Just as construction crews were frantically completing work on refurbishing Trinity Church’s bell tower this week, they received help from an unexpected pair of hands.

Days before the church’s 12 new change bells will ring their inaugural chimes, the philanthropist Martin “Dill” Faulkes, whose donation made the project possible, emerged from the scaffolding wearing blue jeans and work gloves.

“Four of us installed the bells,” he said proudly. “It took about a week.”

The entire project has been several years in the making. Mr. Faulkes, a British entrepreneur who worked on Wall Street during the early 1980s, first contacted Trinity Church in Lower Manhattan in 2001 about installing change bells, which are rung according to a mathematical sequence, or “changes,”instead of adhering to a particular melody. Then came the attacks of September 11, and the idea was shelved for several years.

Mr. Faulkes, himself a change-ringer since age 12, persisted. A longtime supporter of science and educational charities, he wanted to give back to Manhattan, a city that introduced him to capitalization and philanthropy, he said.

Last year, he donated $1 million to refurbish the bell tower, retune the church’s 10 older chime bells, and install 12 new swing bells. On Friday, ringers from England will ring Trinity’s inaugural chime. Saturday, they will attempt a “peal,” a series of changes that takes some three hours to complete.

Change ringing dates back to the Middle Ages, and today’s techniques are similar to a practice refined during the 17th century. While change-ringing is popular in Britain, there are only about 450 members of the North American Guild of Change Ringers. At the historic Trinity Church, change-bells have not been rung since before World War II.

In fact, ringing is something of an unknown art in local circles. “I had a rope-handling lesson, and it was quite humbling,” the church’s vicar, the Reverend Canon Anne Mallonee, said. “You think you just pull the rope and the bell rings, but there’s a rhythm to it and you have to pay attention. It’s not as easy as it looks.”

She said, somewhat ironically, that the church leadership is not quite sure how loud the bells will sound when the installation is complete. “We know from the foundry that the decibel won’t be louder than our current bells,” she said, laughing. “We want to be good neighbors.”