SHORT TAKES : Crosby, Stills and Nash Sound a Positive Note at Berlin Wall

Crosby, Stills and Nash, whose rock music roots reach back to the early years of the Berlin Wall, sang to several hundred chilly fans today in front of the Brandenburg Gate, telling them to keep chipping away at the wall.

Stephen Stills said the 20-minute performance with sidekicks David Crosby and Graham Nash was arranged on short notice, with help from the West Berlin police.

“We just showed up yesterday and said, ‘Hi, we’re here, we want to sing,’ ” Stills told his audience, which included longtime fans of the group, curious tourists gazing across the wall at the gate’s classical columns, as well as Berliners attracted by the music from the nearby snow-dusted Tiergarten park.

Crosby, Stills and Nash, survivors of various headline bands from the mid-1960s, are the latest to bring music to the celebration of East Germans’ new freedom to travel through the Berlin Wall, erected in 1961 to stem a flow of refugees to the West.

Cellist Mstislav Rostropovich and rocker Joe Cocker were among the musicians to perform near the wall on the first weekend after the Nov. 9 decision to lift travel restrictions.