Tables 732-734 

 TERRESTRIAL MAGNETISM 



579 



APPROXIMATE VALUES FOR ANNUAL RATES OF SECULAR CHANGE IN THE MAGNETIC 

 ELEMENTS DECLINATION (D), INCLINATION (/), AND HORIZONTAL INTENSITY (H) 



FOR THE EPOCH 1 925 1 



(Because of the different intervals covered by available data and the known large accelerations in some 

 )arts, the values given for the annual secular-changes at intersections of parallels and meridians indicated 

 ire approximate except for those localities near magnetic observatories; in some cases there is great un- 

 :ertainty and the values for these are enclosed in parentheses. The signs of the values given are in the 

 ilgebraic sense for extrapolation considering east declination, north inclination, and horizontal intensity 

 is positive and west declination and south inclination as negative. 



1 Prepared by H. W. Fisk, of the Department of Terrestrial Magnetism, Carnegie Institution of Washington. 

 mithsonian Tables 



