That any letter of attorney or other instrument containing a power to convey lands, as agent or attorney for the owners of such lands, executed and acknowledged in the manner provided by the statutes of this state for the execution and acknowledgment of deeds or other conveyances of land, and which shall have been actually recorded in the office of the register of deeds in any county in the state prior to the first day of March in the year 1847, may be proved in any court by the production of such record or a duly certified copy thereof and such record or a duly certified copy, shall be prima facie evidence of the due execution and acknowledgment of such letter of attorney or other instrument.