Last week the musical director for the Mark Morris Dance Group, Colin Fowler, was away on bonding leave, so I filled in and played a rep show in Urbana.

One of the great Mark Morris dances is Grand Duo, set to a score of the same name by Lou Harrison. It was an early success for Mark and has remained a definitive crowd-pleaser. Reportedly the Urbana hit was the 484th MMDG performance of Grand Duo. (I played almost one hundred of those gigs myself during my time as MMDG music director in the late ’90s.)

The staff of MMDG musicians always includes great violinists, for the violin part to Grand Duo is fearsome and relentless. Last week it was Georgy Valtchev, a serious virtuoso with a wonderful sonority. However, the piano part is not as hard as it sounds, for some of the fire and brimstone is provided by a technology invented by the composer: the famous Lou Harrison octave bar.

A brief excerpt of me practicing the last movement, “Polka,” with the bar:

The key signature is unusual, a synthetic scale in F-sharp. There are no accidentals in “Polka,” for the full 5 minute piece is in one mode. (The first time one reads the score this key signature is a bit challenging.)

The first page posed with the bar:

The page with bar action heard in excerpt above:

There are several Lou Harrison pieces that use the bar. When I interviewed Keith Jarrett, he complained about the technology for the commissioned piano concerto.

I was having a bit of shoulder piano trouble when he wrote me the Piano Concerto, so I asked him not to write anything percussive. Then he turns around and gives me the “Stampede” movement, which is not just banging with the octave bar but putting it down and picking it up again. He said, “Don’t get muscle-bound.”

At the 2000 Kennedy Center Honors, Mikhail Baryshnikov requested “Polka” from Mark Morris and MMDG. Lo-fi video exists on YouTube. About twelve minutes in, I join violinist Jacqui Carrasco and the spectacular dancers. The other honorees were Angela Lansbury, Clint Eastwood, Placido Domingo, and Chuck Berry; the audience was full of other celebs including the Clintons. Herbie Hancock was there, and he asked to see the octave bar afterwards.