Now as to the operator's hours of work and the provisions made for her comfort and welfare. Her hours are short, and the working time is broken by rest and lunch periods so that she does not suffer from fatigue. As telephone service must be given continuously, it is essential that the required number of operators be on duty at all hours of the day and night, but the operators are arranged in different shifts, or "tours," so that the hours of duty of anyone operator are well within "reasonable limits. No operator has more than an eight-hour day. As far as possible operators are assigned to "central offices convenient to their homes, and thus long trips to and from their work are avoided.