560 



SCIENCE 



[N. S. Vol. XXXVII. No. 954 



Elmer Keiser Bolton, for research in chemistry 

 at Berlin. 



Richard Maurice Elliott, for research in psychol- 

 ogy, particularly in the psychophysies of hand- 

 writing, at Berlin and in the various psychological 

 laboratories of Germany. 



Harvey Cornelius Hayes, for travel in the 

 United States, between September and February, 

 for the purpose of observing the manufacture of 

 alloys. 



Sidney Isaac Kornhauser, for research in zool- 

 ogy at Wiirzburg and at the Naples Zoological 

 Station. 



Edward Hale Parry, for travel in the mining 

 districts of the United States during the summer 

 of 1913. 



Joseph Slepian, for research in mathematics in 

 Europe. 



Paul Dudley White, for research in pharmacol- 

 ogy at London and Strasburg. 



Professor Ernest J. Berg, of the depart- 

 ment of electrical engineering of the Univer- 

 sity of Illinois since 1909, has resigned that 

 position to return to a similar position at his 

 alma mater, Union University, at Schenect- 

 ady, N. T., and also to become consulting 

 engineer of the General Electric Company of 

 that city. 



Professor E. W. Thatcher, director of the 

 Washington Agricultural Experiment Sta- 

 tion and head of the department of agricul- 

 ture of Washington State College, has been 

 elected professor of agricultural chemistry 

 and soils in the University of Minnesota, the 

 appointment becoming effective on May 1. 



DISCUSSION AND COBBESFONDENCE 



ELECTROMAGNETIC INDUCTION AND RELATIVITY 



To THE Editor of Science: In the last 

 number of Science (March 14) Professor A. 

 L. Kimball expresses the opinion that my 

 recent experiments on electromagnetic induc- 

 tion are " not so definitely in contradiction to 

 the principle of relativity as may appear at 

 first sight," basing his conclusion on the fact 

 that in certain cases the indication of a meas- 

 uring instrument depends upon the manner in 

 which it is connected to the apparatus under 

 test. 



This is a very important point, but it is 

 naturally one which I had not failed to con- 

 sider with great care. That no fallacy was 

 made in reaching my conclusion will be evi- 

 dent, I think, from what follows. 



Case I. — In my own recent experiments the 

 cylindrical condenser, with its armatures A 

 and B connected together by a wire C, re- 

 mained at rest while the agent producing the 

 magnetic field, whose direction was parallel to 

 the common axis of the two cylinders, was 

 rotated. The short-circuit by the wire C was 

 then interrupted, leaving the inner conductor 

 B completely insulated. After the rotation 

 was stopped and the field annulled, B was 

 tested for charge by connection to an elec- 

 trometer. No charge was detected. 



Case II. — Now imagine the condenser, to- 

 gether with its short-circuiting wire C, to 

 rotate while the agent producing the magnetic 

 field remains fixed to the earth. If the wire 

 C is now interrupted, leaving B completely 

 insulated from A, and if the condenser is then 

 brought to rest and the field annulled, the 

 cylinder B, tested exactly as in Case I., will 

 he found charged. While the experiment in 

 this form has not been made, the result given 

 is an immediate and necessary consequence of 

 the experiments by Paraday and others re- 

 ferred to in my earlier article. For no one 

 will contend that in this case the seat of the 

 motional electromotive force is elsewhere than 

 in the wire C and in the dielectric, if any, 

 entrained by the conductors in their motion. 

 Moreover, that the ether is not entrained, and 

 that the entrainement of any air would pro- 

 duce no appreciable effect, are facts which fol- 

 low from some of the experiments (those on 

 insulators) already referred to. In addition 

 to these considerations only one assump- 

 tion is necessary to the argument, viz., the 

 assumption that an electric charge of one sign 

 on an insulated conductor is not altered by 

 being brought to rest from a state of motion. 



Thus the condenser is actually charged in 

 one case and not charged in the other, the rela- 

 tive motion in the two cases being exactly the 

 same. If complete relativity existed, the con- 

 denser, tested in the way described, would be 



