“Three Sundays in a Week”

In 1841 Edgar Allan Poe pointed out the confusion that can result when a ship reckons time while circling the world. Captain Smitherton and Captain Pratt have just returned from circumnavigating the globe, one traveling eastward and the other westward, while Kate and her father Mr. Rumgudgeon have remained in London. On reuniting, they discover some confusion: Captain Pratt thinks that tomorrow will be Sunday, Smitherton thinks that yesterday was Sunday, and Kate and Rumgudgeon think that today is Sunday. Finally Smitherton says:

What fools we two are ! — Mr. Rumgudgeon, the matter stands thus: The earth, you know, is, in round numbers, twenty-four thousand miles in circumference. Now the earth turns on its own axis, spins round, these twenty-four thousand miles, going from west to east, in precisely twenty-four hours. Well, sir, that is at the rate of one thousand miles an hour.

Now suppose that I sail from this position a thousand miles east. Of course, I anticipate the rising of the sun here at London by just one hour. I see the sun rise one hour before you do. Proceeding in the same direction yet another thousand miles, I anticipate the rising by two hours; another thousand, and I anticipate it by three hours: and so on, until I go entirely round the globe, and back to this spot, when having gone twenty-four thousand miles east, I anticipate the rising of the London sun by no less than twenty-four hours; that is to say, I am a day in advance of your time. Understand?

But Captain Pratt, when he had sailed a thousand miles west of this position, was an hour, and when he had sailed twenty-four thousand miles was twenty-four hours, or one day, behind the time at London. Thus, with me, yesterday was Sunday; thus, with you, to-day is Sunday; and thus, with Captain Pratt, to-morrow will be Sunday. And what is more, Mr. Rumgudgeon, it is positively clear that we are all right.

Mr. Rumgudgeon, who had forbidden Kate to marry until there were “three Sundays in a week,” now relents. Too bad for him — the international date line would shortly obviate the problem.