Story book: Navigating like clockwork
In 1707, four ships from a British fleet returning to England struck rocks off the Isles of Scilly. Some 2000 people lost their lives in what is now known as one of the worst naval disasters in history. Bad weather and the mariners’ inability to accurately calculate longitude caused the disaster.
In the years following, the British Parliament established the Longitude Act. The Act included a reward of £20,000 (equivalent to over US$3 million today) for anyone who discovered a practical way of calculating longitude. The Act also established the Longitude Board to choose who would receive the prize money.
Astronomy had provided a means to calculate latitude. Popular thought was that astronomy would similarly provide a means to calculate longitude. Nonetheless, one idea came from a clockmaker, John Harrison. John believed he could design and build a clock which could accurately keep time, and thereby calculate longitude. The Board gave John £500 to build his first clock, H1.
It took John 5 years to build the H1 clock. In 1736, a renowned navigator tested the capabilities of the clock at sea. The navigator was amazed by how accurate the H1 was, and by how accurately he could calculate longitude.
The Board didn’t award John the prize money but asked him to produce a more accurate clock. Again, they gave him a small amount of money to do so.
Over 17 years, John built H2, but the Board never tested the clock. An astronomer had proposed a ‘lunar distance model’ to the Board, so John’s work was sidelined. Over 40 years, John produced H3 and H4 clocks.
In 1773, John’s son petitioned the King. He asked him to recognise his father’s life work. The King soon realised that John had solved the longitude problem years before. The Board soon after paid John the full reward.
Today, we still use John’s methods for calculating longitude.