Michael Scott asks on the Genealogy Help board at Ancestry.com, "Is this just an eccentric flourish or does it mean something?"
The answer: Henry was suffering from an ailment common in the 18th and 19th centuries, known as "endorsial graphorrhea." At its most advanced stage the illness rendered a person incapable of writing his name without adding a tangle of needless loops and swirls, turning even a simple land transaction into a lengthy ordeal. The sufferer would stop writing only if his pen ran dry—or if one of his companions whacked him on the head with a heavy stick.
Thanks to modern medical therapies, the disease is now virtually extinct, with only occasional outbreaks in Equatorial Guinea.