"It is a precision instrument," the black man says, "performing calculations mechanically, employing neither electricity nor electronic components. The sensation of its operation is best likened to that of winding a fine thirty-five-millimeter camera. It is the smallest mechanical calculating machine ever constructed." Voice deep and mellifluous. "It is the invention of Curt Herzstark, an Austrian, who developed it while a prisoner in Buchenwald. The camp authorities actually encouraged his work, you see. 'Intelligence slave,' his title there. They wished his calculator to be given to the Führer, at the end of the war. But Buchenwald was liberated in 1945 by the Americans. Herzstark had survived." He gently takes the thing from her. Enormous hands. "He had his drawings." Large fingers moving surely, gently, clicking the black tabs into a different configuration. He grasps the knurled cylinder in his left, gives the handle at the top a twirl. Smoothly ratcheting a sum from its interior. He raises it to see the resulting figure in a tiny window. "Eight hundred pounds. Excellent condition." Dropping an eyelid partially, to wait for her response.