(b) That said system of accounts and rules and regulations therein contained shall, as to all public utilities now subject to the jurisdiction of the Commission and as to all present licensees, become effective on January 1, 1937, and as to public utilities and licensees which may hereafter become subject to the jurisdiction of the Commission, they shall become effective as of the date when such public utility becomes subject to the jurisdiction of the Commission or on the effective date of the license (a) That said system of accounts and said rules and regulations contained therein be and the same are hereby prescribed and promulgated as the system of accounts and rules and regulations of the Commission to be kept and observed by public utilities subject to the jurisdiction of the Commission and by licensees holding licenses issued by the Commission, to the extent and in the manner set forth therein The Federal Power Commission acting pursuant to authority granted by the Federal Power Act, particularly sections 301(a), 304(a), and 309, and paragraph (13) of section 3, section 4(b) thereof, and finding such action necessary and appropriate for carrying out the provisions of said act, hereby adopts the accompanying system of accounts entitled “Uniform System of Accounts Prescribed for Public Utilities and Licensees Subject to the Provisions of the Federal Power Act,” and the rules and regulations contained therein and It is hereby ordered: Prescribing a system of accounts for public utilities and licensees under the Federal Power Act.