This is an action brought by a contractor against a property holder in San Francisco, to enforce a lien and payment for work done in grading Mason Street from O’Farrell to Ellis streets. The defendant demurred to the complaint on the ground that it did not state facts sufficient to constitute a cause of action, and that it was ambiguous, unintelligible, and uncertain. The Court below sustained the demurrer, and, the plaintiff failing to amend his complaint, rendered a final judgment for the defendant, from which the plaintiff appeals.

It appears from the complaint that the work was not completed within the time limited in the contract, but the time was twice extended by the Superintendent of Streets, and it is insisted that the Superintendent had no power to enlarge the time, and therefore the plaintiff has no right to recover. We held in the case of Conlin v. Seamen (ante, 546), that the Superintendent had full power and control over the matter, and that an extension of the time by him did not release the property holders from their liability to pay the assessment.

*553The complaint avers that the proceedings for the grading of this street commenced on the twenty-seventh day of August, 1860; that the Superintendent of Streets, on the twenty-third day of November, 1860, entered into a contract with the plaintiff to do the work; that he performed the work, which was duly approved by the Superintendent, who, on the fourth day of October, 1861, assessed and apportioned the amount upon the adjacent lots, each lot being separately assessed in proportion to the assessed value of the same, according to the assessment roll last completed prior to the making of the contract. The defendant insists that the assessment is void, because not made in accordance with the provisions of the Act of May 18th, 1861, which was in force when the assessment was made, and which provides that “ the expense of construction of any street, or portion of a street, shall be assessed upon the lots of land fronting thereon, each lot or portion of a lot being separately assessed, in proportion to its frontage, at a rate per front foot to cover the total expenses of the work.” On the contrary, the plaintiff contends that the law in force at the time the contract was made—the Act of March 28th, 1859—controls the rights of the plaintiff, and that the assessment, being made in accordance with that law, is valid. The difference between the two statutes is simply this—the Act of 1859 provides that - assessments shall be according to the value of the lots, and the Act of 1861, according to the street frontage of each lot.

The plaintiff made the contract, in view of the right, which the law then in force gave him, to resort to the property and its owners for payment of the work done in grading the street. In this respect the law of 1859, so far as it regulated the extent and nature of that liability, formed part of the contract, and could not be essentially changed without impairing the obligation of the contract, which could not be done without a violation of the Constitution. The Act of 1861 changes the rights of the plaintiff and the liability of the property and its owners, by changing the extent of that liability— making some to pay more and others a less sum than they would have been liable to pay under the Act of 1859. Such a result can only be avoided by giving the Act of 1861 a prospective effect—that is, limiting its application to those contracts made after it took effect. *554It is a well settled ride of law that statutes should not receive a retroactive construction, unless the intention of the Legislature is so clear and positive as by no possibility to admit of any other construction. (Sedgwick on Stat. and Con. Law, 193, 407.) There is nothing in the language of the Act of 1861 amendatory of Sec. 36, which makes it necessary to give it a retroactive effect, so as necessarily to include contracts made before its passage, and it should therefore be construed to apply only to subsequent contracts. (Creighton v. Pragg, 21 Cal. 115; Scarborough v. Dugan, 10 Id. 305.)

It is also urged that the Board of Supervisors have no power to initiate proceedings for the grading of streets east of Larkin; and, as this street is east of Larkin, therefore the whole proceedings are void, for want of jurisdiction. Sec. 39 of the Act of 1856 gives the Board power to lay out and open new streets within the former corporate limits of the city, and west of Larkin and south-west of Johnson streets. Sec. 40, as amended in 1859, gives them power, “ when any street is located,” to order it graded. This evidently applies to all located streets, whether new or old, and this point, therefore, is not tenable.

The judgment of the Court below is reversed, the order sustaining the demurrer is set aside, and the defendant is allowed ten days, from the service of a notice of the filing of the remittitur in the Court below to answer the complaint.*