Morton, J.
The main question in this case is whether the agreement entered into with the plaintiff by the defendant through its street commissioners with the approval of the mayor *122and on which this action is brought is valid. There also,are questions of interest and of the admission and exclusion of evidence. The questions of evidence may be disposed of shortly with the remark that the circumstances which led to the passage of the statute and the making of the agreement in suit under it were competent and were rightly admitted to aid in the construction of the agreement, and evidence to show that the agreement was advantageous to the plaintiff and disadvantageous to the defendant was incompetent and immaterial and was rightly excluded. We see no error on the part of the auditor or of the judge in dealing with matters of evidence.
We come then to the main question and it seems to us plain that the agreement is valid. The mayor and aldermen of the defendant filed a petition in 1892 under the grade crossing act for the abolition of the grade crossing of the Old Colony Railroad Company and Dorchester Avenue. Commissioners were appointed and hearings were had with the result that the public authorities came to the conclusion that the public benefit would be promoted by and required improvements of greater scope than those contemplated by the abolition of the single crossing to which the petition related. A plan was agreed upon which was satisfactory to the Commonwealth and the city and to which the plaintiff made no objection from an engineering point of view. This plan contemplated extending a number of streets across the location of the railroad and changing the existing location for another and laying out a street or boulevard along so much of the old location as the railroad would thus cease to occupy. The railroad company objected to this plan on account of the expense to which it would thereby be subjected, and refused to consent unless some arrangement was made so that the net expense to it should not exceed the expense to which it would be put by abolishing the Dorchester Avenue crossing, which was estimated at $875,000. As the law then stood the proposed improvements could not be carried out without the consent of the railroad company. The mayor of the defendant thereupon proposed to the railroad company, in substance, that if it would agree to the plan and would also agree that the commissioners might go on under the proceedings then pending and make the changes required by the proposed plan the city would *123pay to the railroad company the difference between its share of the estimated cost of abolishing the Dorchester Avenue crossing, $875,000, and the cost of making the changes and abolishing the crossing in the manner desired by the city. The railroad company agreed to this proposition and thereupon the city was allowed, with the assent of the railroad company, to amend its petition so as to ask for the abolition of the crossing in accordance with the plan thus agreed upon. St. 1897, c. 519, was then passed by the Legislature and the agreement in suit was entered into under the authority which was supposed to be conferred by that statute on the city, and which we think it is plain was conferred. It is expressly provided in § 3 of that act that “the board of street commissioners of said city, with the approval of the mayor, may agree with the directors of said Old Colony Railroad Company upon an amount to be paid by said city to said railroad companies (i. e. the Old Colony and the New York, New Haven and Hartford Railroad Companies) for land taken from, and for damages sustained by, said railroad companies under this act, taking into consideration in determining the same the benefit to the public by the carrying out of the provisions of this act, and the amount so determined shall not be included in the cost aforesaid to be paid by said railroad company, state and city.” It is objected that the amount is not fixed by the agreement. But there is nothing in the statute which requires that it should be. That is certain which can be made certain, and it is plain that the amount could be ascertained by deducting, from the total amount which the plaintiff was obliged to pay as it's share of the improvement, the sum of $375,000, which was agreed upon as its share of the estimated cost of abolishing the Dorchester Avenue crossing. It also is objected that unless the amount was fixed in the agreement the city might exceed its debt limit. But that was a matter within the control of the defendant and for which the plaintiff cannot be held liable.
The remaining question relates to interest. The agreement provides that the city shall pay the plaintiff the sum agreed upon “ with interest at four per cent upon the payments from time to time made by said railroad company as its sixty-five per cent, in excess of said sum of three hundred seventy-five thou*124sand dollars, until the amount to be paid under this agreement is paid.” This clearly fixes the rate of interest and provides expressly for the payment of interest until the amount to be paid by the city under the agreement shall have been paid. The fact that the plaintiff could not call upon the city for payment until its president gave notice to the mayor that the land comprised in the old location had been abandoned and that the city might enter and take possession thereof would not prevent the running of interest as agreed. The auditor computed the interest by adding together the interest at four per cent on each item of expenditure by the railroad company, including payments to the city, after the expenditures reached the sum of $375,000 down to February 4, 1903, which was the date of the last payment made by the railroad company under decree of court, and subtracting from the total, interest on all sums received by the company from the Commonwealth, and then computing interest from February 4 on the principal sum. This method was adopted and confirmed by the judge of the Superior Court who heard the case and was, we think, correct. The result is that the finding of the Superior Court is affirmed and
Judgment ordered accordingly.