LARGEST ON MISSISSIPPI—New Orleans's newest revolver crane derrick barge, the largest ever put into service on the Mississippi River, is shown lifting a test load of 340,000 pounds. The new derrick, Kent, owned by T. Smith & Son, Inc., boasts a 120-foot boom mounted on a traveling gantry 40 feet above the deck of its 250-foot-long barge. In addition to its heavy-lift capability of 310,000 pounds over a 43-foot radius, the big derrick has its own special clamshell bucket with a 32-cubic-yard capacity. The bucket, said to be the world's largest, can pick up 42,000 pounds of coal in a single bite. The derrick is named for Kent McWilliams, principal T. Smith & Son stockholder, who officiated at informal christening ceremonies recently.