The time variations of the geomagnetic field at 10 European observatories were examined in detail. Fourier analyses were made for three field components at each of the observatories. Curves for each component were synthesized for three passbands: A low passband for periods greater than 30 years, a mid passband for periods equal to or less than 30 years but greater than 13 years, and a high passband for periods equal to or less than 13 years. The low passband results show only very smooth variations from which the linear prediction of secular variation, as is now in use, might give a good average result for 10--15 years if there were no other changes. The high passband results show the solar cycle effect that has been adequately treated before. The mid passband has an amplitude of tens of nT which changes differently at each observatory in such a way as to infer core sources. These time-varying anomalies are important to the understanding of secular variation.