NEWPORT NEWS, Va. Was there a black cat aboard the Civil War ironclad USS Monitor, placed inside a cannon by a superstitious but desperate sailor as the vessel was sinking? Conservators had hoped to verify the legend as they worked this month to extract concrete-like sediment from two cast iron, smooth-bore cannons salvaged from the ship's turret. A crewman who had survived the sinking off the North Carolina coast more than 140 years ago maintained that he stuffed the feline into one of the 11-inch-wide, 17,000-pound barrels. And did he stuff his new wool coat and boots into the carriage...