The polls shall be opened at eight o’clock in the morning and kept open until six o’clock in the afternoon of the same day. The election judges shall choose one of their number to be chairman. The chairman may appoint judges and clerks to fill vacancies occurring during the progress of the election. Any election judge may administer or certify any oath required to be administered during the progress of the election. The election judges may decide upon the qualifications of electors and shall make certificates respecting any matter concerning the election.