Mr. Justice Morkis
delivered the opinion of the Court:
1. By concession of counsel for the District of Columbia in open court in the hearing before us, it now appears that the claim of the District to the items in schedule D, for work in Georgetown amounting to $15,292.63, is without foundation; and that this sum in any event must be deducted •• from the demand of the District, which is thus reduced to the sum of $132,214.42. The work done on the streets of Georgetown specified, in this schedule had been done before, the railroad company had begun to occupy these streets in any manner; and when it did occupy them, it repaired the streets at its own expense, and continued to keep them thereafter in good order and .condition. The claim of the District in this instance'was wholly erroneous and is so shown by the record; and the attorney for the District could ■ scarcely do otherwise than abandon these items.
2. On the other hand, the item of $1,914.52, in schedule.. Ba, for work done on Boundary street, is scarcely open to [344]*344discussion. That work was done in the summer of 1875, after the railroad company bad fully occupied the street and was running its 'cars thereon ; and the material used for paving, which was Belgian block, was well suited for the purposes of the company, and a durable pavement. And this sum of $1,914.52 must, therefore, be adjudged in favor of the District of Columbia in any event.
3. With reference to the items contained in schedules B and C, both of which stand upon the same basis, it appears that while the railroad company under its charter had the right of constructing its branch lines of road upon the streets therein mentioned, it had not in any manner exercised that right when the Board of Public Works entered upon those streets and undertook to lay the pavements with part of the cost of which it is now sought to charge the railroad company. The company had still about two years in one case and nearly three years in the other within which to construct these lines ; and it ^alleged, and it may be assumed to have been the fact, that its resources at the time were unequal to the expenditure that would be entailed by the work of construction. In this condition of things the president of the railroad company addressed, on October 26, 1871, the following communication to the Board of Public Works :
“ Washington, October 26, 1871.
“ To the Hon. Board of Public Works of the District of Columbia.
“ Gentlemen : Your board having recently ordered the paving of certain streets through which Congress had given this company permission to lay rails whereon to run street cars, we would respectfully ask the privilege to lay down the sleepers and crossties as the paving progresses, thereby preserving the streets and avenues from being cut up at a future day in the execution of this work. It is the intention of this company to extend the Metropolitan Railroad westward from its present terminus to Georgetown and eastward to Uniontown, and also to lay tracks on Ninth street [345]*345to Pennsylvania avenne, to the Boundary, and on 4^ street from the city, hall to the arsenal gate as soon as the property holders along these lines subscribe to additional stock, which, it is hoped, will be done shortly. The company are willing, with the permission of the board, to go on at once and lay the timbers for these lines, fully preparing them for the rails to be put in at some future time. To keep a well-laid pavement in good order it is desirable to avoid all excavation, particularly in the center of the street. This consideration doubtless influenced your board in its wise precaution of ordering all water, gas, and service pipes to be laid prior to the paving. ■ The, necessity is more apparent, where railroad privileges have been granted, to have the timbers laid as the paving progresses, which will not only be a benefit to the city, but add to the comfort of those residing upon or passing over the street. We are willing to anticipate the putting down of the sleepers and crossties of our contemplated extensions, provided the paving be done by your own contractor without charge • against us-, and should be pleased if the suggestion herein submitted should meet the favor of your board.
“ Very respectfully, your obedient servant,
“ J. W. Thompson, President
The answer of the Board of Public Works to this communication would seem to have been the passage by it on the same day (October 26, 1871,) of the following resolution :
“ Resolved, That when this board shall have authorized the paving of a roadway of any street or avenue along which any horse railroad company is empowered to lay railroad tracks, such company shall have the privilege of laying, at its own expense, the sleepers, crossties, and other woodwork of such tracks in advance of paving, so as to prepare the track for the rails and thus prevent the necessity of disturbing the pavement for this purpose at a future time; said work to be done under the direction of the board.”
