428 



TABLE 570. 

 TERRESTRIAL MAGNETISM. 



Secular Change of Declination. 



Changes in the magnetic declination between 1810, the date of the earliest available observations, and 1920. Based 

 on tables in "Distribution of the Magnetic Declination in Alaska and Adjacent Regions in 1910" and "Distribution 

 of the Magnetic Declination in tin- United States for January i, 1915," published by the United States Coast and 

 Geodetic Survey. For a somewhat different set of stations, see 6th Revised Edition of the Smithsonian Physical Tables. 



SMITHSONIAN TABLES. 



