In cases where stop cock boxes and street washers are set into the flagging or pavement of the sidewalk, the stones shall be neatly and accurately cut, and the top of the boxes set even with the surface of the pavement or flagging. In all other cases they shall be set flush with the surface of the sidewalk or lawn. If from any cause the stop cock box or other fixture is above or below the surface of the sidewalk or lawn, it must be brought to the surface of the same.