sixty degrees, multiplied by four minutes, gives precisely twenty-four hours — that is, the day unconsciously gained. In other words, while Phileas Fogg, going eastward, saw the sun pass the meridian eighty times, his friends in London only saw it pass the meridian seventy-nine times. Fogg had thought it was one day later than it actually was, because he had forgotten this simple fact. During his journey, he had added a full day to his clock, at the rhythm of an hour per fifteen degrees, or four minutes per degree, as Verne writes. At the time, the concept of a de jure International Date Line did not exist. If it did, he would have been made aware that it would be a day less than it used to be once he reached this line. Thus, the day he would add to his clock throughout his journey would be thoroughly removed upon crossing this imaginary line. But a de facto date line did exist since the U.K., India, and the U.S. had the same calendar with different local times, and he should have noticed when he arrived in the U.S. that the local date was not the same as in his diary (his servant Jean Passepartout kept his watch set to London time, despite the clues from his surroundings). Line-crossing ceremonies relating to the IDL Ceremonies aboard ships to mark a sailor's or passenger's first crossing of the Equator, as well as crossing the International Date Line, have been long-held traditions in navies and in other maritime services around the world. Notes References Bering Sea Chukchi Sea Kiribati Samoa Pacific Ocean Time