DEPARTMENT OF TERRESTRIAL MAGNETISM. 313 



the Earth's magnetic field is measured by electric means. Our 

 standard magnetometer has been compared at various times during 

 the past 15 years with magnetometers in use at most of the magnetic 

 observatories and in most of the magnetic services throughout the 

 world. The comparisons made between it and the sine galvanometer 

 have shown that the adopted standard for horizontal intensity may 

 be regarded as an absolute one well within theoretical and practical 

 requirements (see pp. 338 and 346). 



For an account of the atmospheric-electric work in the deck observa- 

 tory, see page 333 



Miscellaneous. — Various plans were prepared for the structural and 

 observational work at the observatories; requisite instruments were 

 also designed and constructed in the instrument shop. Considerable 

 time was devoted to the development of observatory buildings, instru- 

 ments, and equipment for standardized practice, particularly as pertains 

 to atmospheric-electric methods and records. (See pp. 333 and 337.) 



RESEARCH WORK IN WASHINGTON. 

 TERRESTRIAL MAGNETISISL 



The manuscript was completed for Volume IV of "Researches of the 

 Department of Terrestrial Magnetism," bearing the title ''Land 

 Magnetic Observations 1914-1920, and Special Reports" by L. A. 

 Bauer, J. A. Fleming, H. W. Fisk, W. J. Peters, and S. J. Barnett; this 

 volume is now passing through the press. The special reports are as 

 follows : 



Construction of Non-Magnetic Experiment Building of the Department of Terrestrial 



Magnetism, by J. A. Fleming. 

 Dip-Needle Errors Arising from Minute Pivot-Defects, by H. W. Fisk. 

 A Sine Galvanometer for Determining in Absolute Measure the Horizontal Intensity of 



the Earth's Magnetic Field, by S. J. Barnett. 

 Results of Comparisons of Magnetic Standards 1915-1921, by J. A. Fleming. 



When Volume IV has been issued, the observational data resulting 

 from our land magnetic surveys from 1905 to 1920 inclusive will have 

 appeared in print. The ocean magnetic data, 1905-1916, were pub- 

 lished in Volume III, and preliminary results for the period 1917-1921 

 have been pubHshed promptly in the various issues of the journal 

 Terrestrial Magnetism and Atmospheric Electricity. In addition and 

 upon request, magnetic-survey data, not already in print, were fur- 

 nished to interested institutions and investigators. 



Preparatory to the reduction to common epoch of the accumulated 

 data and the construction of new world magnetic charts, a variety of 

 investigations were undertaken; some of these have been completed 

 and others are in progress. Thus, for example, it is of importance to 

 have some idea at least, before making a new analysis of the Earth's 

 magnetic field, as to what extent the magnetic forces observed on the 

 Earth's surface may be caused, possibly, by a system of electric cur- 



