Photo of a page of KNMI’s 1859 yearbook displaying the geomagnetic measurements made in Utrecht in September. The last three major columns left from the remarks section denote the declination, inclination and horizontal intensity measurements. For each component there are three sub-columns of which the central sub-column lists the observed value at 14:00 in ‘schaaldelen’ (scale parts). The left and right sub-columns list the differences between the 14:00 values and the morning and evening values respectively.