§ 93. When police matrons to reside at station houses. When only one police matron is attached to a police station, she shall reside there, or within a reasonable distance therefrom, and shall hold herself in readiness to respond to any call therefrom at any hour of the day or night, and each matron shall, during such hours as may be fixed by the head of the police department, remain in such station and hold herself in readiness to respond to any call therefrom. So long as any woman is detained or held under arrest in a police station to which a police matron is attached, it shall be the duty of such matron to remain constantly thereat, ready for service; or if there be more than one matron attached to such station, then one of them shall be constantly ready for service. A police matron shall, subject to the officer in charge of such station house, have the immediate care and charge of all women held under arrest in the station to which she is attached, and she may at any time call upon the officer in charge of such station for assistance. She shall be subject to the authority of the board of police, or if there be no such board, then to the chief of police in the city where she may be appointed, and to the rules prescribed by such authority, but at a station where she may be on duty she shall be subject only to the authority of the officer in charge thereof.