If, during a vacancy in the office of the register of deeds, or his absence or inability to perform the duties of his office, there shall be no deputy register, or if such deputy be unable from any cause to perform the said duties, the judge of probate of the county may by writing under his hand, appoint some suitable person to perform the duties of register of deeds for the time being, who shall take an oath of office, and give such bond as the said judge shall direct and approve.