Though Chang and Eng were the original "Siamese twins" exhibited by P. T. Barnum, they were not Siamese but Chinese. And though a popular impression persists that they died within a few hours of each other as an inevitable result of their physical union, this is not true, either. The facts were recorded in century-old medical records, but were generally ignored until Georgetown University's Dr. Worth B. Daniels browsed around a bookstore, came across a long-neglected autopsy report: Eng died of fright.
Born in 1811, the twins were joined at the lower end of the breastbone, mainly by cartilage and ligaments which...