With reference to the police department the following definition shall apply as used herein: The word patrolman shall mean and apply to all motorcycle officers, drivers of automobiles used by the police department, and all other members of the police department below the grade of sergeant but shall not include detectives. The word officer shall mean and apply to all members of the police department of the grade of sergeant, detective, captain, assistant chief of police, and chief of police. The words members of the police department shall mean and include all officers, patrolmen, and detectives, and wardens, if detailed to warden’s duty from the ranks of patrolman or officers. With reference to the fire department the following definitions shall apply as used herein: The words members of the fire department shall mean and include the chief of the fire department, assistant chiefs of the fire department, captains, lieutenants, engineers, assistant engineers, and firemen and all others who are regularly carried on the pay roll of the fire departments except hostlers and helpers; and in addition to those specifically named hereinbefore as members of the departments, such others as the board may find and designate to properly be such members, respectively.