§ 76. Annual appropriations. When the common council shall have adopted the final estimate of the board of estimate and apportionment or said estimate as amended by it, the same shall be entered at large in its minutes and become a part of its proceedings. The several sums estimated for expenditures therein shall be and become appropriated in the amounts and for the several departments, offices and purposes as therein specified for the said fiscal year. The several sums therein enumerated as estimated revenues and the moneys necessary to be raised by tax in addition thereto to pay the expenses of conducting the business of the city and for the purposes contemplated by this chapter and otherwise by law, shall be and become applicable in the amounts therein named for the purposes of meeting said appropriations. In case the revenues received by the city exceed the amount of such estimated revenues named in said annual estimate, or in case there remain any unexpended balances of appropriations made for the support of the city government or for any other purpose, then such surplus revenues or such unexpended balances shall, except as otherwise provided by law, remain upon deposit and be included as a part of the estimated revenues for the succeeding year. When any moneys or revenues are received by any officer, board or department of the city, from any source other than by municipal tax, which are not otherwise appropriated, such moneys or revenues may be used and applied toward and in addition to the funds appropriated, as aforesaid, in such manner as in the judgment of the board of estimate and apportionment may be most beneficial to the city.