§ 147. Deputy health officer. The health officer by the authority and under the direction of the commissioner of public safety may appoint a deputy, to hold office during his pleasure. He may, when authorized by the commissioner and subject to the approval of the board of estimate and apportionment, appoint such other assistants and employ such health and sanitary experts as may be required to carry into effect the powers, decisions, orders and directions vested in said commissioner and health officer by this chapter and otherwise by law. The compensation of such deputy, assistants and experts shall be fixed by the commissioner, subject to the approval of the board of estimate and apportionment.