the merrimac then went back to norfolk, where she boarded, night having come on apace. in the morning she aimed to clear out the balance of the union fleet. that night, however, the monitor, a flat little craft with a revolving tower, invented by captain ericsson, arrived, and in the morning when the merrimac started in on her day's work of devastation, beginning with the minnesota, the insignificant-looking monitor slid up to the iron monster and gave her two one-hundred-and-sixty-six-and-three-quarter-pound solid shot.