DEPARTMENT OF TERRESTRIAL MAGNETISM. 281 



native of Lima, who secured his collegiate training at SjTacuse Uni- 

 versity, New York. Furthermore, A. Smith, carpenter, was sent to 

 Peru in June to assist Dr. Edmonds. 



Washington. — The atmospheric-electric work at Washington was 

 conducted throughout the year under the charge of Dr. S. J. Mauchly, 

 in the small house erected on the deck of the laboratory. 



Comparisons of magnetic instruments have been made from time to 

 time at the Standardizing Magnetic Observatory at Washington, as 

 well as at various foreign observatories. For details regarding the 

 Observatory work, see pages 291-293. 



RESEARCH WORK IN WASHINGTON. 

 TERRESTRIAL MAGNETISM. 



The return to normal activities has made possible further progress 

 with the manuscript for Volume IV of the Researches of the Depart- 

 ment. This volume will contain the results of the land magnetic obser- 

 vations, 1914 to 1919, those of the ocean observations 1917 and 1918, 

 besides monographs on special subjects. It is hoped now that the 

 manuscript will be completed by the end of 1919. 



The extensive observations made in connection with the total solar 

 eclipse of June 8, 1918, by the Department and by many cooperating 

 observatories, were reduced and discussed and published in final form 

 in the issues of Terrestrial Magnetism and Atmospheric Electricity for 

 September and December 1918, and March and June 1919. The results 

 will be found summarized on pages 306-308. It is beheved that the 

 gratifying cooperation received and the prompt transmission of data, 

 both with regard to this eclipse and the recent one of May 29, 1919, is 

 to be attributed in some measure, at least, to the prompt reduction and 

 publication of data. 



In connection with various problems, the Director has had occasion 

 to establish, in a form convenient for ready calculation, formulae for the 

 potential and field components of certain uniformly magnetized bodies, 

 such as solid ellipsoids of revolution and elliptic homoeoids. (See 

 abstract, p. 308.) 



Various theoretical investigations connected with miUtary matters 

 were brought to a conclusion and may be reported upon at some future 

 time. 



Improvements in reduction-methods of field observations have been 

 made by Mr. Fisk, as shown in the abstract, page 313. 



The design of a sine galvanometer for measuring the field intensity of 

 the Earth's magnetism with great precision and rapidity has received 

 further improvement at the hands of Dr. Barnett, and the construction 

 in the Department's shop has been begun. For improvements in other 

 instrumental matters, see pages 299-301. 



