Unbelievably, these joists turned out to be the ca. 1812 lower joists from the framing of the Mansion's wing roofs.  They had been removed when the Mansion's wings were raised to two stories and reused by the duPonts in their additions to the Bowling Alley.  While the historic joists had been cut down from their original lengths and installed upside down, they were otherwise perfectly preserved.  Even more extraordinary, when the carpenters looked under the south wing, they found that it was supported by intact sections of the ca. 1812 upper joists.