[346]*346In pursuance of this resolution, and of the understanding created thereby, the railroad company at its own expense laid the'sleepers and crossties on Ninth street and East. Capitol street, while the pavements were being laid by the Board of Public Works ; but it did not lay its rails or begin the running of its cars until some time after the laying of the pavements had been completed. How long this was does not appear from the record before us.
Substantially the same conditions prevailed and the same action was taken with regard to Seventeenth street, between H and I streets, and Connecticut avenue, which are the subject of schedule C.
The liability, therefore, of the railroad company to the District of Columbia, in regard to the items contained in these two schedules B and C, depends upon the determination of the question, whether by laying down its sleepers and crossties under this resolution adopted by the Board of Public Works, the railroad company immediately thereupon so occupied the streets and avenues upon which it had been authorized to construct its road, as to become liable to the District of Columbia for the cost of paving then done by the board on the portion of the streets and avenues thereafter used by the railroad company. This question we musL answer in the negative.
Evidently it was not the understanding or intention of the Board of Public Works at that time to order the paving of any portion of these streets or avenues to be done by the railroad company. Nor was it the intention to charge the railroad company with any portion of the cost; for no charge. therefor was ever made by the board against the company. And so far as the understanding of all the parties at the time can avail in the consideration of the question, it is beyond all doubt that the railroad company was not supposed to have incurred, by the action which it took, any liability whatever on account of the paving.
The arrangement suggested by the letter of the. president of the railroad company, to which evidently the resolution [347]*347adopted by the Board of Public Works was intended as a reply — although the resolution properly provided that the arrangement should be general and should apply to all proposed railroads, and not alone to the defendant in this case —was an arrangement certainly beneficial to the public as well as' to all the parties in interest. If it were a cunningly devised scheme to enable the railroad company to evade the duties and liabilities imposed upon it by its charter, a different case might be presented here. But there is no pretence of bad faith on the part of the railroad company or of any one else in this connection. The street railroad business was in its infancy at the time. Its success was not assured. The defendant, it is conceded, was without present resources to construct the proposed branch lines. It did not propose to construct them at that time; and it had by law' the right to postpone their construction for a further period. It had the unquestionable right, if it had chosen to exercise it, to remain silent, to let the Board of Public Works proceed with its work of paving, to wait until that work was done, and then to enter upon the streets, construct its road and gain the benefit of the paving that had been done by the board without any liability to pay for it. Even if it could be conclusively shown that the railroad company had so postponed all action by it under its charter, for the express purpose, secret or avowed, of availing itself of the intermediate labors of the public authorities, it is not apparent how, under the law, it could be held liable for the cost of those labors. Its charter does not require it to pay for any pavements already laid upon any of the streets upon which it is authorized to enter. That charter merely requires it to keep the spaces occupied by it in those streets well paved and in good order; and that requirement would involve the necessity of laying a new' pavement, if none were already there ; but it certainly does not involve liability to pay for a pavement already in existence. Had Congress intended to impose such liability upon the company it could easily have said so; and it might have been proper to do [348]*348so. But neither in the charter nor anywhere else has it said anything that could by any possibility be construed to involve such a liability, and we do not understánd that any such liability is claimed by.anyone in behalf of the plaintiff in this case.
The claim is that the laying of the sleepers and crossties by the railroad company in advance of the work of paving by’the Board of Public Works or simultaneously with it, was such an appropriation of the streets by the railroad company to its own use as to constitute, in contemplation of law, a construction of its railroad upon the streets in question, so as thereby to render it liable under the statute, for the cost of the pavement. But this we must regard as an unreasonable application of the statute.' The reason of the law demands no such construction; and we do not think that the language of the law justifies it.
