Since this demonstration was new and different from anything ever done before, complete reliance was not placed on mechanically operated control rods. They were prepared to flood the pile with cadmium-salt solution in case of mechanical failure of the control rods. Each group rehearsed its part of the experiment. The man at the controls threw the switch to withdraw them. A small motor whined.
All eyes watch the lights which indicated the rod's position.
But quickly the balcony group turned to watch the counters, whose clicking stepped up after the rods were out. The counters clicked faster. The graph pen moved up. All the instruments were studied, and computations were made. The trace will go to this point and level off.