52 ECONOMIC PRINCIPLES

cover prime costs and supplemental costs together, and
represent the proportion of total expenses to total output.
If we could suppose it possible to utilise to the full, at all
times, the appliances provided, we might expect the point of
maximum economy to be the point, the cost of production
corresponding to which would measure the price at which the
goods could profitably be supplied. But it is only at busy
times that the applicances are fully utilised, and at ordinary
or dull times they are often more than sufficient to permit of
realising the greatest possible economy. Hence, in practice,
at ordinary times some part of the productive apparatus lies
more or less idle, the point of maximum economy is not
reached, and the costs which measure the price at which representative
 producers can place the goods on the market
are not marginal costs of production. It is possible to look
at the case from the point of view of a period of production
long enough to include both busy and dull times, and to
treat rather of the maximum economy, of utilisation of appliances,
 practically possible than of the maximum economy
technically possible, The costs which condition supply are
then somewhat greater than those corresponding to the
highest technical efficiency of the appliances of the representative
 establishment, except when those appliances are
being used to the fullest extent. Generally, therefore, these
costs will not be marginal costs.
We see, then, that where the supply of commodities is
regularly organised for a market of reasonable steadiness,
that supply is enlarged or restricted in accordance with
expectations of profit, which expectations are based on a
consideration of expenses on one side, and the prospect of
realisation of a value sufficient to cover them with a profit
on the other. In a case of such steady supply, it is possible
to estimate the value anticipated by a consideration of the
expenses undertaken. Such a measure has a concrete reality
about it which does not belong to the estimate of the
marginal utility, though this likewise may serve as the
measure of value. It is not to be wondered at, therefore,
that these expenses or, as it is commonly said, the cost of
production, has been made to serve as the gauge of the