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When it’s time for the clock at the center of Philadelphia to skip forward or back an hour, Joe Brasky has been the one to make it happen.

Come 2 a.m. on the appropriate Sunday, Brasky, the building services manager at City Hall, climbs up inside the masonry tower and manually cranks the 15-foot, 235-pound minute hands to adjust for Daylight Saving Time.

Known as the city’s “clock guy,” Braksy was taught by Lancaster clockmaker Bob Desrochers to properly wind each of the timepieces at the intersection of Broad and Market, turning them forward or backward when the seasons change.

It’s not that all that difficult a process, Building Services Administrator Richard Mariano told Billy Penn in 2018. But it is tedious.

There are four clock faces in the tower, one each looking north, east, south and west. After Brasky cuts the power — or “stops the escapement,” for those fluent in clockspeak — he must adjust each minute hand individually.

Accuracy is critical. “The challenge is lining all four clocks up,” Mariano said

After manually moving the giant metal pointers, Brasky will take a quick walk around the outside of the building, checking that the time on each clock is exactly right. If one clock is wrong, if it’s even 30 seconds off, he’s back up in the tower for round two.

Air-powered clock hands were tough to control

The time-changing task isn’t as daunting as it used to be. City Hall’s current chronometers were installed in 1947, according to Lancaster clockmaker Desroshers.

These days, the mechanics controlling the clock hands run using electricity, so it’s not difficult to stop their motion by cutting the power if you want to adjust the time.

But before 1947, Deroshers said, the City Hall clocks operated on a pneumatic system, meaning they were powered by air — which is much harder to control, and even tougher to set forward and back with accuracy.

Making sure the display was accurate system used to be essential, he noted.

“Large clocks like this were originally intended to be kind of a regulator,” Deroshers explained. “You knew what time it was, so you could adjust your time piece to keep up with it.” Now people use their phones, he admitted, instead of needing an external point of reference to stay in sync.

Even so, it’s still useful to have a common physical reference point, Deroshers said. “It’s important to maintain that timekeeping.”