On the second Tuesday in October next, and on the same day every two years thereafter, it shall be lawful for the qualified voters in the several counties of this Commonwealth, to elect a suitable person to serve as county treasurer, who shall enter upon the duties of his office, on the first Monday in January next, after his election, and perform all the duties enjoined by law on the several county treasurers of this Commonwealth, until the first Monday in January, two years next after his induction into office as aforesaid.