CAMBRIDGE — Tradition says that the shimmering blue bottles on Brattle Street hold spirits.
The bottle trees, part of an art exhibit on the lawn of History Cambridge’s office that was inaugurated this weekend, are meant to commemorate the people who were enslaved in Cambridge in the 17th and 18th centuries.
The iron trees’ limbs are capped with 300 indigo glass bottles that are illuminated by solar-powered lights at dusk.
Bottle trees are a tradition that originated in the Congo River region of Africa centuries ago and were meant to trap spirits, good and evil, in their colorful bottles, according to Pam Goncalves, the head artist at Black Coral, the Boston-based artist collective that created the trees.
Slaves brought the tradition with them to America, and the bottles on the lawn at the 159 Brattle St. represent people like Cesar, Caesar, Prince, and a woman whose name is unknown who once toiled in the grand house behind the installation.
“The ugly can turn into beauty,” Goncalves said.
The bottles are arranged in two concentric circles with larger trees in the outer circle representing the enslaved adults, and the inner circle and a small tree in the center, representing the children.
Many people think of American slavery as a Southern institution, and there’s little education about Northern slavery, said Marieke Van Damme, the executive director of History Cambridge.
“That’s what we are hoping to do with this exhibit: highlight this history that we’ve chosen to not talk about and that many people don’t know about,” she said.
History Cambridge has been focusing on anti-racism since the murder of George Floyd and ensuring they are telling the story of everyone in Cambridge, Van Damme said. The installation, funded by a Cambridge Arts grant, is part of those efforts.
At the inauguration of the exhibit on Saturday evening, African drummers played, a poet recited the names of some of those who were enslaved in Massachusetts, and the crowd took part in the pouring of libations, another ceremony to remember ancestors.
Goncalves hopes that the installation prompts people to reflect and do a little research. She grew up in the Boston area and heard little about Northern slavery in school, and, for her, working on the bottle trees was personal.
“I touched my blood ancestors,” she said. “To let them know they’re not forgotten.”
The installation, titled “Forgotten Souls of Tory Row: Remembering the Enslaved People of Brattle Street,” includes signs in front of the bottle trees about slavery in Cambridge and on plantations in the West Indies, some of which were owned by Brattle Street residents.
“You could put up a sign out front until the cows come home,” Van Damme said. But when you “see something that is usually not there, it makes you stop and want to know why and you investigate and then you learn something.”
On Sunday afternoon, the display caught the eye of walkers, cyclists, and skateboarders passing by, some of whom commented on the work’s beauty.
Rita Smith, 72, and her husband were among those strolling past the bottle trees on Sunday afternoon. The Cambridge couple walks down Brattle Street frequently and saw the piece being assembled, prompting them to stop and read the history on the signs.
“It’s bringing attention to an issue we have to be reminded of,” Smith said.
Smith recalled one evening a few weeks ago when she walked by as the sun was setting behind the bottles.
“Every one of them was aglow,” she said. “It only lasted a couple of minutes before it was gone, but it was gorgeous.”