DEPARTMENT OF TERRESTRIAL MAGNETISM. 231 



INVESTIGATIONAL WORK IN WASHINGTON. 



The general investigational work, theoretical and experimental, conducted 

 during the year in the Department's laboratory at Washington by the Divi- 

 sion of Investigational Work, under the Director's charge, was as follows : 



TERRESTRIAL MAGNETISM AND ELECTRICITY.^ 



Analysis of the Earth's magnetic field for 1922, by the Director, assisted 

 by Messrs. W. J. Peters, C. R. Duvall, C. C. Ennis, and Miss Emma L. 

 Tibbetts (see abstract, pp. 248-249). 



Magnetic data and charts for polar regions. — The reductions concerned with 

 the analysis of the Earth's magnetic field showed it to be highly important 

 to obtain additional magnetic data for the higher latitudes, both as regards 

 the distribution of the magnetic elements and their secular changes. Accord- 

 ingly, all available data, for stations north of latitude 50° and south of lati- 

 tude 40°, were assembled by Messrs. Peters and Duvall and put in tabular 

 form preparatory to the construction of improved magnetic charts for the 

 polar regions, as soon as the attempt may be warranted. 



Further investigation concerning line integrals of the magnetic force. — See 

 abstracts, pages 252 and 265. 



Relationships between terrestrial magnetism, terrestrial electricity, and sun- 

 spot activity. — The studies under this head have been continued and a report 

 on the chief results obtained has been prepared for publication (see abstract, 

 p. 249). 



Measure of the Earth's 7nagnetic activity. — See abstract, page 249. 



Publication and lecture work. — Good progress was made with various special 

 reports to be published as a volume of the "Researches of the Department." 

 For publications in scientific periodicals and papers before scientific socie- 

 ties, see abstracts on pages 246-266. 



Besides the lecture referred to on page 229, the Director gave a lecture on 

 "The general phenomena and theories of the Earth's magnetic field" at 

 the Standardization Laboratory of the General Electric Company at West 

 Lynn, Massachusetts, March 30, 1923, and another on "The present status 

 of our knowledge regarding the constitution and the causes of the Earth's 

 magnetic field" on March 31 at the Research Laboratory of the General 

 Electric Company at Schenectady, New York. 



Miscellaneous. — Numerous conferences were held with eminent physicists 

 on various problems pertaining to terrestrial magnetism and atmospheric 

 electricity. On December 8 and 9, 1922, the Director took part, on the 

 invitation of President Merriam, in a conference on the origin and nature 

 of cycles, held at the Carnegie Institution of Washington. 



EXPERIMENTAL WORK IN MAGNETISM.^ 



Magnetization by rotation. — Dr. Barnett has been occupied almost entirely 

 with the continuation of the investigation on magnetization by rotation. 

 Much labor has been devoted to reducing the accidental errors, and especially 

 the residual systematic errors. With this object in view, considerable im- 

 provement has been made in almost every part of the apparatus. In 

 addition to extended observations on some of the ferromagnetic substances 



1 From the reports of Louis A. Bauer and W. J. Peters. 

 ^ From the report of the chief of the section, S. J. Barnett. 



