Opinion of the Court. The present constitution of Kentucky, adopted in 1891, contains the following provisions: "§ 170. There shall be exempt from taxation public property used for public purposes. "§ 171. The General Assembly shall provide by law an annual tax, which, with other resources, shall be sufficient to defray the estimated expenses of the Commonwealth for each fiscal year. Taxes shall be levied and collected for public purposes only. They shall be uniform upon all property subject to taxation within the territorial limits of the authority levying the tax; and all taxes shall be levied and collected by general laws. "§ 172. All property, not exempted from taxation by this constitution, shall be assessed for taxation at its fair cash value, estimated at the price it would bring at a fair voluntary sale; and any officer, or other person authorized to assess values for taxation, who shall commit any wilful error in the performance of his duty, shall be deemed guilty of misfeasance, and upon conviction thereof shall forfeit his office, and be otherwise punished as may be provided by law.” By the Kentucky Statutes of 1894 it is provided : "§ 4020. All real and personal estate within this State, and all personal estate of persons residing in this State, and of all corporations organized under the laws of this State, whether the property be in or out of this State, including intangible property, which shall be considered and estimated in fixing the value of corporate franchises as hereinafter provided, shall be subject to taxation, unless the same be exempt from taxation by the constitution, and shall be assessed at its fair cash value, estimated at the price it would bring at a fair voluntary sale." "§ 4022. For the purposes of taxation, real estate shall include all lands within this State and improvements thereon; and personal estate shall include every other species and character of property that which is tangible as well as that which is intangible." "§ 4026. The following property is exempt from taxation: Public property used for public purposes. Opinion of the Court. This act repealed all acts and parts of acts in conflict with its provisions except the act of June 4, 1892, providing additional funds for the ordinary expenses of the state government, and the act amendatory thereof approved July 6, 1892. In the year 1895 certain lands acquired under the above act of May 1, 1886, and constituting a part of the Covington Water Works, were assessed for state and county taxation, pursuant to the statutes enacted after the passage of that act, and conformably as well to the constitution of Kentucky if that instrument did not exempt them from taxation. The taxes so assessed not having been paid, those lands after due notice were sold at public outcry by the sheriff, (who by law was the collector of state and county revenue,) and no other bidder appearing, the Commonwealth of Kentucky purchased them for $2187.24, the amount of the taxes, penalty, commission and cost of advertising. The present action was brought by the Commonwealth to recover possession of the property so purchased. The principal defence is that the provision in the act of May 1, 1886, that the reservoir or reservoirs, pumping house, machinery, pipes, mains and appurtenances, with the land upon which they are situated, "shall be and remain forever exempt from state, county and city taxes," constituted, in respect of the lands in question, a contract between the city of Covington and the Commonwealth of Kentucky, the obligation of which was impaired by the subsequent legislation to which reference has been made. Referring to section 170 of the present constitution of Kentucky declaring that "there shall be exempt from taxation public property used for public purposes," the Court of Appeals of Kentucky, in this case, said: "It was followed by necessary statutory enactments, which, however, could neither curtail nor enlarge exemption from taxation as prescribed by the constitution; and accordingly, in section 4020, Kentucky Statutes, adopted for the purpose of carrying out the provisions of section 170, is the identical language we have quoted. As it was manifestly intended by both the constitution and stat Opinion of the Court. ute to make subject to taxation all property not thereby in express terms exempted, it results that, unless the water-works property of the city of Covington be, in the language or meaning of section 170, 'public property used for public purposes,' it must be held, like similar property in other cities, subject to taxation, and the special act of May 1, 1886, stands repealed. Assuming, as a reasonable and beneficial rule of construction requires us to do, that the phrase 'for public purposes' was intended to be construed and understood according to previous judicial interpretation and usage, there can be no doubt of the proper meaning and application of it, for in the cases cited and others, where the question of subjecting particular property of cities to taxation arose, the words 'for public purposes' had been held by this court to mean in that connection the same as the words 'for governmental purposes,' and so property used by a city for public or governmental purposes was held to be exempt, while that adapted and used for profit or convenience of the citizens, individually or collectively, was held to be subject to taxation; and, recognizing and applying that distinction, water-works property of a city has been invariably treated by this court as