Included in the term "public park" shall be all those lands, whether privately owned or not, when the same are in fact used as public playgrounds, except that nothing herein contained shall abridge the night of a person owning property to enter upon the same at will and to permit others to do likewise, to otherwise exercise dominion over the same to the fullest extent of his title and ownership. (Ord. 221 § 3, 1958)