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