At the end of each fiscal year, the Council shall require the income and expenditures of each department and office of the City to be audited by one or more certified public accountants, who are not connected with the department to be audited. The accountants shall make their report directly to the Council and send copies to the Mayor and Controller. The Council shall determine the extent of the audit as to each of the departments, and may provide for the taking of the audit by resolution.