It is unlawful for any person to park a motor vehicle upon any private property, or upon property used for private parking purposes, without the consent of the owner of said property, the person entitled to the possession thereof for the time being, or the authorized agent of either, provided that signs specifying conditions under which parking is permitted shall have been posted at all entrances to such property. Such signs shall be approved both as to wording and posting by the Police Department. (Ord. 2829-NS § 4, 1947)