Each parking meter shall be so designed and constructed as to display a signal showing lawful parking following a deposit of coins of the United States therein during a period of time conforming to the parking limit now or hereafter provided for the part of the street upon which such a meter is placed. Each meter shall bear a sign or legend setting forth the time limit of parking, which sign or legend may be in lieu of any other vehicles in the adjacent parts of the street. Each such meter shall also be so designed and constructed that upon the expiration of such parking limit, it will indicate by automatic operation of a visual signal that the lawful parking period has expired.