Day 120. Greenwich, England.

Visited the Old Royal Observatory. The Royal Observatory was moved to Cambridge in 1988. This is where the method for finding longitude was established. In 1714, the British government offered a 20,000 British pounds reward (worth more than $1M today) for anyone who could find a "practical and useful" method to determine longitude at sea because ships constantly went to incorrect destinations. (This is why many countries were discovered.)  John Harrison, a clock maker,  spent the next 45 years developing sea clocks that could keep time correctly.  From this, longitude calculations were developed.  Harrison's H-1 through H-4 were displayed here.もっと詳しく