The absolute value of a current has been measured by the current balance, using improved coils. The previous work had shown that improvements in the coils were required in order to make them fulfill more nellrly the conditions assumed in developing the equations for computing the absolute value of a current from the force measured by the current balance. These new coils consisted of one moving coil made in the form of a short solenoid and one moving coil and one pair of fixed coils wound from anodized aluminum ribbon in the form of a flat spiral.The results obtained with various combinations of these new coils and one pair of the old fixed coils are consistent among themselves, and their weighted average can be expressed as 1 NBS international ampere=O.999 86 absolute ampere.This result differs appreciably from that obtained in the preceding work, but it is felt that this new value is more reliable because of the improved coils which were used and the greater consistency of the results. CONTENTS Page

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The value of an electric current has been measured in absolute units by a current balance, and simultaneously in international units by standard cells and standard resistors. In the current balance a subdivided helix served as the two fixed coils and, as the moving coil, either a short helix or a compact spiral. The two moving coils were the same ones that were described in a previous paper in which the fixed coils were spirals.The value obtained when using these two moving coils and the subdivided helix differs by only 4 parts in a million from the value obtained when using these moving coils and spirally wound fixed coils. These values are, however, somewhat different from those obtained when using multilayer coils wound with copper wire. The relationship between the absolute and International ampere, from the most dependable measurements at the National Bureau of Standards, may be expressed as 1 NBS International ampere = 0.999 850 absolute ampere.

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