exemptions are not very numerous, are liable to some duties of customs. If any goods are imported not mentioned in the book of rates, they are taxed at 4s. 9 9/20d. for every twenty shillings value, according to the oath of the importer, that is, nearly at five subsidies, or five poundage duties.

The book of rates is extremely comprehensive, and enumerates a great variety of articles, many of them little used, and therefore not well known. It is upon this account frequently uncertain under what article a particular sort of goods ought to be classed, and consequently what duty they ought to pay. Mistakes with regard to this sometimes ruin the custom-house officer, and frequently occasion much trouble, expense, and vexation to the importer. In point of perspicuity, precision, and distinctness, therefore, the duties of