A fire reserve, hereinafter called “reserves,” is established as a voluntary organization composed of persons appointed by the fire chief, hereinafter called the “chief,” to serve gratuitously as a unit of the fire department and to assist members of the regular department in suppression of fires and other emergencies within the city under conditions which make it impracticable to furnish adequate fire protection by means of regular firefighters. (Prior code § 3.40.010)