History of magnetic measurements in Bohemia and long-term changes of ge.magnetic field components

Regular measurement of components of the Earth's magnetic field started in Klementinum in Prague in 1830 as the first on the European continent, and finished in 1926. Contemporary Czech geomagnetic observatories cover the period since 1952 till now. Together with the data from Niemegk it is possible to convert all values so that a coherent series 1830-2007 can be prepared. Magnetic declination increases during the whole period, the speed of the increase regularly varies with the period of about 74 years. The last minimum was observed in 1910, maximum in 1947. The intensity of the field in the horizontal component varies too with nearly the same period and nearly the same positions of maxima and minima