The Council may transfer, during the current year, any part of an unencumbered balance of an appropriation to any other purpose or object for which the appropriation therefor, has proven insufficient, or may authorize a transfer of money to be made between items appropriated to the same office or department, except as follows:
   (a)   No transfer shall be made from any bond or note fund, except that the unencumbered or unexpended balance of such fund no longer needed for the purpose for which such fund was created, shall be transferred to the fund from which said bonds or notes are to be paid.
   (b)   No transfer shall be made of money raised or appropriated for the payment of any bond or note of the Municipality unless all indebtedness, interest and obligations, which can lawfully be paid from such money, have been paid.
   At the close of each fiscal year, the unencumbered balance of each appropriation other than the appropriations of bond and note funds, shall revert to the fund from which it was appropriated and shall be subject to future appropriation, except otherwise provided in the next paragraph of this section.
   A fund to be known as the Improvement Fund may be maintained in the Treasury into which Municipal moneys may be appropriated or allocated from time to time by action of Council, and which shall then become and remain separated and distinct from general funds.  Improvement Fund moneys may be advanced or expended from time to time by action of Council for public improvements not otherwise provided for.