In an action for a broker's commissions, the court's charge, that if the purchasers went to South Dakota, by reason of plaintiff's introduction to defendant, and examined the lands defendant had for sale, and if defendant participated in the business resulting in sales, then the sales were made by defendant within his contract to pay to plaintiff, was a sufficiently definite instruction on the issue, of the manner in which defendant must have sold the land in order to render himself liable. Murphy v. Hiltbridle, 132 Iowa, 114, 109 N. W. 471.