belonging to the latter class, and consequently subject to the state and county taxation. In our opinion, the property in question is under the constitution subject to taxation, and the statute enacted in pursuance of it operated to repeal the special act of May 1, 1886." However much we may doubt the soundness of any interpretation of the state constitution implying that lands and buildings are not public property used for public purposes when owned and used under legislative authority by a municipal corporation one of the instrumentalities or agencies of the State, for the purpose, and only for the purpose, of supplying that corporation and its people with water, and when the net revenue from such property must be applied in the improvement of public ways, we must assume, in conformity with the judgment of the highest court of Kentucky, that section 170 of the constitution of that Commonwealth cannot be construed as exempting the lands in question from taxation. In other words, we must assume that the phrase "pub Opinion of the Court. lic purposes" in that section means "governmental purposes," and that the property here taxed is not held by the city of Covington for such purposes but only for the "profit or convenience" of its inhabitants and is liable to taxation at the will of the legislature unless at the time of the adoption of the constitution of Kentucky it was exempt from taxation in virtue of some contract the obligation of which is protected by the Constitution of the United States. The fundamental question in the case then is whether at the time of the adoption of that constitution the city of Covington had, in respect of the lands in question, any contract with the State the obligation of which could not be impaired by any subsequent statute or by the present constitution of Kentucky adopted in 1891. If the exemption found in the act of 1886 was such a contract, then it could not be affected by that constitution any more than by a legislative enact ment. We are of opinion that the exemption from taxation embodied in that act did not tie the hands of the Commonwealth of Kentucky so that it could not, by legislation, withdraw such exemption and subject the property in question to taxation. The act of 1886 was passed subject to the provision in a general statute of Kentucky, above referred to, that all statutes "shall be subject to amendment or repeal at the will of the legislature, unless a contrary intent be therein plainly expressed." If that act in any sense constituted a contract between the city and the Commonwealth, the reservation in an existing general statute of the right to amend or repeal it was itself a part of that contract. Griffin v. Kentucky Ins. Co., 3 Bush, 592. The city accepted the act of 1886 and acquired under it the property taxed subject to that reservation. There was in the act no "plainly expressed" intent never to amend or to repeal it. It is true that the legislature said that the reservoirs, machinery, pipes, mains and appurtenances, with the land upon which they were situated, should be forever exempt from state, county and city taxes. But such a provision falls short of a plain expression by the legislature that at no time would it exercise the reserved power of Opinion of the Court. amending or repealing the act under which the property was acquired. The utmost that can be said is that it may be inferred from the terms in which the exemption was declared that the legislature had no purpose at the time the act of 1886 was passed to withdraw the exemption from taxation; not that the power reserved would never be exerted, so far as taxation was concerned, if in the judgment of the legislature the public interests required that to be done. The power expressly reserved to amend or repeal a statute should not be frittered away by any construction of subsequent statutes based upon mere inference. Before a statute-particularly one relating to taxation - should be held to be irrepealable, or not subject to amendment, an intent not to repeal or amend must be so directly and unmistakably expressed as to leave no room for doubt; otherwise, the intent is not plainly expressed. It is not so expressed when the existence of the intent arises only from inference or conjecture. The views we have expressed as to the power of the legislature under a reservation made by general statute of the right to amend or repeal are supported by many adjudged cases. Tomlinson v. Jessup, 15 Wall. 454, 458; Railroad Co. v. Maine, 96 U. S. 499, 510; Railroad Co. v. Georgia, 98 U. S. 359, 365; Hoge v. Railroad Co., 99 U. S. 348, 353; Sinking Fund cases, 99 U. S. 700, 720; Greenwood v. Freight Co., 105 U. S. 13, 21; Close v. Glenwood Cemetery, 107 U. S. 466, 476 ; Spring Valley Water Works Co. v. Schottler, 110 U. S. 347, 352; Louisville Gas Co. v. Citizens Gas Co., 115 U. S. 683, 696; Gibbs v. Consolidated Gas Co., 130 U. S. 396, 408; Sioux City Street Railway v. Sioux City, 138 U. S. 98, 108; Louisville Water Co. v. Clark, 143 U. S. 1, 12. In Tomlinson v. Jessup, above cited, referring to the reserved power to amend and repeal, this court said: "The object of the reservation, and of similar reservations in other charters, is to prevent a grant of corporate rights and privileges in a form which will preclude legislative interference with their exercise if the public interest should at any time require such interference. It is a provision intended to preserve to the State control over its contract with the corporators, which, without that provi |