LAND MAGNETIC OBSERVATIONS, 1914-1920. 



INTRODUCTION. 



This publication is the fourth of the series by the Department of Terrestrial 

 Magnetism of the Carnegie Institution of Washington, bearing the general title 

 "Researches of the Department of Terrestrial Magnetism." Each volume has a 

 subtitle setting forth briefly its special contents. Thus the first volume, desig- 

 nated as Volume I and entitled "Land Magnetic Observations, 1905-1910," con- 

 tains the results of all magnetic observations made on land by the Department 

 from the beginning of its observational work in February 1905 to the end of 

 December 1910. Volume II, "Land Magnetic Observations, 1911-1913, and 

 Reports on Special Researches," contains the results of all magnetic observations 

 made on land during the three years, January 1, 1911, to December 31, 1913. 

 The titles of the special reports in that volume are: Research Buildings of Depart- 

 ment of Terrestrial Magnetism, by L. A. Bauer and J. A. Fleming; Magnetic 

 Inspection Trip and Observations during Total Solar Eclipse of April 28, 1911, 

 at Manua, Samoa, by L. A. Bauer; Results of Comparisons of Magnetic Standards, 

 1905-1914, by L. A. Bauer and J. A. Fleming. Volume III, on "Ocean Magnetic 

 Observations, 1905-1916, and Reports on Special Researches," contains the final 

 results of the ocean magnetic observations made aboard the Galilee in the Pacific- 

 Ocean, 1905-1908, and aboard the Carnegie in the Atlantic, Indian, and Pacific 

 Oceans, 1909-1914, together with preliminary results of the observations on the 

 1915-1916 portion of the Carnegie's cruise IV. The special reports of Volume III 

 are as follows: Results of Atmospheric Electric Observations made aboard the 

 Galilee (1907-1908), and the Carnegie (1909-1916), by L. A. Bauer and W. F. G. 

 Swann; Some Discussions of the Ocean Magnetic Work, by L. A. Bauer and 

 W. J. Peters. 



The final reduction of the land magnetic observations given in the present 

 volume (IV) was delayed by the Great War, both because of lack of computa- 

 tional assistance and the difficulty encountered in promptly obtaining required 

 data from cooperating observatories and countries. In order to meet the demand 

 from establishments engaged in the preparation of magnetic charts and geographic 

 maps, preliminary magnetic and geographic data were supplied in manuscript 

 according to requests received; thus immediate needs in advance of final publi- 

 cation were promptly met. 



A future volume, in preparation, will be entitled "Ocean Magnetic Observa- 

 tions, 1915-1921, and Special Reports." The final reduction of the ocean mag- 

 netic observations was delayed for the same reasons as given for Volume IV. 

 Preliminary results have been published promptly in the various issues of "Ter- 

 restrial Magnetism and Atmospheric Electricity," and in this manner, or by 

 manuscript copies, hydrographic establishments have been kept informed of the 

 data required for new, or revised, issues of magnetic charts. 



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