Clockworking

From the ground, the Custom House Tower clock is a stone-faced marker of time, serene and impartial, its four faces looming over the Financial District's stream of commuters and blinking traffic.

From behind its faces, 325 feet up, it is more mortal than eternal, a creature that spends each winter locked in furious battle with the wind and the weather, struggling desperately to go on ticking.

This is the view most familiar to David Hochstrasser, who comes to the rescue when the clock stops or loses time. A little snow or ice on the end of one of the 11 1/2-foot minute hands can place such a heavy burden on the internal works that it stops altogether, usually as the hand is climbing toward the 8 or the 9.

''It seems no matter which way the wind is blowing or what time it is, it's always on one of the faces, trying to stop the clock," he said. ''It's almost like a living organism. Sometimes you hear it straining and creaking and groaning, and of course, hearing it tick is kind of like a heartbeat."

But it is a small miracle that it works at all. The clock, which was completed along with the tower in 1919, did not work properly through much of the last century, Hochstrasser said. Its half-century-old movement -- the gears and pendulum and electric motor that winds it -- was built to drive a much smaller clock. As he puts it, it is almost like a Toyota Tercel engine trying to power an 18-wheeler.

The clock only runs as well as it does now because, in a rush of youthful exuberance, Hochstrasser and his brother, Ross, came up with a plan to fix it. In 1985, Boston Edison, which wanted to fix the clock for the city in honor of the company's centennial, liked their idea, and it took more than two years of haggling with city officials (the city owned the tower then) and historic preservation groups for the brothers to begin the project. With great fanfare, at a celebration on Oct. 29, 1987, they started it running again, and it's been going -- albeit temperamentally, and with a few hiatuses for renovations -- ever since.

David Hochstrasser, now 42, handles most of the maintenance these days. The clock is almost like his child. He knows its every quirk and weakness, and he sympathizes with its plight.

''Knowing what we're asking it to do and what it was designed to do, I guess I feel sorry for it," he said. ''I know it's a strain."

Wiry and slight-framed, with a shock of black hair and small glasses, Hochstrasser looks more like an earth science teacher than he does Father Time. He has been fascinated with clocks for as long as he can remember; he took apart his grandfather's wristwatch when he was 4 or 5 years old (he was punished so severely, he didn't touch another clock for a decade). He recalls as a child driving into the city from Weymouth with his family and noticing the Custom House Tower clock -- and how it was always wrong. After tinkering with pocket watches in high school, he and his brother learned more complicated repair techniques from an expert in Scituate; they opened a subsidiary of that mentor's Clock Shop in 1982.

Hochstrasser spends most days in his shop in Hanover, The Clock Shop. Modest as its name, the place is a fluorescent-lit storefront in an old strip mall near the intersection of routes 123 and 53.

On a recent afternoon there, as a wet snow fell from a darkening sky, Hochstrasser fretted over a customer who failed to pick up a clock he'd spent hours fixing. These days, clocks are more ornamental than essential, he says, and people occasionally abandon their clocks at his shop.

''That's my life," he said.

But Hochstrasser was animated as he showed a visitor around. Ticking and clicking from every corner, the scores of clocks together sounded almost like dripping water. There were cat-shaped clocks with their pendulum tails switching; a tribe of grandfather clocks standing at attention; clocks painted with roses and curlicues and Colonial villages. Clock guts covered a large worktable. At 4 o'clock, there arose a cacophony of chimes and cuckoos and spinning Bavarians and music box melodies.

The Custom House Tower, though, is never far from Hochstrasser's mind, and bits of it lay everywhere: a photograph of a peregrine falcon, wings and tail feathers spread, flying straight at the camera, taken by Hochstrasser from a door in the clock's south-side dial.

Hanging on a wall was one of the four wooden minute hands that he and his brother replaced in 1987 with a lighter composite plastic, a bit of ingenuity that eased the burden on the old movement by about 48 pounds -- one of the main reasons, Hochstrasser says, the clock has been running more reliably.

And on a table lay the tower clock's old brass escapement wheel, the gear at a clock's heart that provides the ticking sound, which Hochstrasser replaced years ago, carving its 36 teeth out of a solid bronze wheel. It was the first escapement wheel he'd ever made.

Every so often, usually in the wintertime, Hochstrasser gets a call from the Marriott, which turned the Custom House Tower into timeshare condos in the late 1990s, to report that the clock has stopped again. So Hochstrasser gets into his Toyota Matrix and makes the trip into Boston. He takes two elevators to get to the 24th floor.

Most people, he acknowledges, are unimpressed when they see the movement, which is about 6 feet tall and mounted on a 6-foot high wooden platform surrounded by glass. Before Marriott bought the building, the movement was in the center of an otherwise empty room. The room is now a game room, and the movement is now against the clock's north face, surrounded by a foosball table, an air hockey table, a pool table, and a TV mounted on a wall.

Small things get the clock working. Recently, Hochstrasser put a tiny counterweight on a shaft that runs from the movements to the dials because moisture had settled into the hands on the east and west faces, throwing them out of balance. Often the ice and snow that knocked it out of whack have melted by the time Hochstrasser arrives and he merely has to get it running again.

He always sets it to his wristwatch, which picks up an ultra low frequency radio signal from the US National Bureau of Standards, whose atomic clock is the ultimate arbiter of time in America. The Custom House Tower clock is not nearly so accurate, the wind can toss the hands in a 1 1/2-minute arc.

''The clock doesn't turn the hands so much as limit how far the wind can push them," he said.

Hochstrasser sells wristwatches like his for just over $100. In an age where almost everyone has a cellphone that tells the time almost as accurately, Hochstrasser acknowledges that the grand old clock tower has become superfluous. Yet people don't like it when they see that the clock has stopped, he says.

''I know people at least look up and notice," he said. ''What motivates me is knowing people still care."