Provided always, that all leases made or to be granted under the authority of this Act, shall be made or granted for a rent not under the rent payable by the last lease or sett, and without grassum fine or foregift, or any benefit whatsoever, directly or indirectly, reserved or accruing to the granter, except the rent payable by the lease; and that no such lease shall be granted till after the end or other determination of any former lease of the same premises, or that such lease, if granted for a time certain, shall be within one year of being determined, and that all leases otherwise granted shall be void and null.