53 Pa. Stat. § 23659
Any beneficiary under said fund shall, upon payment into the fund of the sum of two hundred dollars ($200), with accrued simple interest at three per cent (3%) per annum from the first day of August, one thousand nine hundred fifty-three, until the date it is paid, if paid after the fifteenth day of August, one thousand nine hundred fifty-three, but with no interest, if paid on or before the first day of August, one thousand nine hundred fifty-three, be entitled to receive from the fund annually and for life, in addition to his regular pension, determined in amount as of the date of his withdrawing from service in the city, an additional annuity, pro-rated on a monthly basis, as a one-twelfth addition to the monthly payments due on his regular pension, sufficient in amount that the total monthly payments received by him for regular pension and additional annuity combined shall equal the amount of the regular pension which he would have been entitled to receive if he had withdrawn from service in the city on and as of the first day of August, one thousand nine hundred fifty-three. Such additional annuity payments shall begin on the date on which the regular monthly pension payment is next due, after such contribution and interest have been paid.
53 P.S. § 23659