.The laying of sleepers and crossties in a street, whereon afterwards to construct a railroad, does not of itself appreciably diminish the use of the street by the public ; nor does it appreciably increase the wear and tear of the roadway. • The crossties are usually buried out of sight, and form merely a substratum that would not affect the ordinary uses of the street in any way; and the sleepers are usually laid even ■ with the surface of the street, and do not of themselves impede travel or interfere with the use of the street by the general public. It is the use of the street by the railroad company with its horses and carriages and its superior right of way for its horses and carriages along its line of tracks-that restricts the public use and subjects the street to the wear and tear that justifies the requirement in the charter which provides that the company should bear the expense of keeping well pavpd and in good repair the portion of the street so devoted to its franchises. And while it is true that, for some purposes, the act of occupation should be construed to begin with the first beginning of the w,ork of construction, and from the very first moment at which the railroad .company enters upon the street, yet a--partial and [349]*349disconnected act, not understood or intended by anyone to be an act of definite and permanent appropriation, should not be given that effect when there is no public purpose to be subserved by it, and when the express intention.of all the parties was to the contrary. When it is remembered that by simply waiting until the work was done, the railroad company could have had the benefit of that work', and at the same time could have escaped liability for its cost, ft is difficult to see why, in the absence of any express provision of law to that effect, there could have been illegality in an arrangement of which the purpose and the' necessary result was to save expense, inconvenience and annoyance to the public. And assuredly it is no objection to the arrangement in this. regard that it ultimately also saved expense to the railroad company.
The Board of Public Works, as is clear from the statute; and as has frequently been held, had entire charge and control of the matter of paving the streets and avenues of the - city of Washington. For the purpose of paving it could and did use wood and other materials. And if wooden beams were fit for a portion of the street, and some one was willing to put down such beams without' expense to the public, it is difficult in reason to see why the public or the District of Columbia might not lawfully accept the gift. It was not proposed at the time to make any other use of these beams. For the time they were wholly and exclusively for the benefit of the public. And it does not alter the case at all that afterwards iron rails could and would be attached to them, and that thereupon,the whole structure would be subjected to a special use, different from the public use. It is plain that, under the circumstances, it is this attachment of iron rails and the special use thereafter made of the structure that constitutes, for present purposes, the appropriation of the street by the railroad company.
That this was the intention also of Congress is quite- apparent from the language of the statute itself. For the requirement of the statute is that the railroad company should [350]*350“ keep said tracks and for the space of two feet beyond the outer rail thereof, and also the space between the tracks, at all times well paved and in good order.” Until there are tracks and an outer rail, it is not apparent how there can be anything to be kept well paved and in good order. The duty of paving or of keeping the specified spaces well paved and in good order evidently does not arise until the rails are laid and the structure becomes a railroad track. As we have said, if Congress had intended that railroad companies receiving the privilege of constructing and operating their lines of railroad in the city of Washington should not exercise that privilege without paying for the cost of pavements which thereby became devoted to their use, it could easily have said so ; and there would certainly be no great injustice in the requirement. But it has not thought proper to say so, and the courts cannot add a liability which the larv does not impose.
We desire to repeat that we do not mean to say that there may not be liability on the part of the railroad company from the first moment that it enters upon a street in any manner. If it put down only one sleeper or one cross-tie, or only displaced one shovelful of earth, and damage resulted to some one from negligence connected wfith the act, the company would undoubtedly be liable to the person so injured. And so of other cases that may readily be conceived. What w'e hold here is that, under the acts of Congress which constitute the charter of this defendant railroad company, the duty of paving or of keeping the spaces allotted to it w'ell paved and in good condition, does not arise until there are rails laid and a track constructed— not necessarily all the rails laid or the entire track constructed, but some appreciable space of rail and track in respect of which the duty may arise.
