Sec. 6. PAYMENTS BY MEMBERS. Commencing with the first day of the month after the expiration of ninety (90) days from the passage of this Act, each member of the Pension System shall pay monthly into the Pension System Fund not less than four per cent (4%) nor more than seven per cent (7%) of his statutory minimum and longevity pay. Subject to this limitation, the Pension Board shall set the amount that each member shall pay into said Pension System Fund. Said payments into the Pension System Fund shall be effected by the city deducting the amount to be contributed by each member of said Pension System from his wages earned. Said deduction shall be paid into the Pension System Fund by the city.