272 ECONOMIC PRINCIPLES

purely at securing the greatest money surplus of income
over expenditure: the public monopoly may be administered
either with this same end, or with the end of yielding its
advantage partly in the provision of a supply on cheaper
terms, and only partly, if at all, in the net income yielded
by the enterprise. It is maintained by some that the price
should be arranged so that the profit, over and above the
interest on borrowed capital, should be maintained at a
figure closely approximating to zero. It is to be observed
that the whole community, in such a case, takes the risks of
loss associated with the enterprise, while, when this last
policy is followed, only those members of the community
who consume the product in question share in the advantages
of the enterprise. If the policy sometimes advocated, of
providing, by public enterprise, commodities like tramway
services at prices below their cost, be followed, there is
afforded a more extreme instance of placing the burden of
cost on one body of individuals, and giving the advantages
purchased to another body. The latter body only comprises
a part of the former, and may include many who do not
share in the risk and expense.
When we turn to other classes of public services, other
principles of sharing the expense may be adopted. In such
a case as street cleansing and lighting, it might be argued
that the sharing of expenses should be in the same proportion
 as in the case of requiring each householder to do
his own share of the work, or to cause it to be done. The
street area immediately adjoining the property owned or
occupied by any citizen (we do not stay here to inquire
whether ownership or occupancy should be the test) would
then form the measure of the charge imposed on that
citizen in respect of such services.
But the interests of each in matters of this kind are not
wholly gauged by such a measure. In the case of watersupply,
 for example, it is, for some purposes, desirable to
impose a charge of the nature of an ordinary price for the
supply. But the community is also concerned to secure
that an adequate supply of water shall be given to, and used
by, its poorer members. The charge by quantity used may