No contract shall hereafter be made by the City Council or any committee or member thereof, and no expense shall be incurred by any of the officers or departments of the city whether the object of the expenditure shall have been ordered by the City Council or not, unless an appropriation shall have been previously made concerning such expense, provided that nothing herein contained shall prevent the City Council from ordering, by 2/3 vote, any improvement the necessity of which is caused by any casualty or accident happening after such appropriation is made. The City Council may by an aye and nay vote order the Mayor and Finance Committee to borrow a sufficient amount to provide for the expense necessary to be incurred in making improvements the necessity of which has arisen as is last above mentioned, for a space of time not exceeding the close of the next fiscal year, which sum and interest shall be added to the amount authorized to be raised in the next general tax levy and embraced therein.
(`79 Code, § 35.001)