Abstract :
Summary form only given. The General Conference of Weights and Measures (CGPM) is the organisation which has the ultimate responsibility for the seven components of the International System of Units (SI). CGPM has authorised the revised values for the volt and the ohm to be discussed at the Colloquium. A brief survey is given tracing the origins and development of the basic electrical and mechanical units in order to identify the changes, in principle and practice, which have occurred up to 1989. The values of the maintained reference standards, as preserved by various national standards laboratories, are discussed
