When she was 17 Ellen Belet applied for a job at the Blair Academy, a private boarding school in Blairstown, N.J., near her family farm. It was 1908 and Henry Ford had recently introduced his Model T. This month Miss Ellen begins her 70th year as a campus institution as famous as the Old Academy Building. At the annual headmaster's dinner a few days ago she was given a standing ovation. "She has contributed so much and continues to contribute so much that we keep her around," explains James R. Kelley, Blair headmaster. (Mandatory retirement age for faculty is 65.)

Hired originally as bookkeeper at the school laundry for 10 cents an hour, she worked 10 hours a day. "The girls used to send me ruffled petticoats and all that stuff. After I got the bookwork done I'd iron them," Miss Ellen recalls. As the styles changed, petticoats disappeared. "Today the kids don't wear anything," she observes cheerfully.

The laundry was closed in 1954 because its suds were contaminating the Paulins Kill River, where farmers water their livestock. Miss Ellen was promoted to the job of managing the school bookstore. She works there from 8 a.m. to 3 p.m., keeping inventory ledgers in her old-fashioned script. But it is her unofficial job as housemother to the entire campus that has endeared her to successive generations of students.

"Every year she adopts a few of the boys and brings them presents," says Mark Lieberman, one of "Miss Ellen's boys" from the class of '74. "She really cares." Other Blair graduates of the Miss Ellen era include Stewart Cort, retired chairman of Bethlehem Steel, class of 1930, Bob Guccione of Penthouse, 1948, and John Sebastian of the rock group Lovin' Spoonful, 1962.

Miss Ellen never married. "The ones that liked me I didn't like, and the one I could get I didn't want." But this is not a complaint. She supports herself on an $80-a-week salary, Social Security and modest savings. "I'm very independent," she says. "If you don't depend too much on other people then you don't get hurt."

The second child of Swiss immigrants, Ellen was named after her godmother, the daughter of President Chester A. Arthur. Ellen's mother, before she married, was a maid in the White House, and Miss Ellen treasures a letter of recommendation President Arthur gave her mother. Although Miss Ellen has three nieces and four nephews, some of them in New Jersey, she prefers living alone in a tiny room above the Martha Washington Tea Room. "I'm a spinster," she explains, "and it's nice to live where there's a little action." But she misses Blairstown's livelier days when there was still a movie house.

A birdlike, meticulous lady, Miss Ellen eats all her meals at the tea room. Every evening she goes next door for a pinochle game with a neighbor. Miss Ellen is not at a loss when asked, inevitably, to what she credits her 87 years. "I don't smoke," she replies, "and I enjoy a daiquiri before dinner."