The benefits conferred by this act shall apply to all persons employed in any capacity by or holding positions in the cities included in its provisions, or paid out of the treasury thereof, as aforesaid: Provided, That this act shall not apply to employés of such departments, bureaus, or offices as are now protected by pension authorized by the laws of this State, and in force at the time of the passage of this act.
53 P.S. § 13443