positions will receive consideration, and 

 that examinations will be held as rigid as those 

 before the Civil Service Commission. The 300 

 Supervisors are to be appointed after consulta- 

 tion with Senators and Representatives of the 

 separate States, but without regard to party 

 affiliations. 



The professors of geology in the University of 

 California and in Stanford University have or- 

 ganized a geological club, to be called the ' Cor- 

 dilleran Geological Club.' It is intended to 

 include all the geologists of the Pacific and ad- 

 jacent States, and its object is by occasional 

 meetings to stimulate geological work. Whether 

 it shall remain an independent organization or 

 shall be affiliated with any other scientific body 

 is left for future decision. 



Professor Ray Lankester has been elected 

 Foreign Correspondent of the Paris Academy 

 of Sciences for the Section of Anatomy and Zo- 

 ology. Twenty-seven votes were cast for Pro- 

 fessor Lankester and eight for Professor Van 

 Beneden, of Liege. M. Lortet, professor of 

 medicine, of Lyons, has been elected National 

 Correspondent for the same Section. 



Lord Lister, London, and Professor Koch, 

 Berlin, have been elected Foreign Associates of 

 the Paris Academy of Medicine. 



Professor Ray Lankester, London ; Pro- 

 fessor L. Cremona, Rome, and M. Alexander 

 Karpinsky, St. Petersburg, have been elected 

 Associates of the Belgian Academy of Sciences. 



The address in medicine at the next Yale 

 commencement exercises is to be delivered by 

 Professor Charles Sedgwick Minot, of the Har- 

 vard Medical School. The title of the address 

 has not yet been announced, but we are in- 



