Task: Question Answering
Input (English): Context: Greenwich is on the River, five miles from the middle of London, and its history is two thousand years old. The first English people were fishermen there, and they named the place Greenwich, meaning "green village". Later the English kings and queens lived at Greenwich in their beautiful places. The name of the earliest palace was Placentia. Henry VIII lived there. He knew that England must be strong at sea. So he started two big ship-yards at Greenwich. But trouble was coming to Greenwich. In 1649, a war started in England and for eleven years there was no king. The men who had worked for him at Placentia decided to live the place themselves. They sold all its beautiful things. Finally, the war ended and King Charles II came back. But Placentia was falling down. So King Charles built a new and bigger palace, which is now open to the public. At this time, Charles was worried about losing so many of its ships at sea: their sailors did not know how to tell exactly where they were. So in 1675, Charles made John Flamsteed, the first astronomer in England, try to find the answer. Flamsteed worked in a new building on the high ground in Greenwich Park. From it with a telescope which he made himself, Flamsteed could look all round the sky. And he did, night after night, for twenty years. Carrying on Flamsteed's work a hundred years later, an astronomer called Harrison finally made a clock which told the time at sea, and helped sailors to know where they were. You can see Harrison's clock, still working, in Greenwich's museum of the sea. Because of Flamsteed's work, every country in the world now tells its time by Greenwich Time. 
 Question: Who made the first clock which could tell the time at sea?
Output (English): harrison