Section 8. Those eligible to membership in the fund shall be:
(1) All uniformed employes of the bureau of fire, including the commanding officer and the chief of the bureau.
(2) All substitute uniformed employes of the bureau of fire.
(3) All persons who are at present members of the existing fund in such city. Employes of the bureaus of electricity and building inspection in such city who have entered such service since the first day of July, one thousand nine hundred and eighteen, shall not be eligible to be members of such fund.