On and after the first day of January, 1880, it shall be the duty of the councils of the cities of the first class to fix the salaries and number of clerks and employés of all persons who are paid their salaries by warrant or otherwise out of the city treasury, excepting only those officials who are elected by the people, or whose salaries are fixed and established as to amount by act of assembly of this commonwealth, or fixed by the courts by existing laws.
53 P.S. § 13402