Section 38. To meet the expense of acquiring land in fee under section thirty-five or for constructing buildings under section thirty-six, the county commissioners may borrow from time to time, upon the credit of the county, such sums as may be necessary, not exceeding in the aggregate in any one year the sum of ten thousand dollars, and may issue bonds or notes of the county therefor, which shall be payable in not more than five years from their respective dates. The expense of maintaining industrial farms as authorized under sections thirty-five, thirty-six and thirty-seven shall be provided for in accordance with section twenty-eight of chapter thirty-five. Bonds or notes issued under authority of this section shall bear on their face the words, County of Industrial Farm Loan, General Laws, Chapter 126, ? and, except as herein provided, shall be subject to chapter thirty-five. Such bonds or notes shall be signed by the treasurer of the county and countersigned by a majority of the county commissioners and shall not be sold for less than their par value. The county may sell the said securities at public or private sale and the proceeds shall be used only for such of the aforesaid purposes as are specified in the vote authorizing the loan.