In an age when measuring devices of the highest precision are being produced, the bulk of quantitative information necessary to economic life is still determined by the less spectacular methods.The paper deals, mainly in retrospect, with the performance of Grid metering and mentions modifications which have been made as the result of operating experience over the past fifteen years. After a brief recapitulation of the commercial functions, comparative limits of error are discussed.The chief difference between Grid metering and other forms is the wide use of automatic summation and demand recording. A critical survey follows, of the various systems adopted, with a review of the difficulties encountered and the steps taken to overcome them. An account is given of the principles and methods of testing and maintenance.Changes in practice and design are described, with some remarks on the arrangements for recording performance and for summarizing meter readings for commercial and operational desiderata. Finally, a forecast is made of future developments.