An Act to explain and amend Two Acts, made in the Second, and Thirty ninth and Fortieth Years of the Reign of His present Majesty, for preventing the committing of Thests and Frauds by Persons navigating Bum Boats and other Boats, upon the River Thames, and for the more effectual Prevention of Depredations thereon, so far as relates to the Seizure of Exciseable Commodities.