To sustain an action for commissions, the broker must show direct employment by the principal or a direct authority for him to treat with the agents of the principal, and if the agency of a wife for her husband be relied upon, special authority or ratification must be shown. Harper v. Goodall, 10 Abb. N. Cas. (N. Y.) 161, 62 How. Pr. 288; Harrell v. Vieth, 13 N. Y. St. 738.