And whereas the building of villages and houses upon entailed estates may, in many cases, be beneficial to the publick, and might often be undertaken and executed, if heirs of entail were empowered to encourage the same by granting long leases of lands for the purpose of building: Be it therefore enacted by the authority aforesaid, that it shall be, and it is hereby declared to be, in the power of every proprietor of an entailed estate, to grant leases of land for the purpose of building, for any number of years not exceeding ninety-nine years.