The said treasurer shall keep a just and true account of the receipts and expenditures of all moneys which shall come into his hands by virtue of his office, in a book or books to be kept by him for that purpose, which books shall be open at all times for the inspection of the board of county commissioners or any member thereof, and to all county and state officers; and at a meeting in October of each year of the said board of commissioners, and at such other time as they may direct, he shall settle with them his accounts as treasurer, and for that purpose he shall exihibit to them his books, moneys, accounts, and all vouchers relating to the same, to be audited and allowed.