Geomagnetic Secular Variation during the Period from 1950 to 1955

The geomagnetic secular variation during the period from 1950 to 1955 is estimated on the basis of annual mean values of the geomagnetic field at some seventy magnetic observatories distributed all over the earth. Judging from the spherical harmonic analysis of the variation, it seems likely that the magnetic moment of the earth's dipole is still decreasing.