706 



SCIENCE 



[N. S. Vol. XLIII. No. 1116 



THE WORK OF THE JEFFERSON 

 PHYSICAL LABORATORY 



A SYNOPSIS of all the scientific investigations 

 which have been carried on in the Jefferson 

 Laboratory since its foundation in 1884 is 

 beyond the scope of a brief notice. On the 

 other hand, it is impossible to give a picture 

 of our activities without a review of an extent 

 sufficient to include the beginnings of those re- 

 searches which are still in progress. Fortu- 

 nately, it will not be necessary to go into much 

 detail of description, since the eleven voliunes 

 of our " Contributions " contain a full ac- 

 count of all the results which have been ob- 

 tained in the last dozen years. 



The fact that this laboratory is not domi- 

 nated by the work of any one man has led to 

 a breadth of field in investigation rarely found 

 in other similar institutions. The very num- 

 ber and variety of subjects, however, makes it 

 difficult for a single individual to give an ade- 

 quate account of the work as a whole. I have 

 been freed from this difficulty by my col- 

 leagues. Professors Hall, Sabine, Davis and 

 Bridgman, who have been kind enough to edit 

 the account of their own researches. 



Professor Hall's research work for many 

 years has had to do with the flow of electricity 

 and of heat in metals. He has published, 

 usually in cooperation with others, various 

 papers on thermal conductivity, on the Thom- 

 son effect, and on the electromagnetic and 

 the thermomagnetic transverse or longitudinal 

 effects in iron. Of late he has been occupied 

 especially with the theories of electric and of 

 thermal conduction, and of thermoelectric ac- 

 tion, in metals. On this subject he published 

 a paper in 1914, reaching the conclusion that 

 " free electrons " play a much smaller part in 

 conduction than many have supposed, but have 

 an important function in thermo-electric 

 action. In 1915, he published in II Nuovo 

 Cimento a short paper suggesting that the 

 positive ions in a metal, probably as numerous 

 as the free electrons, may have much to do in 

 the maintenance of an electric ciirrent. He 

 is now engaged in developing this idea. 



Professor Sabine is continuing his investi- 

 gations in the varied problems of architectural 



acoustics. The results, so far published, are 

 proving of value to architects in the correction 

 of auditoriums and in their design in ad- 

 vance of construction. At present the experi- 

 ments relate to the transmission of sound 

 through the structure. While Professor 

 Sabine has been working in one field he has 

 stimulated a number of students in a variety 

 of different subjects. Some of the researches 

 for which he was originally responsible are 

 still in progress; of these the work of Pro- 

 fessor Bridgman and the investigations in the 

 Schumann region will be mentioned in detail 

 presently. 



The work of Professor G. W. Pierce on 

 high-tension currents was for many years 

 carried on in this laboratory. It is, there- 

 fore, a great temptation to add interest to this 

 notice by including an account of it here. 

 However, as Professor Pierce is now under 

 his own roof, it seems only fair. to allow him 

 to describe the activities of his own laboratory, 

 should he care to do so, at some future time. 



Notwithstanding that a large part of the 

 time of Professor Duane is taken up at the 

 Huntington Hospital by his work on the ap- 

 plication of the radiations from radioactive 

 substances to the treatment of cancer, he is a 

 most active contributor to the research output 

 of this laboratory. He has himself written 

 several articles, theoretical and experimental, 

 on the subject of X-rays, Radioactivity and 

 Atomic Theory during the past year and he 

 is at present directing the experiments of four 

 students in the same fields. 



The establishment of standards of wave- 

 length and the study of the emission of gases 

 and solids in the Schumann region has occu- 

 pied me for the last fifteen years; recently I 

 have succeeded in extending the spectrmn, in 

 the extreme ultra-violet, beyond the limit set 

 by Schumann by an amount greater than that 

 which Schumann achieved. There stiU re- 

 mains, however, a considerable gap to be 

 bridged before the region of the softest X-rays 

 is reached. Researches on the abiotic action 

 of Schumann rays and a study of the volmne 

 ionization produced by them, have been com- 

 pleted in years past by Dr. Bovie and Pro- 



