¶1— The matters in controversy on this appeal are between the plaintiff, who is a mechanic, and the appellant Dreste, who is the owner of a building in the city of St.. Louis. The defendant Doerste made a contract with Dreste to construct for him a brick dwelling-house to be erected on a lot belonging to Dreste. The plaintiff, as a subcontractor under Doerste, furnished the materials for, and did the brick work on, the building. Doerste failed to pay him, and in this action he sought a judgment against Doerste, and the enforcement of a mechanic’s lien against the building and the lot upon which it is situated. The petition is in form as for a quantum meruit, and is accompanied by an itemized account. The jury returned a verdict ■against Doerste for $782.20, with interest at six per ■cent, per annum from the seventeenth day of September, 1886, making the total sum of $959, for which judgment was entered against Doerste. The jury also found by their verdict that the plaintiff had perfected his mechanic’s lien against the building, and the court, in making the entry of judgment, provided for the enforcement of the lien against the building in satisfaction of the judgment, if Doerste failed to pay. brom that judgment Dreste alone has appealed.
¶2*136Wherever the common law is in force, it is the general rule that there can be but one suit for one cause of action. The appellant contends that this principle is applicable in this case,- and that under the evidence the action ought to abate. This is the appellant’s first assignment.
¶3To dispose .of this assignment we must first refer to the pleadings and the evidence upon which it is predicated. The defendant, Doerste, made no defense. Dreste filed an answer, in which he averred among other things that the house involved in this suit, and another belonging to him on an adjacent lot, were erected under one contract entered into between him and Doerste; that the plaintiff became a subcontractor under Doerste and agreed to do the brick work and furnish the necessary materials therefor, for both houses for the aggregate sum of $1,997; that all the work performed by him was done under this contract; that on the seventeenth day of September, 1886, the plaintiff instituted another'action in the circuit court of the city of St. Louis against the defendants to recover from Doerste the reasonable value of the work and materials for the other building; that, on the fifteenth day of April, 1890, he recovered a judgment in that action against Doerste for $1,283.75, and he also had a mechanic’s lien established against the building for that amount.
¶4The plaintiff ’ s reply put in issue the new matter contained in the answer.
¶5On the trial it was disclosed by the evidence that the work done by the plaintiff was performed under a parol contract between him and Doerste for both houses, in which the plaintiff agreed to furnish the brick and lay them in the walls for the gross sum of $1,997. Dreste’s counsel assumes in his brief that it was conceded that the houses were built under one general contract between Doerste and his client. This is denied by the respondent. The plans and specifications are for *137two houses, but we find nothing in the evidence tending to show that there was but one contract. For aught that appears there were two contracts, one for each building. The defendant read in evidence the pleadings and judgment entry in the former action, by which it appeared that that suit and this were instituted at the same time. Doerste made default, and the defendant Dreste filed an answer containing a general denial. The proceeding resulted in a judgment a few months prior to the trial of the present action. It is believed that the foregoing statement will be sufficient for a proper understanding of the legal questions under consideration.
¶6There are two questions involved in this inquiry:
¶7First. Whether the rule against the splitting of demands is applicable to mechanic’s lien cases, where the work has been performed by a subcontractor in the construction of two or more buildings situated on contiguous lots ? Second. If the rule applies, is such a defense available to Dreste in this action ?
¶8Under our mechanic’s lien law, as it stood prior to 1877, the first question would under any view have to be answered in the negative. In 1877 the legislature amended the law by adding the following section, designated in the revision of 1889 as section 6729: “ When the improvement consists of two or more buildings united together and erected on the same lot or contiguous lots, or upon separate buildings upon con* tiguous lots, and erected under one general contract, it shall not be necessary to file a separate lien upon each building for the work done or materials furnished in the erection of such improvements.”
¶9The defendant’s contention is that the section must be construed as mandatory in its requirements, and that, where the facts justify its application, but one lien can be filed, — whether the lienor be an original contractor or not. Hence the argument is made that in *138such a case no valid reason can exist against the application of the law, prohibiting the splitting of demands either for suit or for sale or assignment.
