Section 15
SEC. 15. At any time after forty years from the date of the approval of this Act, the Republic of the Philippines or any of the political subdivisions thereof to which the right may be assigned, may purchase, and the grantee shall sell thereto, all of his plant, poles, wires, buildings, real estate, and all other property used in the enjoyment of this franchise, at a valuation based in part upon the net earnings of the grantee and its true worth on the books, making the proper deduction for depreciation; in part on the cost of the actual reproduction of said property, less depreciation and, in part, on the original cost of said property, less depreciation, the valuation to determined after hearing by the Supreme Court of the Philippines, sitting as a board of directors, whose decision, by majority of the members thereof, shall be final.