“Public Library Employes’ Pension Act”: “An Act to provide for the formation and disbursement of a public library employes’ pension fund in cities having a population exceeding 500,000 inhabitants,” approved May 12, 1905, as amended, and as continued in, or superseded by the “Illinois Pension Code,” approved March 18, 1963, under Article 19, Division 2, Secs. 19-201 to 19-220, both inclusive.