Before June 1, 1915, the present Council shall divide the City into sixteen wards, not less than three of which shall be on the east side of the Maumee River. After each recurring Federal census, and within three months after the proclamation by the Secretary of State of the population of the cities of Ohio, the Council shall redivide the City into wards upon the basis of not less than ten thousand nor more than twenty thousand persons in each ward. But all wards formed by the Council shall be composed of contiguous and compact territory, as nearly equal in population as possible and bounded by natural boundaries or street lines. When territory is annexed to the City, the Council, by ordinance, shall declare it a part of the adjacent ward or wards. If the Council fails to make such subdivision into wards within the time herein required, the President of the Council shall notify the Director of Law, who shall make such subdivision within thirty days thereafter.