DUBLIN — Mícheál Ó Mainnín always wondered whether his grandfather had been telling the truth.

When Mr. Ó Mainnín was growing up on the Dingle Peninsula in County Kerry, Ireland, there was no radio or television to pass the time, he said, so people would tell stories. His grandfather had many, but he told one more than others.

In the mid-1920s, an American visited Dingle to study birds and collect specimens. Sometimes Mr. Ó Mainnín’s grandfather would bring the man — his name was Benjamin Gault, though the locals called him “Kaerty” — in his fishing boat to the nearby Blasket Islands. Kaerty always had a hand-cranked camera with him. One day, as he was filming Mr. Ó Mainnín’s grandfather and his friends, the grandfather stuck a pipe in his dog’s mouth as a joke.

“It was a very far-out story,” Mr. Ó Mainnín, 55, a farmer and fisherman in Dingle, said. “You would never think that it was true.”

Long after Mr. Ó Mainnín’s grandfather, also named Mícheál Ó Mainnín, died in 1981, the family wondered whether any of the film shot by the visiting American still existed.

Mr. Ó Mainnín’s curiosity ultimately led to the discovery of a collection of silent film reels depicting life in 1920s Ireland — police officers directing traffic in Cork City, horse-drawn carts piled high with wicker lobster pots, people attending horse races and Mass — all shot in 1925 and 1926, in the early years of Irish independence from Britain.

Footage of Ireland from that time — a period when memories of the First World War were still fresh, and Ireland was recovering from its own civil war — is incredibly rare. Most of the film that does exist is newsreel footage of major events, according to Manus McManus, the film collections and acquisitions manager for the Irish Film Institute.

“This stands out as quite unique in the sense of essentially recording the ordinary daily lives of people,” Kevin Rockett, a retired professor of Film Studies at Trinity College Dublin, said. “There’s lots of footage of the war, so that was what people would be most familiar with.”

Mr. Ó Mainnín started his search in 2011 with little to go on beyond the American’s name, but he quickly found out that Mr. Gault was an ornithologist from the Chicago area. That led him to the Chicago Academy of Sciences, home to the Gault collection, which includes bird specimens, dried plants and, as he had hoped, old film.

Mr. Gault’s films are not the only reels in the academy’s archives, but they are among the oldest. Dawn Roberts, the academy’s senior director of collections, was trying to raise money to digitize the reels when she received an email from Mr. Ó Mainnín.

The academy did not have the resources to digitize the Gault reels, but Ms. Roberts shared catalog notes with Mr. Ó Mainnín along with scanned journal entries and photographs belonging to Mr. Gault. Mr. Ó Mainnín brought those materials to the Irish Film Institute to see if it could help fund the digitization process.

Mr. McManus had secured some funding from a nonprofit when Rob Byrne, the president of the San Francisco Silent Film Festival, caught wind of the story. Mr. Byrne, who lives in Ireland, had been looking for an Irish project, and Mr. Gault’s reels presented a rare opportunity. The Silent Film Festival had a lot of experience with restoring silent films.

“Because the footage was shot by an American in Ireland, it’s fitting that, after nearly 100 years, the U.S.-Ireland connection endures,” Mr. McManus said.

Mr. Gault shot on 35-millimeter nitrate film, which was rare for a hobbyist because it was a very professional and higher-resolution medium, Mr. McManus said. The downside is that nitrate is also unstable and flammable, which makes the film hard to preserve.

“First of all, these are amateur films shot 100 years ago that, fortunately, nobody ever threw out,” Mr. Byrne said. “Films like these are disappearing. They’re a huge, single unique copy on a combustible, flammable, deteriorating film base. Fifty years from now, this film would not exist at all.”

Mr. Gault’s reels were in exceptional condition. After the funding was arranged to have a third-party laboratory digitize the reels, it was up to the Silent Film Festival to restore the footage. That job fell to a senior film restorer, Kathy O’Regan, who also happened to be a native of Gort, County Galway, a rural area in the west of Ireland not unlike the places Mr. Gault shot in Counties Cork and Kerry.

“It was magical to see it,” Ms. O’Regan said. “On a personal level, the first time I watched it was so exciting. There’s this one shot of two farmers who are planting potatoes, and I swear to God, one of the men is the absolute spitting image of one of my next-door neighbors. I know it’s impossible, but it’s wild just to watch.”

The 19 reels of film will amount to about 35 minutes of footage once the frame rate is adjusted. After they are graded and restored, Mr. McManus wants to screen the footage in Dingle. He hopes that if more local people see what Mr. Gault shot, they’ll be able to identify some of the people featured.

For Mr. Ó Mainnín, the film footage offered a chance to see familiar faces in a different light.

“I know all those people that were in the film, but they were older,” he said. “But that’s when they were young and strong and full of life, you know?”

As with the birds he studied, Mr. Gault observed the people of rural Ireland in their natural habitats. His reels show people dancing in the streets, baling hay, walking arm in arm.

And, yes, a dog smoking a pipe.