DEPARTMENT OF TERRESTRIAL MAGNETISM. 285 



Investigational work of Research Associate Slocum, — Dr. Frederick 

 Slocum, appointed Research Associate in the Department for the 

 period of June 16 to September 15, investigated the following matters 

 (see pp. 299-301): 



1. Rigorous methods of computation of terrestrial-refraction corrections. 



2. Methods and observations for dip-of-horizon made on the Carnegie and 

 relation of the results to temperature differences of air and water, length and 

 height of waves, angle at which the vessel cuts the waves, barometric pressure, 

 and geographic region. 



3. Dynamic deviations, tilting error of compass, expression for acceleration 

 of a table subject to a crank-and-piston motion, and equations of motion of a 

 compass needle on a table subject to a simple harmonic motion. 



Building work. — On page 283 reference has already been made to 

 the building work at Washington (Experiment Building). (See also 

 p. 305.) 



International Section of Terrestrial Magnetism and Electricity. — A 

 sufficient number of countries having formally signified their adhesion 

 to the International Geodetic and Geophysical Union, as well as having 

 made pa,yment of their respective contributions, this section may now 

 be regarded as definitely established. The duties devolving upon the 

 Director as secretary of the International Section and director of its 

 central bureau have received attention from time to time. 



American Section of Terrestrial Magnetism and Electricity. — This 

 section of the American Geophysical Union was definitely organized in 

 April 1920, for the purpose of assisting in carrying out the purposes of 

 the International Section of Terrestrial Magnetism and Electricity, in 

 particular as regards the furtherance of investigational woik in the 

 United States of national and international scope. The present officers 

 are: Louis A. Bauer, chairman (also vice-chairman of the American 

 Geophysical Union); W. F. G. Swann, vice-chairman; J. A. Fleming, 

 secretary. 



Lectures on the solar eclipse of May 29, 1919, and related phenomena 

 were given at a number of universities by the Director, who had 

 observed the total solar eclipse of May 29, 1919, under very favorable 

 conditions, at Cape Palmas, Liberia, where totality lasted the excep- 

 tional length of 6 minutes 33 seconds. Papers on the results of the 

 geophysical observations were also presented by him before various 

 academies and societies. 



National Research Council. — Various duties have been performed by 

 Messrs. Barnett, Bauer, Fleming, Mauchly, and Peters as members of 

 committees of the council. 



