TERRESTRIAL MAGNETISM. 



TABLE 126. 



Secular Variation of Declination in the Form of a Function of the Time for a Number of Stations. 



More extended tables will be found in App. 7 of the United States Coast and Geodetic Survey Report for 1888, from 

 which this table has been compiled. The variable m is reckoned from the epoch 1850 and thus t 1850. 



* Approximate expression. t East longitude. 



t Compiled from a series of observations extending back to 1541. The primary wave follows the sum of the con- 

 stant and first periodic term closely. The period seems to be about 470 years. In the expression for the secondary 

 wave n = t 1700. 



SMITHSONIAN TABLES. 



