238 CARNEGIE INSTITUTION OF WASHINGTON. 



and C. C. Ennis. Abstracts of contributions to scientific societies and 

 of articles published by them will be found on pages 259-268. 



It would seem to be now definitely established, as the combined 

 result of researches by various investigators, that the Earth's actual 

 magnetic state at any specified time is singularly dependent upon 

 solar conditions, and the problem of the ultimate causes is becoming 

 increasingly complex with advancement in knowledge. The want of 

 adequate facilities with which Nature's processes can be simulated 

 to a certain degree, at least, by laboratory experiment, is gradually 

 being filled since the erection of the Laboratory in 1914. Some of 

 these laboratory experiments will require a special non-magnetic struc- 

 ture for successful execution with the requisite refinement, entirely 

 apart from the non-magnetic standardizing observatory already on 

 the laboratory site. 



MAGNETISM IN GENERAL. 



The hope is entertained that means will soon be provided for the 

 new proposed structure, in which broad and fundamental investiga- 

 tions in magnetism, in general, may be conducted. The Department 

 is fortunate in having secured on July 1, 1918, as the person to conduct 

 this important experimental work. Dr. S. J. Barnett, formerly pro- 

 fessor of physics at the Ohio State University. Dr. Barnett is well 

 known for his successful experiments on magnetization by rotation; 

 he has also had practical experience in terrestrial magnetism, having 

 been a magnetic observer when the Director was in charge of the 

 magnetic work of the United States Coast and Geodetic Survey. 

 Since the assumption of his duties in the Department he has been 

 engaged in the necessary preparations for the coming experimental 

 work and in the designing of apparatus; he has also taken part in the 

 investigations mentioned in the first paragraph of this section. He 

 hopes to continue his experimental work on magnetization by rotation 

 with better facilities and with such refinement that it will be possible 

 to show conclusively whether the positive electrons contribute any- 

 thing appreciable to the Ampereian currents. The experiments on 

 magnet-photography, of which a preliminary account was given in the 

 annual report for 1917 (pp. 254-255), have been resumed, using more 

 intense magnetic fields and otherwise modified conditions. 



TERRESTRIAL ELECTRICITY. 



The investigational work in atmospheric electricity and earth cur- 

 rents has been mainly conducted by the observatory division under the 

 charge of J. A. Fleming as chief of the division and S. J. Mauchly, 

 assistant chief, Dr. W. F. G. Swann having resigned his post at the 

 end of 1917 to accept a professorship in physics at the University of 

 Minnesota. Some mention of the work under this head will be found 



