The Secretary of Transportation is authorized to appoint an administrative assistant and billboard clerk of outdoor advertising, and such assistants, clerical and otherwise as may be necessary, to prescribe the duties of the administrative assistant and billboard clerk, and, with the approval and consent of the Governor, to prescribe the salary for the administrative assistant. Said billboard clerk and such other assistants, clerical and otherwise, shall be included in and subject to the requirements of the classification and compensation plan of the personnel system authorized in 3 V.S.A. § 310. (Amended 1959, No. 238, § 1.)