¶10We are of the opinion that the defendant’s argument in support of this question is unsound, because it is based on a false, premise. We do not think that the statute is mandatory in its requirements. If it be conceded that there was but one general contract with Dreste for the construction of the houses, the plaintiff might have filed but one lien on both houses, but there was nothing compulsory about it. The legislature intended by the amendment to the law to extend rather than restrict the rights of mechanics and materialmen in filing liens. The object was to afford the contractor or subcontractor the privilege of filing only one lien, if he was satisfied that there was nothing in the way of its enforcement against the entire property. But a case could be readily imagined where it would be impracticable to enforce one lien for work done and materials furnished for two or more houses situated on separate lots. Some third party might have a like lien on only one of the houses, or there might be a mortgage on one of the lots, or different mortgages might exist in favor of different parties against each lot separately. Such conditions or complications might affect materially the enforcement of one general lien. Hence, we conclude that the legislature intended, in such a case, to leave it optional with the contractor or subcontractor to file one or more liens. If separate liens are filed the owner might have the right, where third parties are in nowise interested, to have the actions consolidated under section 2189 of the Revised Statutes of 1889, and thus save the costs of defending two actions. When this view of the statute is considered, it must be admitted that the law against the splitting of demands cannot be made to apply to actions for the enforcement of ¡mechanics’ liens against houses situated on separate lots.
¶11*139Our conclusion on the first proposition makes it unnecessary for us to decide whether the defense touching the splitting of demands could be made by Dreste, or whether it was available only to the original contractor. This assignment will be ruled against the defendant.
¶12It is next insisted that the lien charge is in excess of what the plaintiff was entitled to recover. It is no objection to the maintenance of a suit like this that there was a special contract for the work. The mechanic is at liberty to abandon the contract and sue for the reasonable value of the work ; but his recovery in such a case, for the work embraced in the contract, must not exceed his contract price. Jodd v. Duncan, 9 Mo. App. 417. Now in the first action the judgment was for $1,102.64; in this the recovery was for $782.20 ; the plaintiff admitted that he had been paid on account of the building $298, making a total of $2,182.84. This amount is in excess of the contract price in the sum of $185.84. If the entire work performed by the plaintiff had been included in the contract, then the defendant’s assignment would be well taken. This, however, is not the-case. The plaintiff’s evidence tended to show that the contract was changed in several particulars, and that in consequence of such changes he had to do extra work and furnished additional materials; and that the value of the additional work and materials was $400. This assignment will be likewise overruled.
¶13It is next claimed by defendant that there was no competent proof concerning the service of the notice of the lien. The only evidence of service was the return of the sheriff indorsed on the notice. The service was had in 1886, and the contention is that, under the law as it then stood (R. S. 1879, sec. 3190), the fact of service could not be established by the return of the officer. On the other hand the plaintiff claims that, as the case was tried after the revision of 1889 took effect, the sufficiency of this proof must be determined by the law *140in force at the date of the trial. In 1889 the legislature amended section 3190 by adding thereto the following : “Such notice may be served by any officer authorized by law to serve process in civil actions, or by any person who would be a competent witness. When served by an officer, his official return indorsed thereon shall be proof thereof, and when served by any other person the fact of such service shall be verified by affidavit of the person so serving.” The amendment only pertained to the remedy, and its enactment imposed no new obligation or duty on the. defendant, nor did it take away any vested right acquired by him under existing laws. We can, therefore, conceive of no valid reason why this new rule of evidence should not apply in this case. This assignment will also be overruled.
¶14At the plaintiff’s instance, the court gave the foling instruction : “The court instructs the jury that, if they find for plaintiff, they will assess the damages against defendant Doerste at such sum as they may find plaintiff is entitled to recover, together with interest from September 17, 1886, at the rate of six per cent, per annum.”
¶15This instruction is fatally defective. It left the jury free to determine the standard of value according to the notions of each individual juror. It is admitted that the plaintiff agreed to do the brick work and furnish all necessary materials for both houses for the gross sum of $1,997. It was also conceded that he had already recovered a judgment for $1,102.64 on account of work done under this contract, and that he had been paid the additional sum of $298, leaving a balance under the original contract of $596.36. Hence, the jury should have been instructed that, if the work done by the plaintiff was covered by this original contract, he could only recover its reasonable value, as shown by the evidence, not to exceed the sum of $596.36 ; but that, if the plaintiff did extra work, or furnished materials outside of the contract, *141then the reasonable value of such extra work and additional materials, as shown by the evidence, ought to be added. While it may be true, as we have shown, that the verdict of the jury finds support in the evidence, yet it is impossible for us to say that the result was reached by the application of the proper rules governing the plaintiff’s right of recovery. The measure of damages in all cases is a question of law, and, if the court undertakes to instruct the jury on the question, it must do so properly and fully. Shenuit v. Brueggestradt, 8 Mo. App. 47; Matney v. Gregg, 19 Mo. App. 107 ; Morrison v. Yancey, 23 Mo. App. 670; Williams v. Iron Co., 30 Mo. App. 662; Flynt v. Railroad, 38 Mo. App. 94; Wilburn v. Railroad, 36 Mo. App. 203. In this case tbe jurors were left to decide the case according to their own fancy, without any restrictions or limitations whatever.
¶16For the error in this instruction, the judgment will be reversed and the cause remanded.