The Wealth of Nations by Part 5 Chapter 2 Page 138

to about twenty-seven pounds ten shillings of our money. If the stamp is of an inferior price to what the testator ought to have made use of, his succession is confiscated. This is over and above all their other taxes on succession. Except bills of exchange, and some other mercantile bills, all other deeds, bonds, and contracts are subject to a stamp-duty. This duty, however, does not rise in proportion to the value of the subject. All sales of land and of houses, and all mortgages upon either, must be registered, and, upon registration, pay a duty to the state of two and a half per cent upon the amount of the price or of the mortgage.

This duty is extended to the sale of all ships and vessels of more than two tons burden, whether decked or undecked. These, it seems, are considered as a sort of houses upon the water.