Where the Money to be paid as the Consideration for any such Grant, Conveyance, or Assurance, shall not exceed the Sum of ten Pounds, such Grants, Conveyances, and Assurances, under the Seal of the said Duchy, shall be subject to no Stamp-duty for the same; and where the Consideration Money to be paid shall exceed ten Pounds, that the said Grants, Conveyances, and Assurances, shall be subject only to such Stamp-duty as is or are, or hereafter may be by Law requisite for any Deeds, whereby Lands, Tenements, or Hereditaments, are conveyed.