The City Council, City Clerk, and the justices of the peace residing in the City shall constitute the Board of Civil Authority for the City, and, in conjunction with the listers, shall constitute a Board for the Abatement of Taxes, and shall be governed by the general laws of the State in respect to the abatement of taxes. The Board of Civil Authority shall perform all the duties imposed by law upon the board of civil authority of towns, except as hereinbefore provided. All meetings of the Board of Civil Authority shall, on application, be appointed and notified by the Mayor in the manner provided by law for appointing and notifying the meetings of the board of civil authority in towns. The compensation of all officers, servants, and employees of the City shall be fixed by the City Council, except as herein otherwise provided.