One day more than two centuries ago, a Maryland slave of West African descent took a smooth stone he had probably found in a plowed field and slid it between the bricks of a furnace he was building.
The slave might have believed, as West Africa's Yoruba culture held, that such stones had connections to Eshu-Elegba, the deity of fortune, and were left behind like mystical calling cards after a lightning strike.
The bond servant sealed the stone into the brickwork, where it would stay for generations, an artifact of the enslaved man as much as the god whose favor he sought.
On Monday, the University of Maryland unveiled, among other things, details of the stone's discovery at the Wye House "orangery" - a jewel of European architecture, now found to have imprints of the slaves who built it.
The discoveries were made over the past few years by a team headed by anthropology professor Mark Leone on an Eastern Shore estate where abolitionist Frederick Douglass once was a slave.
The team also found West African-style charms buried at the entrance to what turned out to be the slave quarters at the orangery, which was a state-of-the-art greenhouse, and pollen from exotic plants the slaves used.
The findings reveal cultural stamps left on the plantation by some of the slaves who lived there, Leone said, and give voice to their often anonymous lives.
"This is a uniquely American event," he said. "It is part of the creation of African American culture. So you can see that it is a wonderful set of anthropological discoveries."
Leone said his team started work on the Wye plantation, outside Easton, six summers ago and has been working on the orangery for 21/2 years.
The estate is occupied by retired lawyer Richard Tilghman and his family, who are descended from Edward Lloyd, who first settled in the area in the 1650s. The Tilghmans paid for the orangery research.
"Our family . . . has lived on this property since it was acquired by my ancestor in 1659," said Tilghman, whose mother inherited the property in the 1990s.
"We encouraged professor Leone to do some archaeological work around the greenhouse for two reasons," he said. "One, to learn more about the slaves, and two, to learn more about what went on in the orangery."
He called the discovery "fascinating," adding, "I hope that it will advance the understanding of the . . . spiritual life of African American slaves. That, to me, seems to . . . be pretty important."
Leone said the orangery was built about 1785 behind the main house, whose plantation Douglass described in an autobiography as "one of the largest, most fertile and best appointed" in Maryland.
Today, the orangery - so called because oranges and lemons were grown there - is the only surviving 18th-century greenhouse in North America, the university said.
Leone said his team discovered that one of the two rooms off the greenhouse must have been the quarters of the slaves who manned the facility.
"We proved that one is a slave quarter because of what we dug up in it," he said. "Outside the . . . doorstep of the quarter we dug up two prehistoric projectile points and a coin buried directly in line with the middle of the threshold."
"This is the kind of signature material that shows religious practices with their origins in Africa," he said.
In July, the smooth six-inch-long stone - technically a pestle, or pounding stone - was found in the bricks that formed the roof of the furnace that heated the greenhouse, he said.
"We recognized it as a talisman," Leone said. "It would only have been put there by a slave, and it . . . was exactly parallel to practices used in West Africa."
There, he said, "stones in the form of axes which are found on the surface of the ground are interpreted as the concrete manifestations of thunderbolts or lightning strikes from a deity . . . called Eshu-Elegba."
In Maryland, the stones and arrowheads were made and left behind by prehistoric Native Americans who inhabited the Eastern Shore years before the Wye plantation, Leone said. The objects often would turn up in the plowed fields after a rain.
Leone said the stone was placed amid the bricks by the slave who built the furnace: "We infer . . . that the man . . . was using and believed in the North American version of the hybrid religion whose origins come from West Africa.
"You would pick up the stone, and you would put it someplace because it has the power of the deity," he said.
Leone said the stone adds an African dimension to a building erected with "the highest-style European architectural principles."
"So it now has two faces," he said.
The same went for the slave quarters, probably built by the same man, or men, Leone said.
Buried there between 1785 and 1820 were two projectile points - arrowheads - and a coin. The purpose, he said, was "a combination of protection and worship."
As for the coin, he said, its "magical value was much greater than its monetary value."