Joe, from Lorton Stone, was explaining how the stones were placed in the missile-silo-like things.
He said the stonework at the Eisenhower Memorial consisted of two types of materials. Things like the flooring and the stonework on the missile silo-ish columns were done with whole pieces of rock. The silo pieces weighed about 400 pounds each. Horizontal pins were drilled into the inner concrete columns. Then metal dowels were used vertically to connect the pieces to each other. None of the 400 pound pieces touched each other but each could be pivoted out on the dowels for maintenance. He drew a sketch of how that worked.