COPAKE—When Copake Town Clerk Larry Proper went on vacation this summer he came back home with more than a suntan and souvenirs.

He returned with a new leaf on his family tree. Ida Sedgwick Proper was not only a painter and writer of some prominence, but was also a town clerk.

Mr. Proper and his wife, Teri, went on a week’s vacation to Maine July 13 through 20. It was the first time either of them had ever been there. They visited Wells, Kennebunkport, Bar Harbor and later met up with their son Todd and his friends at a place called Monhegan Island.

Accessible only by boat, the hilly, rocky island is just about one-square-mile in area and is situated about 11 miles off the Maine coast. The year-round population numbers about 65.

They took a one-hour ferry ride from New Harbor on the mainland to the island to join Todd and his friends, one of whom has rented a bungalow there in the summer for 30 years.

“It was like stepping back in time,” said Mr. Proper, it wasn’t only the old weathered look of the buildings, but the relaxed way of life.

No cars are on the island and no paved roads. Twelve miles of gravel and dirt trails thread through the woods and up to the cliffs overlooking the sea. These are the highways and the primary mode of transportation is one’s own two feet. Mr. Proper does recall seeing golf carts and a pickup truck or two.

Electricity comes from a generator system on the island along with solar panels. With much of the island preserved as “wildlands,” only a small portion is developed—the village around the harbor, where lobster traps are the decoration of choice.

Businesses and public buildings include art galleries, a museum, a couple of inns, a fish market, a luncheonette, a brewery, an ice cream/pizza parlor, a provisions store, gift shops, a library, a one-room school house, a real estate office to handle island rentals and, of course, a lighthouse.

While there are plenty of birds and ocean-life around, there are no native animals, though Mr. Proper noticed a few dogs.

Amid all the hiking, relaxing and fresh seafood eating, Mr. Proper’s son picked up a book for him as a gift, “Images of America Monhegan Island.” Published in 2009 by Arcadia Publishing, the softcover 127-page book consists largely of historic black and white photographs with captions detailing what the place pictured is and when the photo was taken.

On page 65, Mr. Proper came across a photo of a backyard. A modest house appears to the left with an awning jutting out above the back door. Comfortable old white wicker armchairs are situated in clusters around small wooden tables in the yard.

The caption reads: “Ida Proper’s tearoom, located outdoors on her back lawn, was a popular gathering spot in the 1920s and 1930s… Ida Sedgwick Proper was not only known for her tea but became one of Monhegan’s first historians. In her 1930 publication, ‘Monhegan, the Cradle of New England,’ she writes of the Native American history and early exploration and settlement of the island. She was also a well-known artist, doing much of her painting during her visits to Paris.”

When Mr. Proper arrived home and began to research Ida Sedgwick Proper, both online and in his 783-page “Proper Genealogy and History” book by Lewis G. Proper (2010), he discovered Ms. Proper was born in Iowa in 1873. She saved her money to “realize her ambition to study at the Art Students League in New York City” and later earned a scholarship to study in Munich and Paris. She exhibited her paintings in Paris, New York, Philadelphia, Minneapolis and other cities.

She returned to the U.S. shortly before World War I. A self-described “feminist,” she became active in the suffrage movement and “served as art editor of The Woman Voter, the journal of the suffrage world,” according to the genealogy book.

She was a teacher in a girls’ school in Pennsylvania, and worked for the government as a cataloguer in the ordinance department assigned to investigate why guns were being shipped to troops in France without matching ammunition.

She was subsequently instrumental in the capture of a German master spy who possessed “plans for the sabotage of the American continent,” the book said.

While working as news editor at Power Magazine, she vacationed on Monhegan Island and eventually built herself a small house and lived there.

On the island, Ms. Proper became noted for her flower garden. By one online account, she became town clerk and operated an art school there. She died in 1957 at the age of 84.

The first Propers arrived in New York from Germany in 1710 and settled on the original Livingston Manor, which encompasses the present day towns of Livingston, Germantown, Clermont, Taghkanic, Gallatin, Copake and Ancram.

Based on his research Mr. Proper, a history and genealogy buff, found that “eight generations back on my family’s side of the Propers and six generations back on Ida’s side, we had a common grandfather, Johann Pieter Proper/Propert.”

So Mr. Proper’s sixth great-grandfather and Ms. Proper’s fourth great-grandfather were the same person.

Serving as town clerk is something of a Proper family tradition, perhaps starting with Ida Sedgwick Proper. Mr. Proper has served as Copake town clerk for 18 years, so far, 1986 to 1998 and 2012 to the present and his father, Otis W. Proper, served the town as clerk from 1960 to 1968.

Mr. Proper said he had never heard tales of Ida Sedgwick Proper before and was shocked to find out about her on an island off the coast of Maine.

To contact Diane Valden email