The Council may transfer any part of an unencumbered balance of an appropriation of any fund, to any purpose or object for which the appropriation for the current year has proved insufficient, or may authorize a transfer of moneys 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 unexpended balance of such fund no longer needed for the purpose for which said 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 moneys raised or appropriated for the payment of any bond or note of the Municipality, until all indebtedness, interest and other obligations which can lawfully be paid from such moneys have been paid.
At the close of each fiscal year the unencumbered balance of each appropriation, except appropriations to bond or note funds or any other trust or special fund which the Council by law or by this Charter shall be authorized to create, shall revert to the fund from which it was appropriated, and shall be subject to future appropriation.