A contract of employment may be so drawn as to deprive the broker of the right to a commission, if the transaction should fall through because of a defect in the principal's title. Louisville, etc. R. Co. v. Shepard, 126 Ala. 416, 28 S. 202; Clark v. Hovey, 105 N, E. 222, 217 Mass. 485; Chas. Somers Co. v. Fix, 134 P. 932, 75 Wash. 233; Slade & Bassett v. Crum, 193 S. W. 723, - Tex. Civ. App. -; Genatt v. Robinson, 165 N. Y. Sup. 464.