ON THE RELATION BETWEEN THE OLD AND THE NEW DEFINITION OF THE INTERNATIONAL METRE

Abstract

In October, 1960, the Eleventh General Conference of Weights and Measures adopted as the new definition of the International Metre, 1,650,763.73 wavelengths in vacuum of the unperturbed .606 μ line of Kr86. The present paper reports measurements, in terms of the new definition, on four copies of the metre which were well known in terms of the former International Metre prototype. They indicate no significant discontinuity in the metre, as a result of the transition to the new definition, and they demonstrate the accuracy to which the metre based on the old definition was realized in practice.