Proton vector magnetometer

Z and H, as well as F, have been measured at the Fredericksburg Magnetic Observatory with a proton vector magnetometer, combining a proton-precession intensity magnetometer and a Helmholtz coil system mounted on a horizontal circle. Formulas for the effect of various instrumental adjustments are given without proof; the only critical adjustment is the level of the horizontal circle (magnetometer base). The internal consistency of the observed values ZP, FP, and HP is indicated by the smallness of computed values HP - (FP2 - ZP2)½; these values are less than 3 γ in magnitude and have a mean of 0.4 γ. Preliminary results of comparisons with the observatory sine galvanometer and earth inductor are: The source of the H difference is now being investigated.