The plaintiff furnished Vandenburgh & Qui ruby, who were partners, lumber which was used by them in the construction of two houses which they had'contracted to build, one for the defendant, and one for one “Edmans, at the contract price of about $5,900 each, and, being in impecunious circumstances, contracted with the plaintiffs to furnish lumber and material on credit, and to secure the plaintiff for such credit assigned to the *312plaintiffs the contract with the defendant, as collateral to the payment of all moneys due or to grow due from such builders to the plaintiff.
On the day of making such assignment, the plaintiffs gave notice to the defendant of such assignment.
The lumber was delivered by the plaintiffs, and at the time of the delivery of the same the plaintiffs charged the lumber used by Quimby & Vandenburgh in the Edmans house to Julia A. Ed-mans. After the notice of the assignment of the Snyder contract to the plaintiffs, Snyder paid to plaintiffs at different times sums amounting in the aggregate to the sum of one thousand dollars, and thereby recognized the validity of the assignment, and his obligation to pay the plaintiffs for some^of the material at least furnished by plaintiffs to Vandenburgh & Quimby, which went into the construction of this house, to the extent of his liability to the builders, had not the assignment been made to the plaintiffs.
In Spicer and Thomas v. Snyder, 34 St. Rep., 376, this court held that the assignment from Quimby & Vandenburgh to this plaintiff did not vest in the assignee absolute right to all the money contracted by. the defendant to be paid on this contract, but merely an equitable interest, operating upon the indebtedness as it arose from time to time, and that money paid by the defendant in the construction of this house to mechanics and material men was payment on and satisfied the contract to the extent of such payment.
Payments of that character became a proper subject of inquiry on this trial, and within that decision the plaintiffs could only recover, as assignées, the balance due upon the contract, after deducting all payments made by the defendant to other material men for material furnished in the construction of this house.
As the evidence stood in that case, this court held that the plaintiff was entitled to recover a balance of $372.68, the amount due upon the contract estimated upon the above basis. How much the evidence on this trial would change that amount it is not important for us to consider, as this court, as the case now stands, could in no event order a judgment if a balance were found due upon the contract.
But we think that on this trial the court erred in receiving evidence directed to the question of payments by and liabilities of the defendant for materials furnished by persons not parties to this contract, which might have influenced the verdict of the jury, for which this judgment should be reversed.
The question put to Vandenburgh, which appears on page 145 of the case, in these words : “ Q. Will you state what other bills there are outstanding for lumber and materials against the Snyder house for which the defendant Snyder is liable? ” This was properly objected to, and, we think, improperly received.
The answer clearly involved a conclusion of the witness as to the legal question of the defendant’s liability and, also, the determination of facts out of which that legal question arose. It placed the witness in the position of the court and jury for the determination of conclusions of law and fact, and the answers *313which followed were not statements of facts, but many of them conclusions of the witness.
As this was one of the vital questions in the case, this court cannot assume that this illegal evidence was harmless.
There were other questions raised by the plaintiff upon the admissibility of evidence somewhat similar to the one above discussed ; but it is unnecessary for us to discuss them here. Upon the whole case we are of opinion that the' motion made by the plaintiff to set aside the verdict and for a new trial upon the minutes should have been granted.
The evidence as it stands shows a substantial performance _ of the contract in all essential particulars, except such as to which there was an actual or implied waiver by the defendant.
The assignment of the builder’s right was, therefore, entitled to payment of the contract price less the advancement made to him or to others for material furnished in the construction of the house.
The burden of showing such payment was a part of his affirmative defense and we think he has failed in establishing that affirmative proposition.
The judgment should be reversed and a new trial ordered, costs to abide the event.
Putnam and Herrick, JJ, concur.