The decisions cited in this connection by counsel on behalf of the District of Columbia w'e cannot regard as in any manner contravening this position. The case of Railway Co. v. Alling, 99 U. S. 475, is cited to show that, when [351]*351a railroad has been definitely located, the title to lands granted to it, previously imperfect, thereupon becomes definite and specific. The case of State v. Winona, 21 Minn. 472, and State v. Southern Minn. Railway Co., 21 Minn. 344, are referred to for the purpose of showing that, with a view to the taxation of property, a contract to convey is to be regarded as the equivalent of a conveyance. And Brooks v. Railway Co., 101 U. S. 443, and Meyer v. Hornby, 101 U. S. 728, are cited to show that a railroad, although constructed in sections, is practically one structure for the purpose of the enforcement of a mechanic’s lien claim for work done on one of the sections. And no doubt numerous other cases of a similar character might be cited. But we fail to see their application to the question before us. The gist of all these cases is that, when one has the beneficial use of property, he should be liable for its burdens — a most just and equitable doctrine. But this does not tend to show that one should become liable for such burdens before he becomes entitled to the beneficial use of the property.
Sleepers and crossties do not constitute a railroad. Indeed, we might conceive a railroad without them. It is the imposition of rails upon the substructure that constitutes the definite character of a roadway as a railroad. And it is only when a railroad company has the definite use of a railroad that it becomes its duty to keep that roadway paved. It may have antecedent duties, but those duties are of a different character.
We concur with the special commissioner in holding that, in respect of the items charged in schedules B and C of his report, the plaintiff is not entitled to recover anything from the defendant.
4. With regard to the plaintiff’s claim as set forth in schedule A of the report of the special commissioner, another and a very different question is presented.
That schedule comprises the work done on the streets and avenues of the city of Washington whereon the main [352]*352line of the defendant’s road had been constructed and on which the road had been in actual operation for several years before the Board of Public Works commenced its plan of improvement. On these 'streets and avenues, on some or all of which there had been no previous pavement of any kind, the railroad company had paved its entire track and all the spaces prescribed for it by the statute in á good and substantial manner, with a pavement of cobblestones well suited to its purposes and entirely satisfactory to the authorities of the city of Washington and of the "District of Columbia. The Board of Public Works resolved and undertook to pave all these streets with concrete or wood, one space only with Belgian block. Entirely ignoring the railroad company and the existence of the railroad tracks, it entered into contracts for paving the whole roadway from curb to curb, and made no allowance even for the spaces actually occupied ■ by the rails, although in the aggregate these spaces amounted to a very considerable sum. And it may be noted here, that, in the demand made in 1880 by the District of Columbia upon the railroad company and in the declaration filed in this suit, the charge made against the railroad company included the supposed cost of work which was never done and could not have been done, the paving of the spaces occupied by the rails of the company’s railroad, amounting in the aggregate to the sum of $9,785.89. But, as already stated, this is now conceded and allowed to be a proper deduction from the amount of the claim.
Against the protest of the railroad company, the Board of Public Works, by its contractors, proceeded to remove the cobble-stone pavement laid by the railroad company; appropriated the cobble-stones to the use of the District, without, in the first instance, giving any credit for the value thereof to the railroad company, although the credit is now conceded, amounting to $5,330.01 ; and laid what proved to be a worthless pavement of -wood and concrete, which soon rotted or crumbled and became dangerous to the [353]*353horses, and which in a short time the railroad company found itself compelled to remove, which it did with the acquiescence of the authorities of the District of Columbia, replacing it at its own expense with a new cobble-stone pavement. It is this worthless pavement, so laid, for which compensation is here sought by the District of Columbia from the railroad company.
Upon this statement of facts, which are undisputed and beyond. dispute, if this were a controversy between two private corporations, or between two private individuals, or between a private corporation and a private individual, and the controversy were to be determined on principles of equity and justice, there could scarcely be much hesitation as to what the decision should be.. But there are other and most potential considerations in this case that cannot be ignored.
