Abstract
As reported in the preceeding chapter, the absolute accuracy of the G. S. I. Standard Magnetometer depends mainly on the coil-constant of the primary standard coil and the values of the electrical standards (standard cells and standard resistances). Of these, the coil is specific to the standard magnetometer. This chapter therefore deals with the methods of producing precisely completed coil bobbin and copper wires of uniform diameter and cross section and the process of constructing the Helmholtz-Gaugain standard coil. This paper also reports the methods of fine measurements of coil dimensions (radius, distance, pitch and number of turns of the two windings of the coil) in the accuracies of better than 0.5X10-5 in order to secure the composite accuracy of 1X10-5 in the coil-constant.
