Another provision of the charter (sec. 26, c. 2, art. VI), relating to the definition of terms, and the use of patented pavements in street work in the city and county, provides: "The word 'paved' shall include any pavement of stone, iron, wood, or other material which the supervisors may by ordinance order to be used; but no patented pavement shall be ordered during the existence of the patent therefor, until the owner of such patent shall have transferred to the city and county all right to the use of the same therein, with the privilege to any person to manufacture and lay the same upon the streets under any contract that may be awarded to him with the city and county." The trial court found that the supervisors did not, at any time, order the laying of a patented paving on Mission Street, and that the further provision of the section just quoted relating to the transfer of the right to use the same had not been complied with by petitioner in this case, "except as such transfer may be found in the contract entered into by petitioner and the board of public works."

This contract consisted of two parts. As they appear in the findings the first is a formal agreement between the petitioner and the board of public works, acting for and on behalf of the city and county. It refers to a "License Mixture Agreement" filed by petitioner with the board, which is made a part of the contract, and to a resolution of the board, executing the contract, referring to the license mixture agreement, and approving the specifications therefor. By the agreement petitioner agrees to furnish the city and county the material and the services provided in the license mixture agreement, at the rate of, and the city and county agrees to pay therefor, seven ($7) dollars per ton of said wearing surface. The license mixture agreement, made a part of the contract, contains these provisions: "Whereas, it is deemed advisable by the proper authorities of the city and county of San Francisco, state of California, that portions of Mission Street, and of such other accepted public streets in said city and county as may be determined by the said authorities, be paved with the Bitulithic pavement, under and in accordance with approved specifications, a copy of which is attached to and made a part hereof, and Whereas, the said improvement requires the laying of a certain patented Bitulithic wear

42 Cal. App.-17

ing surface and seal coat, and Whereas, the undersigned, Warren Brothers Company, is the owner of all patents and processes covering the said Bitulithic pavement, Warren Brothers Company hereby proposes and agrees to furnish to the city and county of San Francisco, at any time up to and including December 31, 1917, the following materials ready for use, as specified and required under and by said specifications: 3. The right to use any and all patents owned or controlled by Warren Brothers Company which are necessary to be used in the laying of said pavement, and the perpetual right to use and repair or reconstruct the patented pavement so constructed. The right of the city and county to repair or reconstruct such pavement with such patented material or other material, is hereby reserved in this proposition to said city and county. 4. . . . This agreement shall inure to the benefit of said city and county of San Francisco and of any person to whom any contract may be awarded by, or entered into with, said city and county of San Francisco for the performance of said work." Then follows full details and specifications relating to the "construction of Bitulithic Wearing Surface," which appears to be the proper name for said patented wearing surface.

We are of the opinion that there was a sufficient compliance with the charter provisions relative to the transfer to the city and county of the right to the use of the patented wearing surface. While the language might be more explicit as to the privilege granted any person to manufacture and lay the same upon the streets under contract awarded to him, or entered into by the city, we think the intention to comply with the requirement of the charter is manifest, and that we are right in so holding.

Much of the argument of counsel in the numerous briefs in this case has been devoted to the question of this use by the city of the patented wearing surface, which was laid on the concrete base, on Mission Street, as reconstructed. On oral argument this question was referred to as the principal contention. [8] That such patented composition, or mixture, may be used, if called for by proper jurisdictional procedure, is settled. (Nicolson Pavement Co. v. Painter, 35 Cal. 699; Dunne v. Altschul, 57 Cal. 474; Sarver v. Los Angeles, 156 Cal. 187, 189, [103 Pac. 917].) The

charter provision we have heretofore quoted provides for such use in the city and county of San Francisco. Appellant contends that the board of public works, although required to let all contracts to the lowest bidder, may, nevertheless, let a valid contract for improving its streets by a patent process and subject to a monopoly. Such is undoubtedly the law relating to the purchase of patented articles generally, such as fire-engines, machinery, furnishings for public buildings, and ordinary supplies. But the framers of the San Francisco charter had a well-defined object in view, in the enactment of the section in question, the purpose of which was to secure active competition, regardless of the use of a patented pavement in the improvement of its streets. [9] We are not prepared to hold with appellant that the provision shall apply only in case of street work on unaccepted streets, in which case the proceedings are in invitum. All street work in the city and county, except, possibly, urgent repairs, shall be done on the order of the board of supervisors. No patented pavement shall be ordered by the supervisors until the owner shall have made the assignment, required by the section, of the right to use the same, with the privilege to any person to manufacture and lay the same upon the streets under any contract that may be awarded to him, or entered into by him with the city and county. This jurisdictional step taken, the board of public works is in position to follow the provisions of the charter, in the matter of securing sealed bids for the furnishing of such quantities of the patented pavement as may be necessary, as in the case of ordinary supplies. (Nicolson Pavement Co. v. Painter, supra.) On such bids being called for the owner of the patents governing the pavement, and all other bidders, are in position to compete for the contract which should be awarded the successful bidder in the manner provided in the contract. To hold otherwise would, in our judgment, be doing violence to the intent and terms of the charter.

