High in the Bridges Hall of Music, behind the massive facade of dark mahogany and gleaming lead and tin of the new organ built by the firm of C.B. Fisk, Kenneth Wolfe pads across a catwalk and slips into a small, shadowed cavity amid a thousand silvery pipes. He crouches, listening.

A sharp whistle ascends to higher and higher tones until the sound seems to flee the hall altogether. Wolfe is concentrating on one particular pipe, the size of a pea shooter.

"Let's check Able sharp 3 on the four-foot," he tells his assistant, William Finch, seated at the keyboard a level below, in front of the organ's facade. The whistle sounds again, and when it stops, Wolfe reaches out with a long wand and gently taps a metal sleeve at the top of the little pipe. The adjustment is minute. If the sleeve goes up, the sound gets flatter; down, and it gets sharper.

Wolfe retreats along the catwalk to record the change in detail in a log book. He picks up an electronic device that measures pitch and watches the LED numbers flash like a pinball bonus score as Finch works several of the organ's keys and knobs. "Charlie sharp 2 OK, let's work up from there," Wolfe says. Their pace is methodical: Listen, listen, listen, tweak. Listen, listen, listen, tweak.

The organ is a marriage of art and physics. The late Charles Fisk, founder of the Gloucester, Mass., company, was a physicist who worked on the Manhattan Project. The complex behavior of sound waves and air in confined spaces has everything to do with how the organ sounds. While Wolfe and Finch work, a monitor silently traces the temperature and humidity near the pipes. If Wolfe removes a pipe, adjusts it and replaces it, he must wait until the pipe cools from the heat of his hands before checking the sound.

"This tends to be a warm room acoustically," Wolfe says of Little Bridges, as he carves a sliver of metal from a pipe. "It tends to accentuate the high harmonics, whereas the low ones are not similarly encouraged."

By voicing each pipe, the organ's sound can be adjusted to fit the hall. Wolfe works with an array of tools that look like medieval dental instruments, including small angular hammers, a nicking device, a chisel, a file, scissors and small spatulas ordinarily used by sculptors for modeling clay. He can tailor a pipe in many ways. Some have small ears or lips or tiny sawtooth notches at the slot where the wind flows out. Some have metal sleeves that can be shortened or lengthened. The organ's largest pipes are made of wood and have cutouts that can be covered to varying degrees. Wolfe and Finch work with the organ's flue pipes; another voicing team will move in later to adjust the reeds.

There are 3,519 pipes in the instrument, from less than half an inch to 32 feet long, and each one must be tuned for pitch and then adjusted for timbre. The voicing began in early summer and is expected to be finished around February. Wolfe is just one of a team of voicers from C.B. Fisk Inc., which has built a reputation as a superior crafter of organs that use a traditional mechanical key action. Although tracker organs are expensive to build, there has been a revival of interest in them for a number of reasons, including their great longevity, the player's enhanced control over the instrument's sound, and the ability to authentically render works by the great composers of the past.

The new instrument, like many constructed by Fisk, it is considered eclectic, drawing from the work of 19th-century French organ builder Aristide Cavaillé-Coll and from German organ-making traditions. It includes three manuals, or keyboards, and 66 ranks of pipes in all. (A rank is a tuned set of pipes of the same type and with a cohesive tonal quality.) The case, of Honduran mahogany, includes angelic figures in the central portion that were hand-carved by Morgan Faulds Pike of the Fisk company. The keys are of cow bone, with sharps of ebony, and the stop knobs are of cocobolo, an exotic tropical hardwood that is said to be so dense it will not float in water. A 3.5-horsepower electric blower, isolated behind a newly built cement-block wall to the rear of the organ, supplies the wind that passes through the pipes to make music. The organ weighs nearly 40,000 pounds, and when the voicing is finished, will be the product of more than 30,000 worker-hours of labor.

William Peterson, the Harry S. and Madge Rice Thatcher Professor of Music, College organist, and chair of the Pomona Music Department, has been involved in the organ project from the start. "It's very exciting to see an instrument of this quality being completed in Bridges Hall," he says. "The organ is beautifully designed to harmonize with its distinguished architectural surroundings." He added that he believes the organ, which was funded by deferred gifts from the late John '22 and Eugene Hill '26 of Upton, California, will take its place as one of the premier instruments in the state.

The Fisk company assigns composition numbers to the instruments it builds, and Pomona's is Opus 117. Many of Fisk's organs have been constructed for academic settings. Opus 116 was installed last year at Oberlin College in Oberlin, Ohio, and Opus 118 is a smaller practice organ at Rice University in Houston. But for those whose labor goes into it, each completed instrument is more than a number. They consider their practice of the centuries-old craft of building tracker organs to entail at least as much art as science.

David C. Pike, executive vice president and tonal director at Fisk, has overseen the organ's assembly and voicing. During the lengthy process of design, construction, assembly at the site, and especially the voicing, a feeling of connectedness develops between the workers and the organ, according to Pike.

"You've invested so much of yourself in the way the organ sounds," he says. "It's not that you feel proprietary about it, but you feel as if 'There's a lot of me in there.' So you become very close to these instruments; they're like children in a way."

--Michael Balchunas