Opinion by

This bill was filed for the purpose of having the assessment upon which the special tax was levied, declared illegal and void, and to restrain the defendants from proceeding in any manner to collect the tax in question. Equity has power in a proper case to restrain the collection of a tax, but it is a power that should be cautiously exercised, because as a general rule there is an edequate remedy at law. Equity will only intervene in such a case where there is either want of power to tax or ,a disregard of imperative constitutional requirements: Banger’s App., 109 Pa. 79; Gas Company v. Elk County, 168 Pa. 401. In the present case the taxing authorities had power to make the assessment and levy the special tax, and the irregularities complained of can all be corrected on appeal as provided by law, without the intervention of a court of equity. Under all the facts this court does not feel warranted in reversing the decree entered by the learned court below and declaring the assessment illegal and absolutely void. We base our conclusion on the ground that appellant has an adequate remedy at law and that this remedy should be pursued.

This decision must not be understood as an adjudication of the validity of the assessment, nor as an expression of approval of the method adopted by the Board for the Assessment and Revision of Taxes under the Act of 1905. What we do decide is that every question presented for our consideration in the case at bar, can be raised on appeal from the revised assessment under the law. There being an adequate remedy at law, a court of equity should be very slow to extend its restraining arm when by so doing the entire assessment would be stricken down. We assume that appeals are pending, and that the learned court below will have the opportunity of passing upon the merits of the questions raised here when the *518facts are presented on the law side of the court. In this connection it may be proper to remark that all parties concerned should approach the solution of the questions involved in a spirit of equity and fairness, keeping in mind the rules applicable to such controversies as laid down in several recent cases. The law is as well settled as it can be and nothing of value can be added to what has already been said as to the legal and proper method of making assessments. The law requires that the valuation of real estate for the purpose of taxation shall be determined upon the basis of market value, or rather actual value, limited and defined by market value. What the law requires cannot be disregarded no matter how desirable some method not authorized might prove to be: Pennsylvania Stave Company’s App., 236 Pa. 97. The proper method of making such assessments was very fully discussed in Lehigh & Wilkes-Barre Coal Company’s Assessment, 225 Pa. 272; Philadelphia & Reading Coal and Iron Company v. County Commissioners, 229 Pa. 460; and in several other recent cases. With these cases as a guide there should be no difficulty in adopting the proper method of ascertaining the taxable value. Scientific formulas, arithmetical deductions and mental contemplations, have small value in making assessments under our practical system of taxation. The market value of the separate tracts at public sale, after due notice, is the legal basis recognized by our statutes of determining the assessable value of real estate, and until the legislature changes this method, it is binding not only upon the taxing authorities but upon the courts as well. Nothing contained in the Act of 1905, applicable to Luzerne County, changes the basis of determining assessable value. Under this act the subordinate assessors make the assessments and valuations, and it is made the duty of the board of assessment to “examine and revise the said valuation increasing and decreasing the same as in their judgment may seem to be proper or adding thereto such property or subjects of taxation as *519may have been, omitted.” It will thus be seen that by the express terms of the act the duties of this board are limited to an examination and revision of the valuations returned by the subordinate assessors increasing or decreasing the same as in their judgment may seem proper. Beyond this the board of assessment cannot go except to add taxable property that may have been omitted by the subordinate assessors. The act is too plain to be misunderstood and there should be no difficulty in determining what the board may and may not do. It should be the effort of all parties concerned to fix the valuations upon a legal basis, and when this is done, there will be no occasion for further litigation. '

Decree affirmed at cost of appellant.