It shall be the further duty of the board, when necessary, to provide for the valuation and assessment of all subjects of taxation which may hereafter be made taxable by the county, or any city or other municipal subdivision of the Commonwealth located in or coterminous in its boundaries with the county, to prescribe the duties of the assessors appointed by it in connection with such valuation and assessment, to supervise and revise such assessments, and to give such notice as the board shall consider reasonable of such assessments and of the time for appeal therefrom.
72 P.S. § 5341.12