Section 79. All pensions which were payable under chapter five hundred and three of the acts of nineteen hundred and twelve or chapter six hundred and seventy-one of the acts of nineteen hundred and thirteen by any city or town to former employees of a fire or water district therein which accepted chapter three hundred and fifty-two of the acts of nineteen hundred and fourteen at the annual meeting of the district held next after the passage thereof, shall be paid by the district.