The Clock That Found the World — What is longitude and how did a clock solve it?

Longitude is how far east or west you are, and for hundreds of years no sailor could measure it — ships guessed, and thousands of men died on rocks they thought were a hundred miles away. This lesson shows you the answer a village carpenter found: if you know what time it is back home, you know where you are. Read the two clocks yourself, place your ship on the map, and sail with John Harrison's watch on the sea trial that finally proved it could be done.