delivered the opinion of the court.
4. Contracts, § 177*—how construed. In an action to recover on an ambiguous written contract, where the construction contended for by plaintiff was that defendant was bound to have each of its wagons repainted by plaintiff at least once a year during the term, at a price stipulated in the contract, contract construed and held to show an intention that each vehicle named should undergo a general overhauling and repainting by plaintiff each year during the life of the contract, such intention being inferred from the use of the words “throughout the year” and “one year” used in the contract. 5. Evidence, § 351*—when parol evidence admissible to aid in construction of written contract. "In an action on an ambiguous written contract, held not error to admit evidence of correspondence and conversations between representatives of the parties, either occurring at the time the contract was made, or during its performance, for the reason that such evidence, if it tends to show what construction the parties themselves placed thereon, is always admissible in aid of its construction, the rule being that where it appears that parties have given to the instrument a particular construction by acting upon it in a particular way, the court will usually adopt such construction. 6. Witnesses, § 194*—when use of memorandum allowed. In an action to recover on a written contract, held not error to allow a witness to refresh his recollection by consulting a memorandum. 7. Witnesses, § 185*—when answer not responsive. Where a witness is called to testify as to market prices for painting a certain sort of wagons, held not error to strike out his testimony where it appears that his testimony is of the prices which he charged in his own business for such work, and not of the market price. 8. Interest, § 19*—when improper to allow. In an action to recover on a written contract for repairing and repainting wagons, a judgment of $2,431.10 for plaintiff, which included interest on all items for which plaintiff recovered, held excessive to the extent of $331.17, for the reason that interest to that extent was improperly allowed, plaintiff’s damages, except as to one item which was admitted, being not sufficiently certain to enable defendant to know, prior to verdict, what it owed, and hence the statute as to interest was inapplicable.