Where the appointment of the returning officer to act at the election of commissioners is not provided for by the special Act, the chairman of the commissioners shall be the returning officer; and if the commissioners are to be elected for wards, the said chairman shall act as the presiding officer at the election for the ward for which he was elected a commissioner, and he shall appoint some other commissioner for each of the other wards to be the presiding officer at the election for such ward, and in case of the death of any such presiding officer, or of his declining or becoming incapable to act, the commissioners shall appoint another of their body to be the presiding officer in the place of the person so dying or declining, or becoming incapable to act, and the clerk to the commissioners shall, two days at least before each election, by advertisement, placards, or otherwise, give public notice of every such appointment.