The Wealth of Nations_ Books 4-5 - Adam Smith [201]
PART III
Of the Expense of Public Works and Public Institutions
The third and last duty of the sovereign or commonwealth is that of erecting and maintaining those public institutions and those public works, which, though they may be in the highest degree advantageous to a great society, are, however, of such a nature that the profit could never repay the expense to any individual or small number of individuals, and which it therefore cannot be expected that any individual or small number of individuals should erect or maintain. The performance of this duty requires, too, very different degrees of expense in the different periods of society.
After the public institutions and public works necessary for the defence of the society, and for the administration of justice, both of which have already been mentioned, the other works and institutions of this kind are chiefly those for facilitating the commerce of the society, and those for promoting the instruction of the people. The institutions for instruction are of two kinds: those for the education of the youth, and those for the instruction of people of all ages. The consideration of the manner in which the expense of those different sorts of public works and institutions may be most properly defrayed will divide this third part of the present chapter into three different articles.
ARTICLE I
Of the Public Works and Institutions for facilitating the
Commerce of the Society
And, first, of those which are necessary for facilitating Commerce
in general
That the erection and maintenance of the public works which facilitate the commerce of any country, such as good roads, bridges, navigable canals, harbours, etc., must require very different degrees of expense in the different periods of society is evident without any proof. The expense of making and maintaining the public roads of any country must evidently increase with the annual produce of the land and labour of that country, or with the quantity and weight of the goods which it becomes necessary to fetch and carry upon those roads. The strength of a bridge must be suited to the number and weight of the carriages which are likely to pass over it. The depth and the supply of water for a navigable canal must be proportioned to the number and tonnage of the lighters which are likely to carry goods upon it; the extent of a harbour to the number of the shipping which are likely to take shelter in it.
It does not seem necessary that the expense of those public works should be defrayed from that public revenue, as it is commonly called, of which the collection and application is in most countries assigned to the executive power. The greater part of such public works may easily be so managed as to afford a particular revenue sufficient for defraying their own expense, without bringing any burden upon the general revenue of the society.
A highway, a bridge, a navigable canal, for example, may in most cases be both made and maintained by a small toll upon the carriages which make use of them: a harbour, by a moderate port-duty upon the tonnage of the shipping which load or unload in it. The coinage, another institution for facilitating commerce, in many