“Tomorrow, thanks to a Florida record collector and a serendipitous turn of events, that song — believed to be the earliest known recording featuring members of the BSO — will be played on the radio for the first time. After WGBH found out about it earlier this week, the station included “The Kerry Dance” as part of its Sunday broadcast, which takes place exactly 125 years, to the day, after the BSO’s first concert in 1881.”