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 by time in London, and to correct the date on the exactly opposite side of the earth, in mid-ocean.

Pretend you are in London at noon, Monday. You are a giant with seven-league boots on. You start around the world westward, traveling as fast as the earth turns eastward. It is noon all the way around. But, as the journey takes twenty-four hours, you get back to London at noon the next day. Now, go around the earth eastward, travelling just as fast as before, against the sun, or in the same direction as the earth. You will meet the sun at noon, when half way around, and in half a day, or twelve hours. You pass the sun and meet it again at noon, in London, twelve hours later. As you had noon-time twice in twenty-four hours, you must count Monday twice. So you lose a day, or have the same day twice in going around the earth eastward, and gain or skip a day in going around westward. When crossing the date line, ships going eastward count the same day twice; westward going ships skip a day to keep their dating correct with London time.

HOW THE SPECTRUM EXPLAINS THE SUN

Do you remember about the wise man—Isaac Newton—who was set to thinking out the law of falling bodies by seeing an apple fall to the ground? He was always curious about common things that everybody saw, but