Backstory: She keeps the lighthouse fantastic

On the outer rim of Boston Harbor atop a rocky three-acre island sits a tall, whitewashed beacon – the Boston Light. For 224 years it has flashed a warning to everyone from captains of tall ships to modern sailors of war, commerce, and leisure.

As a frosty winter wind whips whitecaps around the island, Sally Snowman, bundled in heavy jacket, hat, gloves, and boots, climbs the metal spiral of 76 steps in the lighthouse, maintaining the daily ritual of generations of Boston Light keepers before her.

She is the last Coast Guard lighthouse keeper in the US – at the oldest lighthouse site in the nation. And she's on her way to inspect the lens, polish the heavy glass prisms, and grease the wheels that rotate the five-ton mechanism – the very same equipment installed in 1859.

"I've had many jobs over the years, but this is absolutely the best one," says Ms. Snowman who, from here inside the lighthouse's 360-degrees of windows, can see the Weymouth shore where she grew up dreaming of working in the historic Boston Light.

As a walking encyclopedia of Boston Light trivia and the author of the book "Boston Light: A Historical Perspective," Snowman considers her job an honor. "I know the position is special, I'm not special."

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Boston Light was the first light station in North America; built in 1716, it was destroyed by the British during the American Revolution, and rebuilt in 1783. Once regarded as the salvation of boats struggling to enter the rocky and narrow Boston Harbor passage, it remains a familiar landmark on nautical charts and – despite improved navigation technology – continues to help keep modern ships from running aground.

It is the only remaining US Coast Guard facility with an official keeper because – when it was decided to automate all the country's lighthouses by 1990 – preservation groups appealed to Congress and the Coast Guard to maintain a human presence on the island. It was made a part of the national park system in 1996 and is maintained by a partnership of federal, state, and local officials, including the US Coast Guard and Friends of the Boston Harbor Islands.

With a tub of oil and a spark of fire to the wick, the current lantern was first lit in December 1859, shining about 16 miles to sea. Electrified in 1948, the 1,000-watt glass light bulb – the equivalent of 2 million candles – is now visible for 30 miles.

The lantern is a nine-foot tall mechanism. Its lens consists of 336 12-sided glass prisms mounted in a brass frame set on motorized wheels that rotate 360 degrees. This lens surrounds a modern bulb, which refracts and reflects the light to magnify 1,000 watts into a single beam of light.

The irreplaceable prisms are chipped and cracked from a century of keepers pouring tubs of whale oil to fuel the old flame at the center of the lens. It underwent the largest restoration in its history last fall, says Snowman's assistant light keeper, Ed Petrie. Restorers filed down rough edges on each prism, then recaulked and repositioned them around the bulb. The lantern and its gears were also realigned and the wheels replaced to ensure smooth rotation. Snowman says that if the wheels are oiled just right, she can turn the whole contraption with her finger, with less than 15 pounds of pressure.

Snowman need not keep the fire lit or the wick trimmed like her predecessors, though she has to polish and clean the 4,000 pounds of glass and gear at the top of the 102-foot tower. With a special formula of distilled water, isopropyl alcohol, and Woolite, Snowman gently cleans the prisms surrounding the lamp with a lint-free cloth. Because the mechanism is so fragile, she cleans it only when absolutely necessary, maintaining it with a feather duster weekly.

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"This job found me, and it's a dream come true," says Snowman, the keeper since 2003.

Dreaming of being a lighthouse keeper might well be a tougher trick to achieve than, say, the longshot dream of making it big as a movie star. In Snowman's lifetime there was no established career path to follow, and – with automation – job prospects were dwindling. Further, her 69 predecessors were men.

That Snowman ever landed the last existing Coast Guard lighthouse keeper post is because, as Coast Guard Commander Tom Miller puts it, "This really is Sally's whole world."

Indeed, while Snowman has a PhD in education and has taught in preschool on up to university level, Boston Light was a lifelong beacon to her. She spent 30 years in the Coast Guard Auxiliary and began volunteering at the lighthouse in 1994, the same year she got married there to Jay Thompson, a fellow auxiliary member.

"I was a volunteer when I applied for the job and I got it, but I had no experience as a lighthouse keeper," she says, explaining that after the Sept. 11 attacks, the Coast Guard wanted to better utilize its staff and so searched for a civilian light keeper to take over for the full-time job. "But they were looking for an educator, and I love that part of the job, too."

Snowman works up to 80 hours a weekeven in the slow season. She doesn't live permanently on the island, nor is she alone when there. She shares island duties with Mr. Petrie, and together they tackle leaks in the roof of the 19th-century shingled island house, failed electrical wiring, and even the heavy lifting (such as hanging a 60-pound Christmas wreath). She is also assisted by Coast Guardsmen for more gnarly tasks, like rebuilding the dock when it gets washed away in a heavy storm. She spends most of her time during the summer conducting public tours, and handling general island maintenance.

In the winter, she returns to the mainland every 10 days to restock supplies and do research.

On any given day on the island, Snowman has cooked breakfast and is out the door by 8 to log meteorological data and visitors. (Such logs date back to the 1800s.)

Other daily duties include tending the cistern where rainwater is collected. A wooden dip stick goes to a depth of 58 inches, beyond which the cistern overflows and she can luxuriate in long showers, which are normally limited to about three minutes because of water conservation.

But this tough lady has a soft side, too, and she regularly takes time on sunny days to sit on a bench and write or draw, contemplating life on an isolated island on the metropolitan fringe.

Though she's halfway through a four-year leave of absence from her job at Curry College in Milton, Mass., she's in no rush to return. "I far prefer to be on the island, to be out here in nature," she says, as she walks a paved path, scanning the water through a squint against the bright winter sun. "And I just love lighthouses. Historic light keepers had so much passion for their work, and I try to respect that tradition."

She pays homage to that tradition when she dons her summer garb. Resembling a character from "Little House on the Prairie," she wears a hand-sewn colonial frock with an apron and bonnet, and waves a handkerchief when visitors arrive on the island by ferry. Snowman hands out stories of shipwrecks and chocolate chip cookies she bakes herself, then lets her visitors explore.

"It hasn't really hit me that I'm the last keeper of a Coast Guard light station," she says. "I'll be here until I tire of it or the Coast Guard tires of me, but that thought really hasn't crossed my mind."