Abstract :
The conventional methods of providing for the depreciation of engineering plant are criticized on the grounds that they contain arbitrary features, and a general theory is formulated which is not subject to such criticism. The general theory is applied first to individual projects, showing how the factors which affect depreciation operate, and secondly to an integrated industry, showing how the programmes for writing off the investments in the industry can be co-ordinated and the economic assessment of new projects facilitated in consequence. The effects of variations in the value of money are also considered. The propositions are illustrated by numerical examples drawn, in the case of the application to an integrated industry, from the field of public electricity supply.
