It’s possible to put two and two together and come out with a number not exactly four. Ann Coleman Allen of West Tisbury bears the last name of one of our original settler families, and she teaches courses on Vineyard history. One could reckon, therefore, that her interest in the subject stems from the irresistible pull of family genealogy.

“Not so,” she says with a charming, self-deprecatory laugh. While her first husband hailed from a family of Allens, they weren’t those Allens. On the other hand, Ms. Allen’s maiden name, Coleman, does devolve from an early line of Nantucket Colemans, but that, of course, carries less currency on our shores.

All the same, Ms. Allen is a Vineyard washashore who only barely missed being a native. She was born in New York city in 1933 and the very next year was conveyed here for her first summer in Chilmark. That year her parents had purchased the decommissioned Cape Higgen schoolhouse on the North Road in Chilmark, the landmark that now is a white Cape with black shutters and a small rooftop bell, surrounded by an emerald lawn. Every summer young Ann spent in that bucolic locale — sometimes extended into over-winter stays with a nearby farm family — reinforced her sense of the Vineyard as home.

After a series of boarding schools and studies at Vassar College, Ann went to work as a researcher (a fact-checker) at Newsweek Magazine. It was under the Newsweek aegis that she met and married writer Douglass Allen, a native of Cincinnati, Ohio. The couple moved to New Canaan, Conn., from where Mr. Allen commuted to New York and Ann to New Haven, where she worked in President Lyndon Johnson’s anti-poverty program. In 1967, Mr. Allen died of a heart attack five months before the birth of their daughter, Katy.

The widowed mother and baby girl moved to Bannockburn in Bethesda, Md., a community, interestingly, that had been started by her aunt, Mary Fox Herling, as an asylum for refugees in flight from the Nazis.

Ann treated her daughter, as she had been, to idyllic summers on the Vineyard. Katy pleaded with her mother to let them live on the Island year-round. Ann agreed, although the youngster followed in her mother’s footsteps of attending schools on the mainland.

In 1980 Ms. Allen got together with William Elbow, a Vineyard summer kid whom she had not seen since she and her brother had played summertime kick-the-can with the Elbow children in the 1940s. Mr. Elbow is well known to Islanders as a longtime administrative assistant in various departments in the town governments of West Tisbury and Chilmark, respectively, and a member of the Edgatown Board of Health. The two of them proceeded to restore the schoolhouse and then to begin a 23-year project on a property they purchased on Mullen Way in Edgartown.

Ms. Allen served as librarian at the Historical Society from 1988 to 1993, before establishing the CHiP program — the initials standing for Community History Project — at the high school in 1994, the same year that the couple was married. Mr. Elbow is now retired, the couple currently residing in West Tisbury. Katy, 41, attends graduate school and teaches in a small kindergarten through grade 12 school in northern California.

Ms. Allen’s urge to communicate an abiding “obsession” with history was heightened when she and award-winning Martha’s Vineyard Regional High School teacher Dr. Margaret Harris inaugurated their CHiP program at the school.

Ms. Allen explains: “The students were encouraged to take on any topic and present their findings in virtually any media that appealed to them. There were no lectures, although they all had to do some writing.

“We took them on trips to places like Cuttyhunk, Mystic and the Hartford School for the Deaf, the last since it is so relevant to the Island’s large population of deaf people in the 19th century.”

Each course would culminate in an exhibit of the student’s work at the high school and a publication of their projects in the annual CHiP Supplement.

In 1997 Ann designed an Island history course for adults — The Short Course in Island History — to help support the high school program. Until her retirement from the high school project a few years back, Ann charged a modest fee for the course. Now and for the past several years she has offered it free in summer, usually in July or August. Since it was inaugurated, Ann estimates that more than 300 Islanders and longtime summer visitors have taken the course.

Ms. Allen’s current Island History Course Spring ’09 is taking place over nine weekly lectures at the Vineyard Haven Public Library, each talk running from 6:15 p.m. to 8:35 p.m., with a short break for coffee and cookies (home-baked by the historian herself). The class for Tuesday, April 21 was billed as Camp Ground to Cottage City: We Become A Summer Resort. The second-to-last class in the series is scheduled for Tuesday, April 28, and the subject will be Our Multicultural Island: Natives, Immigrants and Visitors. The final class will he held on Saturday, May 2, from 1 to 4 p.m. and will include an open discussion and guest speakers Kent Healy and June Manning.

When this reporter caught up with Ms. Allen for her April 13 lecture entitled Whaling: The Vineyard Goes Global, she found a slim woman with vivid blue eyes and a lustrous bob of silver hair addressing a standing room only crowd in the library’s lecture hall. Dressed in a white-collared shirt, a denim jacket, black trousers and navy blue tennis shoes, Ms. Allen was the very image of the very Vineyard historian.

Our lecturer took us through the early days of along-shore whaling, how placing try-pots (cauldrons for rendering whale oil) on the decks of whaling ships in 1750 turned the vessels into factory ships and eventually allowed them to extend their voyages into the Pacific for three and four year tours. She explained that Nantucket was the whaling capital in the 18th century but that a sandbar across the mouth of Nantucket harbor, over which the increasingly large factory ships could not pass, caused a steep decline in Nantucket’s output by the mid-19th century.

Reporting that the Vineyard is thought to have supplied more personnel to the whale fishery than any other area in New England, she gave her students a dramatic insight into the relatively minor role we played as whaleship owners: whereas in the near-century 1784 to 1876 a total of 61 ships were registered in Edgartown and Holmes Hole combined, 364 were registered in Nantucket and 736 in New Bedford in that same period. Shortly before the Civil War, the discovery of in-ground petroleum in Pennsylvania signaled the eventual decline of the whale oil market. Meanwhile the new incursion into the Arctic, led by Vineyarders such as the renowned Hartson Bodfish, on the hunt for bone (baleen) in bowhead whales, kept the business alive for another few decades — at least until 1907 when an abrupt change in women’s fashions, from hoop skirts and corsetted “wasp” waists to the “slim look” put the last of the whalers out of business.

Armed with meticulous notations and dates on both sides of a standing blackboard, Ann Allen’s attention to detail, warm smiles, wry humor, and talent for bringing alive the images of men and women and, as at that night’s lecture, whales long dead, made for a sprightly two-and-a-quarter hour talk.