332 CARNEGIE INSTITUTION OF WASHINGTON. 



DETAILS OF INVESTIGATIONAL AND EXPERIMENTAL WORK. 



DIVISION OF RESEARCH !N TERRESTRIAL MAGNETISM AND ELECTRICITY. 



This division has continued under the immediate charge of the 

 Director and its work consists of investigations bearing upon the 

 phenomena and causes of the Earth's magnetic field and of its electric 

 field and of their variations (secular, annual, diurnal, and spasmodic). 



Magnetic observations during solar eclipse of May 29, 1919. — Some 

 further progress was made with the analysis of the magnetic effects 

 observed during the solar eclipse of May 29, 1919. The analysis 

 could not be wholly completed, pending the receipt of additional data 

 from cooperating observatories. A first summary of results was 

 published in full in the September 1920 issue of Terrestrial Magnetism 

 and Atmospheric Electricity, and an abstract was given in the annual 

 report of last year. It is hoped that a second summary may soon be 

 published. 



Volume IV oj Researches of Department of Terrestrial Magnetism. — 

 Various assistance was rendered by members of the division in the 

 preparation of the manuscripts of this volume. 



Vertical electric currents and the relations between terrestrial magnet- 

 ism and electricity. — A brief statement of the bearing of this problem 

 upon the theory and composition of the Earth's magnetic and electric 

 fields will be found on page 314. Preliminary results of the computa- 

 tions were published in Terrestrial Magnetism and Atmospheric 

 Electricity for December 1920 (see abstract on pages 347-348). 



Magnetic and allied effects, May 13-16, 1921. — The striking geo- 

 physical effects which accompanied the remarkable sun-spot activity 

 during the middle of May 1921 were briefly described on pages 307 

 and 309. In view of the general interest shown, data are being col- 

 lected from various sources and an analysis is to be undertaken. 



Measures of the electric and magnetic activity of the Sun and the Earth, 

 and interrelations. — Various results of this comprehensive investigation 

 have been presented before the April meeting of the section of Terres- 

 trial Magnetism and Electricity of the American Geophysical Union, 

 the general meeting of the American Philosophical Society at Phila- 

 delphia in April, and before the Philosophical Society of Washington 

 in May. The paper as published in the March-June issue of Terrestrial 

 Magnetism and Atmospheric Electricity comprises the following 

 topics: I: General considerations and remarks; II: Measure of the Sun's 

 activity; III: Measure of the Earth's magnetic activity; IV: Relations 

 between solar activity and the Earth's magnetic and electric activity 

 (see abstract on pages 348-351). A second paper is in preparation. 



New measures of solar activity and the "Earth-effect."- — Brief reference 

 was made to this investigation on page 309, A paper was presented 

 before the Astronomical Society in August (see abstract on pages 

 350-351). 



