Musicians are eager to perform at the Dan Harpole Cistern, which is nearly 200 feet in diameter and 14 feet deep, giving it a 45-second reverberation time. By comparison, Benaroya Hall is about 4 seconds. The cistern is at Fort Worden State Park in Port Townsend.

By R.M. CAMPBELL

Summer often is full of unusual happenings, but it would be hard to rival tonight’s performance at Fort Worden State Park of John Cage’s “Atlas eclipticalis” at the bottom of the Dan Harpole Cistern by trombonist Stuart Dempster, no stranger to various musical wonders, and assorted colleagues.

A leftover of the park’s military days, the cistern, on the upper hill at Fort Worden, is nearly 200 feet in diameter and 14 feet deep. It was built as a water supply system. For reasons of safety it is entirely covered except for a trap door that allows people, mostly musicians eager to perform or record, to enter the space. One of its principal attractions to musicians is the extremely long reverberation time — about 45 seconds.

“It’s a big echo chamber,” said Dempster.

By comparison, Benaroya Hall is only about four seconds, St. James Cathedral six seconds and St. Mark’s Cathedral a little less. Grace Cathedral in San Francisco, Dempster said, is about 10 seconds.

Since only performing musicians will be in the cistern, loudspeakers will take the sound up to the audience seated on the grass above.

Dempster, who was on the University of Washington music faculty for 30 years, is not only familiar with Cage’s music, he also is an old hand with the cistern’s novel acoustical properties and ambience. While concerts in the space may be relatively rare, recordings are not.

His first recording there was with Pauline Oliveros, once a strong presence in the Seattle new music scene as a composer and performer and member of the UW and Cornish College faculties. Other recordings followed, including Cage’s music.

“The cistern is like an instrument you have to learn how to play,” Dempster said. “You whisper along the wall and your voice can be heard 186 feet away. But if you talk loudly, nothing is understood.”

Cage’s “Atlas eclipticalis” was commissioned by the Montreal Festival Society in 1961. It reached New York three years later when Leonard Bernstein and the New York Philharmonic did a performance at Lincoln Center. Microphones were attached to each instrument, the sounds of which were then channeled into six speakers placed throughout the hall. Many in the audience left during the performance. In subsequent concerts, orchestra musicians rebelled against the composer and the piece.

The work itself was inspired by a kind of celestial atlas published in 1958 by Czech astronomer Antonin Becvar. It is scored, according to the New Grove Dictionary of American Music, for “any ensemble from 86 instruments.”

There will not be 86 musicians in the cistern for tonight’s performance. There will be Dempster playing the trombone, conch shell and “assorted musical mayhem,” along with a handful of colleagues: Matt Kocmieroski, percussion; Walter Gray, cello; Seth Krimsky, bassoon.

Because Cage is an iconoclast and a revolutionary, such a disparity is not earth shattering — it comes with the territory. Throughout his long, fruitful life, Cage was always doing the unexpected, improvising and exploring the world around him. Rules either were simply discarded or rewritten. Chance was an important element.

“He composed for every imaginable kind of instrument,” according to his 1992 obituary in The New York Times, “from standard orchestral strings to ‘prepared’ pianos (which originated at Cornish). … He wrote electronic and tape works, and works that involved only spoken texts. His often impish scoring, in fact, might include radios, toys, the sounds of water being sipped or vegetables being chopped. … And one of his most famous and provocative pieces, ‘4’33’,’ is 4 minutes and 33 seconds of silence, divided into three movements. Indeed, Mr. Cage considered virtually every kind of sound potentially musical.”

Arnold Schoenberg, with whom Cage studied in California before coming to Seattle, called him “not a composer but an inventor of genius.”

Dempster said there often is flexibility to Cage’s music, and the “Atlas,” one of his more performed works, is no exception.

“I did it a few times in the 1960s with friends at the Zen Center in San Francisco, and it has been done at Cornish. Matt was hoping we could record this version.”

The trombonist has spent nearly a lifetime in the world of avant-garde art. He grew up in Berkeley, Calif., and attended San Francisco State University. Quickly he found a home in avant-garde circles, an association that continues today. It was that interest that propelled his

move in the late ’60s to Seattle, where he quickly became an integral part of the musical life of the city.

He played in traditional ensembles and ventured far beyond as well, experimenting with performances in unusual places and with a huge variety of sounds — some from the trombone and some from related instruments. Behind his considerable experimentation was a highly sophisticated technique and musical sensibility. He provided an informed and intelligent, often evocative, taste of contemporary music.