DEPARTMENT OF TERRESTRIAL MAGNETISM. 245 



Experimental work. — Three-quarters of the time devoted to experimental 

 apparatus was in connection with the equipment for the special investigation 

 by Dr. Barnett on magnetization by rotation (see p. 247). Other experimental 

 work included parts and apparatus for the proper designing of atmospheric- 

 electric instruments and equipment for field and observatory use and the 

 assembling for test of standard conductivity apparatuses 7 and 8 for observa- 

 tory use. A 90-pound, nonmagnetic brass bedplate for the equipment in 

 the experiment building was cast in the Department's foundry, and over 

 1,200 nonmagnetic brass and bronze castings for magnetometer inductors 

 of Department design were made in a local foundry under the supervision 

 of the shop foreman. 



Improvements and repairs. — All instrumental equipments for the field 

 parties dispatched during the year (see report on field operations), including 

 those for the party of the Liberian boundary survey and the extensive mag- 

 netic and electric equipments for the MacMillan North Greenland expedition 

 and for the special eclipse party at Point Loma, were thoroughly overhauled, 

 modified, repaired, and readjusted as necessary. The dip circles, theodolite, 

 sextant, and other jfield instruments for the MacMillan North Greenland 

 expedition were provided with celluloid caps for all parts that must be 

 handled with the fingers or which may touch the face during operations, 

 this having been indicated a desideratum through the experience both on 

 the Maud expedition of 1918 to 1921 and on the MacMillan Baffin Land ex- 

 pedition of 1921 to 1922. Desirable modifications and improvements indi- 

 cated by the laboratory tests of conductivity apparatus No. 7, both in the 

 instrument and its appurtenances, were made and corresponding parts pro- 

 vided for apparatuses Nos. 6 and 8. Improvements were made in the photo- 

 graphic equipment, including provision for increased lighting arrangements, 

 specially designed attachments, and facilities for enlargements and photo- 

 graphing of equipment, etc. Shop-lighting units were changed to increase 

 lighting efficiency. 



Miscellaneous. — The detailed drawings for field and observatory instru- 

 ments and for the various observatory buildings were maintained current 

 according to the structural and instrumental developments. 



The wireless equipment of the U. S. Navy type for wave-lengths 600 to 

 25,000 meters was tested and attachments for use in the field supplied before 

 shipping to Belize for the special work in Guatemala (see p. 238). Upon its 

 return it was thoroughly overhauled, retested, and supplied with appur- 

 tenances for its proper installation at the Huancayo Magnetic Observatory, 

 where it was shipped in October. The necessary instructions for field use 

 and for installation at the observatory were prepared by Messrs. Johnston 

 and Huff. A macadamized roadway from the main laboratory to the foundry 

 and storehouse was completed. 



MISCELLANEOUS ACTIVITIES. 

 American Geophysical Union. — Various reports and papers were prepared 

 and presented by members of the Department at the annual meeting of the 

 Union in Washington, April 17 to 19, 1923. The following members of staff 

 are among the officers of the Union : Louis A. Bauer, chairman of the Amer- 

 ican Geophysical Union and vice-chairman of the Section of Terrestrial 

 Magnetism and Electricity; J. P. Ault, chairman of the Section of Ocean- 

 ography. Mr. Fleming, as secretary of the Section of Terrestrial Magnetism 

 and Electricity, prepared, for publication by the National Research Council, 

 the reports and abstracts of papers presented before the meeting of that 

 section; also, as acting chairman of the committee on meetings, he had charge 

 of all arrangements for the annual meeting of the Union and its sections. 



