If any person without lawful authority--
         (a) pulls down or wilfully damages any board or document set up or posted by the order of a railway administration on a railway or any rolling stock; or
         (b) obliterates or alters any letters or figures upon any such board or document or upon any rolling stock,
     he shall be punishable with imprisonment for a term which may extend to one month, or with fine which may extend to five hundred rupees, or with both.