Section 5
SEC. 5. In the event the Government may not have the necessary funds to be certified as available for any single contract out of the appropriation herein provided, authority is hereby granted to the contractor to finance from his own funds any single contract for any of said structures, and the appropriations authorized under Section one hereof shall be made available for the amortization of both principal and interest of any unpaid balance at a rate of interest not exceeding twelve per cent per annum: Provided, That no contract shall be amortized and paid for a period longer than twenty years.