We are dealing in a measure with' the sovereign power of the State. The District of Columbia, it. is true, is only a corporation ; it is not the State ; and the Board of Public Works was only a subordinate, although very powerful, agency within the corporate administration. And the District of Columbia, as determined in this very case by the Supreme Court of the United States, is not entitled even to immunity from the bar of the statute of limitations. But it is nevertheless a municipal corporation, armed with one of the most formidable powers and attributes of sovereignty, the power of taxation, and charged by the sovereign power as its representative with the control and proper maintenance of the public highways. Over these public highways its control from the State is supreme; and all other agencies are subordinate to it. When Congress permitted and authorized the defendant railroad company, a purely private corporation, although subserving a public purpose and to be regarded perhaps as performing a public function, to appropriate to itself to a limited extent a portion of the public highway, and in consideration of that privilege required it to keep such portion of the highway well paved and in [354]*354good repair, it did not mean to relieve the city of Washing-ton or the District of Columbia, as a municipal corporation, from the"performance of the-superior duty in the same respect imposed by law upon the municipality. There was undoubtedly a duty imposed by the sovereign upon the railroad company ; there was a superior duty imposed upon the municipality and a superior power granted to it. The municipality is the immediate representative of the sovereignty ; the railroad company is no more than an inhabitant of the municipality, subject, like all other inhabitants, to the municipal ordinances, and by the special provision of the law in this case, subject as to all the use and maintenance of its road to'all the municipal regulations.
The city of Washington had been authorized and required “ to open and keep in repair the streets and avenues ” of the city (Act of May 15, 1820, 3 Stat. 583). Under the so-called territorial organization, the Legislative Assembly of the District of Columbia, which was no more than the municipal council of the District, was given “ the care and charge of and the exclusive jurisdiction over all the public roads” of the District (Act of Feb. 21, 1871, 16 Stat. 420). And by the same act it was given to the Board of Public Works “ to have entire control of and make all regulations which they shall deem necessary for keeping in repair the streets, avenues, alleys and sewers of the city.”
In view of this legislation it can scarcely be supposed that, when Congress in its grant to the railroad company required that organization to keep the portion of the street occupied by it well paved and in good repair, it intended thereby to withdraw such portion of the street from the control and jurisdiction of the municipality, and commit that control exclusively to the railroad company. Beyond all question, the intention of Congress was to require the railroad company to perform the duty imposed upon it under the superintendence and subject to the control of the municipality. No one supposes that, if the railroad company foiled to perform its duty and permitted the spaces [355]*355occupied by the tracks to be in bad repair, and injury accrued therefrom to any one, the municipality would be relieved from liability.
It is scarcely, if at all, controverted on behalf of the defendant that the railroad company is subject to municipal regulation in this matter of paving as well as in all other matters that are proper subjects of municipal ordinance. We regard it as clear under the law, that, if the railroad company has failed to perform its duty properly, has improperly or defectively laid down its pavement, or has permitted that pavement to be out of repair, it is the duty of the municipality, under its paramount grant of power, to compel the performance, of the duty, and to require the pavement to be kept in good order and condition. And if the municipality may by regulation require and compel the railroad company to perform its duty in that regard, it certainty may, under the broad power of “entire control.' given to it, perform that duty itself, if the railroad company fails to do it, and charge the cost to the railroad company. This we understand, indeed, not to be denied by counsel for the defendant. The contention, as we understand it, is not that the municipality may not regulate the operations of the defendant, but that it may not change its duty ; and the argument then is, or would seem to be, that by requiring the defendant to change the pavement of its tracks so as to conform in character to the pavement of the remainder of the street, the municipality changes the duty of the railroad company and imposes a duty upon it different from that imposed by Congress. '
We are not convinced by this argument. A change of pavement is not a change of duty. It is common experience that, in the progress of civilization and refinement, municipal methods that were once satisfactory become wholly insufficient. The old style of cobble-stone pavement, which was once universal and a remarkable improvement over earth and mud, would now be regarded, at least in Washington, as intolerable. Municipalities should keep [356]*356pace with the civilization of the age and the progressive wants of their communities. It is no reason, because one class of pavement was once deemed entirely satisfactory, that it should not be replaced from time to time with others shown or supposed to have superior advantages. It is well-settled law that a municipality, having general control over its streets and avenues, may alter their grades at will, may replace one pavement with another as often as it deems expedient, and may impose successive impositions of taxes therefor. Smith v. Corp. of Washington, 20 How. 135; Gossler v. Georgetown, 6 Wheat. 593; Dillon on Mun. Corp., secs. 685, 686 and notes. Indeed, this right to alter the grades of the streets and to provide for successive repave-ments thereof is distinctly recognized and authorized by Congress in the act chartering the Metropolitan Railroad Company as proper to be exercised by the corporate authorities of the District of Columbia; for section 5 of that act, already cited, provides in express terms “ that nothing in this act shall prevent the Government at any timé at their option from altering, the grade or otherwise improving all avenues and streets occupied by said roads, or the city of Washington from so altering or improving such streets and avenues, and the sewerage thereof, as may be under their respective authority and control; and in such event.it shall be the duty of said company to change their said railroad so as to conform to such gradé and pavement.”
