§ 74. Determination of positions and salaries. The board of estimate and apportionment, except as otherwise provided by law, shall have authority to fix the salaries or compensation, and determine the positions and numbers of all city officers and employees, of each office, board and department, but the salary or compensation of every officer and employee shall be thus fixed before his election or appointment, except in the first instance after the city shall have become a city of the second class and subject to the provisions of this chapter.