248 



SCIENCE 



[N. S. Vol. LII. No. 1341 



a school of public health and hygiene in the 

 medical department of the University of 

 Georgia, Augusta. 



De. Arthur S. Hathaway, since 1891 pro- 

 fessor of mathematics at the Rose Polytechnic 

 Institute, has retired from active service. He 

 is succeeded by Dr. I. P. Sousley, of Penn- 

 sylvania State College. 



Professor Feederick Slocum has returned 

 to Wesleyan University as professor of astron- 

 omy and director of the Van Vleck Observa- 

 tory. 



Me. Guy R. McDole, assistant soils chem- 

 ist in the Minnesota Agricultural Experiment 

 Station, has accepted a position as associate 

 professor of agronomy and soil technologist 

 at the University of Idaho. 



Dr. Robert Stewart, who has for the past 

 five years been associated with the late Dr. 

 Cyril G. Hopkins at the University of Illinois 

 as professor of soil fertility, has resigned his 

 position to accept the deanship of the college 

 of agriculture of the University of Nevada. 



Dr. Aethue T. Evans has accepted the posi- 

 tion as associate agronomist in South Dakota 

 State College and Experiment Station. He 

 has previously been professor of botany and 

 dean at Huron College ; and earlier engaged in 

 corn disease investigations with the Cereal 

 Office of the United States Department of 

 Agriculture. 



Dr. Wm. Conger Morgan has resigned his 

 position as professor of chemistry at Reed 

 College to become professor of chemistry at 

 the Southern Branch of the University of 

 California at Los Angeles. 



C. Lee Shilliday, professor of anatomy and 

 histology in the college of dentistry, Univer- 

 sity of Tennessee, has accepted the professor- 

 ship of biology in the Pennsylvania College of 

 Gettysburg, to succeed Dr. George Stahley, 

 who has retired after thirty years' service. 



Associate Peofessoe Burt P. Bjrkland, and 

 Assistant Professor E. T. Clark, of the college 

 of forestry and lumbering of the University 

 of Washington, have been promoted, the former 

 to a full professorship and the latter to an 

 associate professorship. 



De. William Boyd, professor of pathology 

 in the University of Manitoba, Winnipeg, has 

 declined the offer of the chair of pathology at 

 the medical school, Cairo, Egjrpt. 



De. Friedmann, the value of whose turtle 

 vaccine for tuberculosis is questioned, has been 

 appointed extraordinary professor at the ITni- 

 versity of Berlin against the vote of the med- 

 ical faculty. 



Dr. a. Gosset, professor of external pathol- 

 ogy of the Paris medical faculty, has been ap- 

 pointed to the chair of clinical surgery left 

 vacant by the retirement of Professor Quenu, 

 and Dr. Vaquez, professor of internal pathol- 

 ogy, has been appointed to succeed Professor 

 Robin in the chair of clinical therapeutics. 



DISCUSSION AND CORRESPONDENCE 



A BAND SPECTRUM FROM MERCURY VAPOR 



To THE Editor of Science: The writer has 

 recently observed that under certain conditions 

 the discharge through mercury vapor gives 

 a glow that is distinctly green. An examina- 

 tion of this glow shows the ordinary line spec- 

 trum of mercury together with a spectrum 

 which is apparently continuous through nearly 

 all of the visible spectrum, being most promi- 

 nent in the green. So far as the writer has 

 been able to learn there is no record of such a 

 spectrum having been obtained from the dis- 

 charge through mercury vapor. 



Two conditions are necessary for obtaining 

 this spectrum vnth any considerable bright- 

 ness. First the vapor through which the dis- 

 charge takes place must be passing from a 

 hotter to a colder region, as from the mercury 

 arc or from the mercury heated by a flame to 

 a condensing chamber, that is, through vapor 

 that is condensing. 



Secondly the voltage must be kept as low 

 as possible and yet have a discharge. As the 

 voltage is raised the ordinary line spectrum 

 becomes more prominent and the continuous 

 spectrum less so. The discharge from a Wim- 

 hurst machine or from a transformer shows 

 the glow somewhat better than that from an 

 induction coil. Putting condensers in parallel 