It is for the municipality then to determine what grades it will establish for the streets, what pavements it will lay, and what changes, if any, it will make from time to time in those grades and pavements ; and it is specifically made the duty of the railroad company to conform thereto. The power of the municipality does not extend merely to the portion of the highway not occupied by the railroad; for entire control over the whole area of the highway is given to it; and the conformity required from the railroad' company is necessarily conformity, to the and direction of order the municipality, subject of course to an appeal by the railroad com[357]*357pany to Congress for a limitation of what might prove to be municipal oppression, or to the courts for abuse of municipal discretion. In section 5 above cited conformity is-required from the railroad company, not only to any new grade which the municipality might establish, but likewise to any new pavement which the municipality might direct as proper for the street. The word pavement is there introduced for the first time in the act; but it is clear that it was included in the term improving previously used ; and there is no possibility of mistaking the intention and meaning of Congress in the matter. It cannot be that Congress proposed that, when the railroad company once put down a cobble-stone pavement, entirely satisfactory though it was at the time to every one, the status of the company in respect of that pavement was thereafter beyond municipal control, and no development of improved methods could operate to require the substitution therefor of any other- pavement. It was well said by the Supreme Court of Pennsylvania in the case of Philadelphia v. Ridge Ave. Railroad Co., 143 Pa. 444, 471, with reference to a similar condition of things occurring- in the city of Philadelphia:
“The duties specified in the‘(company’s) charter were imposed with reference to the changes and. improved methods of street paving which experience might sanction as superior to and more economical than old methods. In other words, the company is bound to keep pace with the progress of the age in which it continues to exercise its corporate functions. The city authorities have just as much right to require it to repave at its own expense with a new,. better, and more expensive kind of pavement as they have to cause other streets to be repaved in like manner at the public expense.”
It may be, that, under a duty merely to repair, or to keep in good order, no obligation would exist to repave with a new and different material. Chicago v. Sheldon, 9 Wall. 50; Baltimore v. Scharf, 54 Md. 499, 525; State v. Corrigan Con. St. Railway Co., 85 Mo. 263; although there are de[358]*358cisions to the contrary (Philadelphia v. City Pass. Railway Co., 169 Pa. St. 269; State v. Jacksonville St. Railway Co., 5 Am. & Eng. Railway Cases, 179); but no such limitation or construction can apply where absolute conformity to altered pavements is peremptorily required superimposed upon a duty to keep the spaces well paved.
We are constrained to conclude that it was within the statutory power and right of the Board of Public Works in this instance to require the defendant railroad company to substitute on the prescribed spaces, instead of the cobblestone pavement then in existence, the new pavement directed to be laid on the remainder of the highway; and upon the failure of the company so to do, after due notice to it, to put down the pavement itself by its own contractors and to charge the cost to the railroad company. See W. & G. Railroad Co. v. District of Columbia, 108 U. S. 522.
