The sketch of the situation during the geomagnetic storm at Greenwich on 4 February 1872. The circle with the dots in their centres indicate the position of the FAC flowing upward, the circles with crosses mark the FAC flowing downward. The boldness of the marks expresses the intensity of the electric currents. The dashed lines represent the lines of force of the magnetic field that is generated by the FACs. The ΔD sign stands for the deviation of the magnetic declination. Here we assume that the eastward electrojet flowed at lower magnetic latitudes than is the magnetic latitude of Greenwich.