The City Council shall appoint, and may remove at its pleasure and appoint others in their stead, the following officers, none of whom shall be members of the City Council, viz: a Collector of Taxes, a Superintendent of Streets and Waterworks, a City Attorney, a Board of Fire Wardens, consisting of one Chief and a first and second Assistant Engineer, and such other officers not herein otherwise provided for as are required by law. The City Council may fill vacancies in elective City offices, including the Board of School Trustees, until the next annual meeting, unless a special City meeting for the purpose of filling such vacancy is sooner warned and held. The City Council may fill vacancies in appointive offices until the next annual meeting or during the pleasure of said Council.