Pope Pius IX and Washington Monument

I'm beginning preproduction on a documentary about the black marble stone sent by Pope Pius IX to be placed in the Washington Monument.  The stone was stolen by the Know-Nothing party and was then either broken up and thrown into the river or simply thrown in all togethor.  Our team has pinpointed the possible location of the stone in the Potomac River and we hope to excavate it during the course of the film.  Any knowledge on the stone or the Know-Nothings or the monument itself would be greatly appreciated.

Edited by awesome4productions