I experienced the same break Bill mentioned when we heard Karel Ancerl
conduct the Boston Symphony in "Ma Vlast" at Tanglewood in the late 60s.
The timing was fortuitous, because a thunderstorm struck right in the
middle of the "Moldau," as if on cue, and the intermission helped everyone
clean up and recover from the mini flash flood that passed through the
shed.

That evening ranks as my al fresco highlight at Tanglewood, followed by
the night Sir Colin Davis fought off a king-sized moth while conducting
Wagner's "Flying Dutchman" prelude.  With his coiffure and baton technique,
he made sure the bug never had a chance.

Dick Claeys