In the early 1940s, when there was no Lighthouse Beach in Edgartown and no electricity west of Chilmark, a man with a movie camera spent two August vacations exploring Martha’s Vineyard.

His color films were donated last year to the Martha’s Vineyard Museum, which this week presented their first public screening online. Research librarian Bow Van Riper narrates the 17-minute compilation, titled On the Vineyard: Summer Vacation in 1940 and 1941, which began streaming on the museum’s YouTube channel Tuesday.

Eager to chronicle his entire trip, Charles M. James started filming while the steamship Naushon was still loading in Woods Hole.

“The Naushon was the queen of the fleet: the biggest, most luxurious vessel serving the Vineyard and Nantucket,” Mr. Van Riper notes in his narration.

Mr. James’s footage is filled with sights that remain familiar today — Ocean Park in Oak Bluffs and the white-fronted houses of Edgartown among them — as well as some that were already passing into history as the 1940s got under way, such as a whaleboat davit repurposed as a garden ornament.

In some scenes, the effect on a 21st-century viewer can be faintly surreal, as in a dream of something familiar that comes with a peculiar twist or two. The Coast Guard station is on top of the Gay Head Cliffs. Traffic is going the wrong way in front of the ferry terminal in Oak Bluffs. All the cars are dark, bulbous and very antique-looking. And while young people appear in jeans, T-shirts and rompers, almost all the adults are wearing suits and dresses.

At the start of the 1940s, Mr. Van Riper explains, men like Mr. James donned suit and tie for a ferry trip — or even a day at the beach, where men and women alike wore street clothes unless they were going directly into the water.

The place to swim in Edgartown was the Chappaquiddick bathing beach, now the private Chappaquiddick Beach Club. Beach-goers rode a launch called Charlesbank from Memorial Wharf to get there. It would be years before the sands of Lighthouse Beach built up around the new Edgartown Light, floated down from Ipswich and installed in 1939.

Mr. James and his family also visited Katama, where nobody went swimming in those days, and roamed in their car as far as the Gay Head cliffs.

Throughout the newly digitized compilation, Mr. Van Riper’s narration deepens the viewing experience, adding detail and context to what might otherwise be fleeting moments of film.

It is with his help that we spot a Wampanoag farmer — the only person of color seen in the footage — who leads his ox cart down an unpaved side track, while an open-sided motor jitney loaded with tourists dashes past on the main road to the Cliffs.

Along with the Vineyard’s immediate contrasts, Mr. Van Riper also calls attention to longer-lasting shifts that were under way, from farm country to summer resort and from commercial fishing to pleasure boating. While there are still windmills on Chappy, that catboat being launched from the marine railway on Edgartown Harbor is for yachting, not fishing, he tells us.

There’s a greater — and darker — change in the offing, which Mr. Van Riper refers to while describing the stately, side-loading Naushon, built in the 1920s and one of the first steamers designed to carry motor vehicles.

“Three years after this film was shot, she’d be . . . serving the U.S. Navy as a hospital ship, and eventually receiving wounded soldiers off the beach at Normandy,” Mr. Van Riper remarks, in a brief intimation of the coming World War II.

But no such shadow dimmed Mr. James’s viewfinder, as he traveled to and around the Vineyard in what only later would be known as prewar years. Now part of the museum’s collection, his 80-year-old adventures combined with Mr. Van Riper’s narration are well-suited for digital replay, which allows limitless stops and starts for viewers who want to get a closer look at the details in the frame.

On the Vineyard: Summer Vacation in 1940 and 1941 with the James Family is available for online viewing at: youtube.com/user/MVMuseum.