Two situations are to be dealt with: First, the board of supervisors did not "order" the reconstruction of Mission Street; second, the contract between petitioner and the board of public works was entered into without the formalities required by the charter, although the contract has

been fully performed to the satisfaction of the board, and the city and county has received the full benefit thereof. To meet these situations petitioner relies, first, upon the effect of the ordinance of ratification, adopted after the doubt as to the regularity of the proceedings by the board of public works presented itself, and, second, it invokes the doctrine of equitable estoppel.

After reciting the facts relating to the matter, much as they appear here, the said ordinance ratifies, approves, and confirms the purchase of the paving material by the board of public works, confers authority on said board "to do all of the acts hereinbefore set forth as fully as if such authority had been conferred prior to the doing of said acts," and appropriates "the sum of $7,756 for payment to Warren Brothers Company for the wearing surface material purchased from the said company by said board of public works, etc." [10] We are of the opinion that this ordinance had the effect, contended for by appellant, to cure the omission of the board of supervisors, in the first instance, to order the work of improving the street, and the laying thereon of the patented wearing surface. (People v. Swift, 31 Cal. 26, 28.) As an ordinance was necessary in the first instance to inaugurate the work, it was proper that the ratification be in the form required in the original When passed its effect was equivalent to a previous authority. It operated upon the action of the board of public works as though the authority had originally been given. (McCracken v. City of San Francisco, 16 Cal. 591; Cottman v. City and County of San Francisco, 20 Cal. 96, [81 Am. Dec. 96].)

[11] The contract between petitioner and the city and county, by and through its board of public works, for furnishing the material used in the improvement of Mission Street, did not arise from, or result in, proceedings in invitum, whereby any interests of third parties could be affected. In improving one of its accepted streets the municipality was acting more in a proprietary than in a governmental capacity. It was to all intents and purposes caring for its own property as an individual or private corporation would do. "When a municipal corporation engages in ordinary business transactions, such as purchasing supplies, it exercises merely the right of a private

corporation or a natural person; and when making contracts about such matters it is not to be regarded as exercising political or governmental powers; and, like natural persons, it is subject to the principle that after it has received the benefit of a contract within the scope of its power to make, it is estopped from denying its validity in an action based upon such contract." (Contra Costa Water Co. v. Breed, 139 Cal. 432, 436, [73 Pac. 189, 191].)

"Substantially the authorities indicate no different rule in applying the doctrine of estoppel to the acts of individuals or private corporations, than is proper to be applied to the acts of municipal corporations. There is, however, a distinction suggested, and it is this: That where the contract or agreement upon which recovery is sought is one wholly without the scope of the municipality to makein other words, is ultra vires-then there can be no estoppel; but where the authority exists to make the contract, but the proceedings precedent thereto have been informally taken only, then the rule of estoppel may be made to operate against a municipality as it would against an individual under the same circumstances. (McCormick Lumber Co. v. Highland School Dist., 26 Cal. App. 641, [147 Pac. 1183].)

The board of supervisors clearly had the general power to provide for the purchase, by the board of public works, of the supplies, including the wearing surface, necessary for the improvement of Mission Street, whatever the contention may be about the manner in which the contract for such supply ought to be made. Even if it be that certain provisions of the charter, or ordinances, were not strictly complied with, the city, under well-settled legal principles, should not be allowed to accept, use, and retain the benefit of petitioner's property, and then refuse to pay for it upon the plea that in making the contract it has not proceeded in strict conformity with some part of the complicated internal machinery of its complex corporate organization. (Contra Costa Water Co. v. Breed, supra; Higgins v. San Diego Water Co., 118 Cal. 555, [45 Pac. 824, 50 Pac. 670]; Brown v. Board of Education, 103 Cal. 534, [37 Pac. 503].)

The judgment is reversed.

Richards, J., and Kerrigan, J., concurred.