Jumbo was a huge steel vessel designed to contain the explosion of the first nuclear device at the Trinity Site some 35 miles southeast of here on July 16, 1945. It was 25 feet long, 12 feet in diameter, weighed 214 tons, and had steel walls 14 inches thick. Although it was not used in the test, it stood 800 feet from ground zero at the time and escaped without damage except for a steel superstructure around it that was crumpled by the blast. Jumbo was later used in experiments that blew out its ends, and this fragment comes from that vessel associated with the world’s first nuclear explosion.