The bonds shall be payable in lawful money of the United States at the office of the treasurer and bear interest at a rate not exceeding 8 percent per annum, payable semiannually in like lawful money. The interest for the first year may be payable in one installment at the end of such year, or the interest for the period from the date of the bonds to a date not later than 30 days after the date the second installment of the first district taxes levied after the date of said bonds will become delinquent may be payable in one installment at the end of such period.