In November 1908, suffering from the effects of several unknown illnesses (now believed to be pellagra), Jack and Charmian went to Sydney, Australia for medical treatment and cancelled the rest of their world cruise on the Snark. Jack was operated on for a double fistula and sensitive to ultraviolet rays of the sun. This hat was to shade his face and ears. He had suffered terribly from exposure to ultraviolet rays during their Snark cruise, but rapidly regained his health back in the California climate.