Any accruing revenue of the City not appropriated under an appropriation ordinance, and any balance at any time remaining after the purpose of the appropriation shall have been satisfied or abandoned, may from time to time be appropriated by the Council to such uses as will not conflict with any use for which specifically such revenue accrued. No money shall be drawn from the treasury of the City, nor shall any obligation for the expenditure of money be incurred, except pursuant to appropriations made by the Council, and whenever an appropriation is so made the Clerk of Council shall forthwith give notice to the Director of Finance. At the end of each fiscal year all unexpended balances of appropriations shall revert to the respective funds from which the same were appropriated and shall then be subject to future appropriation; but appropriations may be made in furtherance of improvements or other projects of the City which will not be completed within the current year. Money appropriated as hereinabove provided shall not be used for purposes other than those designated in the appropriation ordinance without authority from Council.