The Council shall have the power to make investigations into City affairs and to inquire into the official conduct of any department, agency, office or employee of the City. For this purpose the Council shall have the power to administer oaths to subpoena witnesses and to compel the production of books, papers and other evidence material to the inquiry. The Council shall provide by ordinance penalties for contempt in failing or refusing to obey any such subpoena or to produce any such books, papers or other evidence, and shall have the power to punish any such contempt in the manner provided in the ordinance.