If the residence of the president of the lessor company is unknown to the plaintiff and his attorney, an affidavit showing the fact, filed with the Secretary of State, together with the petition, shall be sufficient, instead of the notice to the president required in Code Section 46-8-312, provided that the plaintiff shall not be compelled to bring an action against any such lessor and give the notice as provided in this Code section, but may do so at his option; but when such notice is given to the lessor, the judgment rendered in said action shall be as binding upon the lessor as though service had been made as provided by law for service upon railroad companies.