Opinion by
Mb,. Justice Fell,The two main propositions upon which the appellant relies are: (1) that the plaintiffs’ obligation was not fulfilled by the construction of a reservoir in exact compliance with the terms of their contract with the city, but that they were bound to construct a reservoir through which water would not penetrate ; (2) that the director of public works had no power to make any change in the plans and specifications, and that for a construction made in compliance with the changes directed by him, there could be no recovery. To answer these propositions we must consider the terms of the agreement, the cause of the defects alleged, and the character of the changes which were directed.
The plaintiffs entered into a contract with the city to con*544struct a reservoir on a tract of land containing about sixty-five acres, for the sum of $1,159,591. The general agreement and the plans and specifications which were made a part thereof, together contain the most elaborate details as to the kind of' work to be done and the materials to be furnished.
The director of the department of public works is given the right to reject materials or work if unsuitable or defective; to supply other materials and employ other contractors or workmen in case the work should be done defectively or not prosecuted diligently; and, as between the contracting parties, he is-made the sole judge of the quality and quantity of the work done and materials furnishe'd, and of the meaning of any part-of the specifications. The contract provides that the materials shall be furnished and the work performed “ in strict and exact accordance with the plan on file in the department of public works and the specification hereto attached.” The provision for changing the contract is as follows: “ The contractor is bound to adopt any change of plans that may be deemed advisable, and an allowance shall be made for or against him, as the case may be, the amount of such allowance to be determined by the chief of the bureau of water and approved by the director of the department of public works and stated in writing previous to the work being done. Such alterations will not annul the contract except as to such altered parts.” In the specifications under the head of “ Approximate Quantities,” and following a. detailed statement of the amount of excavation to be made and of materials of various kinds to be furnished, is this sentence: “ The quantities are approximate only, and the director of the department of public works reserves the right to increase or diminish them as he may deem necessary.” Under one of the thirty subheads in the specifications, the work to be done is named in one sentence as the tearing down and removal of buildings, etc., the making of excavations, the construction of embankments and roadways, the seeding and sodding of the grounds, the building of walls, the lining of the interior slope, the building of walks and stop-houses, the removal of all surplus material, “ and all work necessary to make a complete and perfect reservoir ready for use and to leave the grounds in a suitable condition.” The last clause of this sentence, which closes a description of the numerous things to be done, in the construe*545tion of the reservoir and the ornamentation of the grounds with the general statement “ and all work necessary to make a complete and perfect reservoir ready for use and to leave the grounds in a suitable condition,” is the basis of the contention that it was the duty of the contractors to turn over to the city a reservoir that would not leak, although the one they constructed and delivered was in exact accordance with the plans and specifications. The leaking of the reservoir appears to have been due to the insufficient thickness of the clay bottom. The clay used would have been sufficient if it had rested upon solid rock; but the foundation of the reservoir was micaceous rock which contained fissures, through which the water which percolated through the clay found an outlet. This defect in the reservoir was not due to defective material or workmanship in its construction. To hold the plaintiffs answerable for it would be to hold them as warranting that the reservoir should be a perfect reservoir, notwithstanding that its defects might be due entirely to its site or to the specifications. This is precisely the position taken by the city, and it cannot be sustained.
The contract does not admit of such a construction. It was not at any time a fixed and certain contract, as the city through her officials could make any changes which were deemed necessary, and the contractors were bound to build as directed. The words, “all work necessary,” etc., follow the enumeration of the things to be done, and they were doubtless intended to cover points of construction which might have been overlooked, or which might afterwards be found to be necessary, or which could not then be specified, as the working plans had not been completed. The contractors were given no discretion. Every line was drawn, every grade was fixed and every detail was provided for by the city. If the contractors had thought it wise to depart from the plans, and had done so and built a better reservoir, they could have recovered nothing. There would have been a deliberate and wilful departure from the terms of • the contract which would have defeated their entire claim for the price. We cannot conclude that, under an agreement which might be changed from time to time, and in which the only certain thing was that materials should be furnished and work performed “in strict and exact accordance with plans and specifications ” prepared or to be prepared thereafter by the *546city, it was intended that the contractors should do more than make a reservoir complete and perfect according to the plans and specifications furnished. The words “ all work necessary to make a complete and perfect reservoir ready for use,” found at the end of one of the specifications in which the kind of work to be done is described, when read in connection with other parts of the agreement, do not indicate an intention that the contractors were to be responsible for the result if there was no default on them part.
This is not the case of an undertaking absolutely to construct a particular thing, or to construct a thing according to plans furnished by the builders, or of a failure because of accident to the works or the sinking of the foundation on which the structure was to stand. The failure to obtain the result desired was not owing to the failure to do the work as agreed, but to causes over which the plaintiffs at no time had control.
By ordinance the director of the department of public works was instructed to prepare plans and specifications and to award the contract for the construction of the reservoir. The contract prepared by him and approved by councils bound the contractors to adopt any change of plans that might be deemed advisable, the allowance in cost for or against them to be determined by the director, and full power was given the director to increase or decrease the amount of excavation and of materials of all kinds specified. The contract authorized and entered into reserved to the city the privilege of making changes in its terms as the work progressed, and either by expression or by direct and necessary implication the director of public works was empowered to make such changes, and was constituted the sole arbiter to determine the meaning of the specifications, and whether they had been complied with. As to the wisdom of delegating the power to change municipal contracts much might be said on either side. The delegation of such a power furnishes the opportunity for its abuse, but it seems to be almost essential to the prosecution of works of great magnitude. It is not the experience of life that large confidences are betrayed more frequently than small ones. It is conceded in this case that the changes were honestly made for the benefit of the city. The important changes made were suggested by the experience the department had had with other reservoirs after the contract *547was entered, into, and none of them increased the cost of the work. But we are concerned with the question of power only. We are not dealing with alterations in a contract made without authority, or which radically change the general character of the work, but with those expressly authorized and provided for, which concerned only the details of construction. If the contract had not permitted changes it would not of course have been within the power of the director to make them, but we see no reason to doubt the power of the city to provide in the contract for such changes as were made and to authorize the director to make them.
The learned judge in his charge clearly stated the law as to substantial performance and instructed the jury that if there had been no wilful departure from the contract or omission in essential points, and the contractors had honestly and faithfully performed their contract in its material and substantial particulars, a forfeiture of the right of remuneration would not arise by reason of merely technical, inadvertent or unimportant omissions or defects, and under the evidence in the case we cannot say that there Avas any error in refusing the defendant’s fifth point. The instruction asked for was that if there had been substantial but not strict performance the defendant was entitled to such a deduction as would compensate for deficiencies. Where there is a recovery for substantial performance notwithstanding defects, there should be a deduction as a compensation to the defendant: Monocacy Bridge Co. v. Am. Iron Bridge. Mfg. Co., 83 Pa. 517. But there must be proof as a foundation for the claim for an allowance. The learned trial judge, in answering the point, said that the law was correctly stated, but that there was no evidence of the cost of repairs, and our attention has been directed to none which would have justified an allowance on any ground.
The judgment is affirmed.