Professor Emeritus Enoch Durbin did not set out to invent a better tennis racket when he took his complaint of tennis elbow to his family doctor, but he's learned that inspiration often takes root in unexpected soil.

"I like to play tennis,'' he said. "I asked the doctor what I should do. His answer was take up another sport, like playing bridge.''

Professor Durbin's inspiration was, to put it more mildly than he did himself, to reject the physician's advice and delve deeper into the mechanics of his problem. What specifically is it about striking a tennis ball with a racket that causes tennis elbow? Framing precise questions is the first step to inventing a better tennis racket, or anything else for that matter, Professor Durbin said.

The first task was to learn about tennis elbow, which as it turned out is an irritation of the upper arm muscles that has nothing to do with the elbow. The ailment is caused by the shock of the ball striking the racket and traveling up the arm. The solution is to hit the ball at the center of percussion on the racket, which results in pure rotation. The shock then flips the wrist, without harm, instead of roiling up the arm muscles.

Professor Durbin's research involved a good deal of whacking tennis balls dipped in red dye to determine where he actually struck the ball relative to the center of percussion. That led him eventually to elongate the racket, adding more string that made it lighter, which in turn got him thinking about strings. That ended up with him borrowing his wife's pressure cooker to shrink highly twisted nylon string, which created a racket that cups the ball, holding it longer, and giving spin and slice to players, such as himself, who had never had it.

The result is the Elbow Saver, a lighter, longer racket that, two or three patents later, is a modest commercial success.

Teaching rewarding

The market prospects of the Elbow Saver do not interest Professor Durbin half so much as teaching SEAS students the thought process that led him to invent his better racket and the many other patents he holds.

"These kids that Princeton brings in are spectacular. To the credit of the faculty, if they do it right, they don't get in the way. Nurture and get out,'' he said. "You are trying to get them to see.''

As Yogi Berra once noted, you can observe a lot just by looking. Professor Durbin encourages students to seek inventive projects close to home, as he did with his own aching arm. He counsels them to trust that with enough concentration and study the magic moment of seeing will flicker into light.

Professor Durbin's quest to get his students "seeing'' in the manner of inventors begins with a single, teasing question. "What do you want to do when you grow up?''

Translated, he asks students to think through their interests to find a problem they want to solve. A favorite successful example he cites is Sandra Shefelbine '97, a student who wanted nothing more than to talk with her grandmother.

Sandra, who is now working for her doctorate in mechanical engineering at Stanford University, recalled that she knew what she wanted to do for her senior thesis, but she asked Professor Durbin for guidance in getting it done.

"My grandmother provided the inspiration as I realized she was becoming hard of hearing,'' Sandra recalled. "She understood me when I was speaking directly to her, but had difficulty in group settings. And she did not want the trouble of fitting and adjusting an electrical hearing aid, but needed something to direct the sound.''

Results oriented

Professor Durbin recalled a brief conversation that led, ultimately, to Sandra designing a hearing aid that worked for her grandmother and earned her a Churchill Fellowship to study at Cambridge University.

"In about three or four minutes I learn that she loves her grandmother but her grandmother has some sort of hearing loss that keeps them from communicating,'' he said. "My total nurturing was asking, what happens to your hearing when you get older?''

Sandra's research revealed that as people age they tend to lose the ability to hear high frequencies, but the biggest practical loss was the decreasing ability to screen out background noise that masks spoken words.

"The background noise is crucial,'' said Professor Durbin.

With that sharpened focus Sandra set about designing a mechanical hearing aid that amplified low frequencies, which are the key to understanding speech, but used no electrical amplification.

"Professor Durbin encouraged me to examine many design options before locking in on a particular design,'' she said. "I learned that it is important in the design process to consider all the alternatives before finalizing a design.''

The final design, which used a plastic baseball cut in half for its primary material, allowed Sandra's grandmother to hear individual voices during a family dinner or similarly acoustically busy gatherings.

"The effect was phenomenal, and without any electronics,'' said Professor Durbin.

Sandra did not pursue a patent after discovering a similar device had already been patented though never brought to market. Nonetheless, her work, plus Professor Durbin's encouragement, led to her successful application for one of 10 annual Churchill Fellowships to study at Cambridge. Her master's thesis there was "Requirements Capture for Medical Device Design," which built on her work at SEAS.

"Professor Durbin was very supportive,'' she said. "He always came to my orchestra concerts. It impressed me that he took an interest in his students outside of academics.''

Engineering is a profession of precision, and invention is engineering on a quest. Sharp, focused questions that guide thorough research focused on a problem of personal interest are the tools for cultivating the inventive imaginations of SEAS students, said Professor Durbin.

"A key to inventing is seeing a thing that, after you've seen it, people will say it is obvious,'' he said. "Circumstances that have never occurred in quite the same way before lead us to see something for the first time in a way nobody else has ever quite seen it, but afterwards it seems obvious. And those are the best inventions of all.''

Photo by Frank Wojciechow

Playing in the big league

Mason Rocca '00 has signed on with a professional basketball team. Rocca, number 44, is a forward for the Trenton Shooting Stars, a member of the International Basketball League. Pictured here in a February game against the St. Louis Swarm, Rocca had a season high and game high of 11 rebounds and scored nine points. The Shooting Stars won. Rocca earned his B.S.E. in electrical engineering.