This is an action to recover the amount awarded to the plaintiffs as damages for laying out Peterborough Street in Boston, and the interest on the award from December 2,1896, the date when the defendant entered on the plaintiffs’ land to construct the street. Before the adoption of the order by the board of street commissioners, the plaintiffs and others signed and delivered a writing, like that which appears in Aspinwall v. Boston, 191 Mass. 441, 444, and in Averill v. Boston, 193 Mass. 488, 491.
The board of street commissioners laid out the street and the city constructed it within a reasonable time, in accordance with the terms of this writing, but no assessment of betterments was made until after the commencement of the present action. Soon after the action was begun, betterments were assessed, under St. 1902, c. 527, and the assessment upon the plaintiffs, about the legality of which no question is made, exceeds the amount of the damages which they seek to recover. The question is whether, under the contract signed by the plaintiffs, they are obliged to set off their damages against the betterments. The practical difference between the contentions of the parties is that, in one view, the plaintiffs would recover a large sum for interest, and in the other view they would receive no interest.
The adoption of the order, including the assessment of land damages, followed by a seasonable construction of the street, •was an acceptance of the plaintiffs’ proposal in writing, in all the substantial matters to which the writing relates. This part of the writing is as follows: “ W.e, ... in consideration of the immediate laying out and construction of said proposed street at the width of fifty feet, . . . and of any assessments which may be laid upon our several estates for the cost of said laying out and construction being delayed until the damages caused to us severally by the taking of said land and the cost of the construction of said street shall be determined, and of said damages being offset against the proportionate part of said cost which may be levied upon our respective estates, agree that the payment for *574said damages shall be delayed until the balance due from us severally after making said offset has been determined.” The validity of such a contract, if accepted and performed by a city, is not now in question. Aspinwall v. Boston, 191 Mass. 441. Boston v. Simmons, 9 Cush. 373. Bell v. Boston, 101 Mass. 506. Driscoll v. Taunton, 160 Mass. 486. Everything in terms required to be done by the city, under the contract, was seasonably and properly done. The only thing which the contract calls for that has not been done is the determining of the balance due from the plaintiffs and others to the city, after making the offset. The contract assumes that the city will assess betterments, and that the amount assessed will be so great that there will be a balance due to the city after setting off the land damages. There is an implied agreement on the part of the city that it will make such an assessment, and do its part toward determining the balance due it. This agreement relates only to the adjustment of the accounts between the parties. If the city should neglect and refuse to do its part, after a demand or request by the plaintiffs, it might well be that the plaintiffs would not be obliged to delay longer the collection of their damages. In Aspinwall v. Boston, 191 Mass. 441, 447, it is said that, “ The important practical question is whether the stipulation as to the delay in collecting damages can be enforced against the plaintiffs, when the city fails to perform that part of the contract which calls for the immediate construction of the street.” At page 445, “ If the construction had been finished seasonably, in pursuance of the provisions of the writing, there would have been a complete acceptance by performance, which would have bound the city, as well as the plaintiffs, provided the contract is such as the representatives of the city had a right to make.” The opinion also recognizes the fact that, to do its whole duty under the writing, the city must be ready to offset the land damages against the betterments, and determine the balance which it was assumed would then be due from the plaintiffs. In that case the court had no occasion to consider the question whether a failure on the part of the city to assess betterments promptly after the completion of the work, when there was no request or suggestion by the landowners that an adjustment was desired, would be a breach of the contract, such as would *575entitle the landowners to sue at once for the whole amount of their damages. It would seem that every day’s delay in the assessment of betterments was an advantage to the landowners, for it postponed the necessity of paying to the city the excess of the betterments above the land damages.
We are of opinion that this setting off of one claim against the other and determining of the balance was to be done by the parties jointly, the plaintiffs participating in it, as well as the city. It was as much the duty of the plaintiffs as of the defendant to go forward and ascertain the balance. It follows that, until there was a neglect or failure of the city to do its part within a reasonable time upon a request by the plaintiffs, the city was not in default, and the plaintiffs were not relieved from their obligation to set off the damages against the betterments. There is little doubt that an assessment would have been made without much delay if the plaintiffs had asked for an accounting and a determination of the balance. See Averill v. Boston, 193 Mass. 488.
It is therefore unnecessary to consider how far the delay was justified by the litigation in other cases and the changes in the statutes, which have been referred to by the defendant as explaining its failure to make the assessment promptly.
The fact that the assessment was made under a statute enacted after the work was completed is immaterial. The writing binds the parties in reference to any assessment lawfully made to meet the expenses of the laying out and construction. Such an assessment may be made under a statute passed after the work is done. Hall v. Street Commissioners, 177 Mass. 434. Warren v. Street Commissioners, 187 Mass. 290. See Tapp an v. Street Commissioners, 193 Mass. 498.
Judgment on the finding.