It would appear that, in fact, no notice was given to the railroad company and no opportunity afforded it to do the .work itself. But the element of notice is eliminated from our consideration in this case by the act of Congress and the consent of the railroad company to the provisions of that act, which requires us to assume “ that due and proper notice has been given to said company of all acts required in the premises.” As, therefore, it is to be assumed that notice was given to the company to do this work, and as it confessedly did not do the work, the right of the Board qf Public Works to do it at the cost of the company necessarily follows — provided that it was a work which could properly have been required from the company; and this we have determined.
Undoubtedly and beyond all question, the railroad company was right and the Board of Public Works was wrong in its judgment in regard to the relative merits and suitableness of the two pavements. But this was not the only error committed by the Board of Public Works in its brief, though phenomenal, career of extravagance. The public at large, greatly more than this railroad company, suffered from [359]*359the results of its recklessness, which necessitated its speedy abolition by the power which created it. Yet the railroad company cannot, any more than private citizens, be relieved from the burden of taxation entailed upon the entire community by its mistaken action. It is well settled law that a. municipality is not liable for an error of judgment on the part of its agents. Johnston v. District of Columbia, 118 U. S. 19; Dillon on Mun. Corp.,sec. 948, and notes, and cases there, cited. And from this it follows necessarily that its rights cannot be impaired by any such error of judgment. It does not cease to be responsible for the cost of a pavement because its agents have mistakenly selected one of inferior character. It does not lose its power of taxation therefor, because the worthlessness of the pavement happens afterwards to be demonstrated. The railroad company in this instance stands in no better position than the private citizen. The latter has contributed to the expense of these worthless pavements through the medium of general taxation ; citizens, whose property was located along the line of supposed improvement, have been compelled by special assessment to contribute more than their share of the general burden ; and the railroad company, which voluntarily by its charter assumed the duty of paving the portion of the highway occupied by its tracks and voluntarily assumed the risk, as we have held it did, of being subject to the direction of the municipality and of its agents in that regard, cannot stand in any better position. Its case appears to be a case of hardship; but it is not substantially different, or at all different in principle, from that of the rest of the community.
It is objected further, on the part of the defendant, that the streets involved in this controversy had never been authorized by the Legislative Assembly to be improved, and that therefore the proceedings of the Board of Public Works in regard to them were all null and void. There is force in this argument, and as an original proposition it might be admitted to be true. So far as this record shows, there was a taint of illegality in all the operations of the Board of [360]*360Public Works. But these Operations, so far as they could be the source of resultant right and resultant liability, Congress has so frequently recognized that without here entering into, detailed examination of the legislation on the subject, we must hold them to have been validated, to the same extent as though they had been authorized in the first instance. Mattingly v. District of Columbia, 97 U. S. 687.
We must conclude, therefore, that in respect of the items mentioned in schedule A, the District of Columbia is entitled to recover from the defendant, the Metropolitan Railroad Company, the amount thereof, namely, the sum of #37i5Si-6i.
5. And the result of the whole is, that we find to be due from the defendant, the Metropolitan Railroad Company, to the plaintiff; the. District of Columbia, the amount of schedule A, being.the sum of $37,551,61, and the amount of schedule B2, being the sum of $ 1,914.5 2, constituting the aggregate sum of $39,466.13; from which there is to be deducted the sum of $5,330.01, being the value of the cobble-stones belonging to the railroad company, conceded to have been taken and appropriated by the District of Columbia to its own use. The net remainder is the sum of thirty four thousand one hundred and thirty-six dollars and twelve ' cents ($3‡,136.12), for which sum, with interest thereon from November 27, 1880, the date of the institution of tins suit, judgment will be entered in favor of the plaintiff, the District of Columbia, with costs, as provided by the act of Congress referring the cause to this court. And it is so ordered.