John Harrison and The Invention of the Chronometer

Alarm Clock Blog - John Harrison & The Invention of the Chronometer

The chronometer is an instrument that accurately measures time.

The first one invented was a marine chronometer, and it was created out of the necessity to have an accurate timekeeper for sea travel. John Harrison, a British clockmaker, invented this device in 1737.

Harrison decided to address the problem of finding longitude during sea travel. Longitude is an imaginary angular line that describes the location of any place on Earth east or west of a north to south line known as the prime meridian. The time difference works out to be one hour for every 15 degrees longitude. This means that each degree of longitude is equal to four minutes.

Marine chronometers enabled ship navigators to find longitude when land was no longer in sight. Although longitude had always been simple to find by means of celestial observations, it was difficult to predict the correct local time at any given destination by using this method.

Harrison set out to solve the problem of finding longitude in a direct way. He produced a reliable clock that kept the time of any given place across a long sea journey. Producing such a clock was difficult because the conditions during sea travel varied. The temperature, pressure and humidity changes would surely cause problems for any timekeeping instrument.

Leading scientists such as Newton and Huygens had doubts that such a clock could ever be built. They were much more optimistic about astronomical observations such as the method of lunar distances. Huygens decided to run trials using both a spring and a pendulum clock as possible methods to determine longitude. Although both clocks showed promising results, they were both known to be problematic for sea travel.

The invention of the chronometer was a fundamental building block for modern times. But the marine chronometer was then redesigned by John Arnold. He based his design on Harrison’s clock, but he simplified it enough to produce accurate marine chronometers in large quantities during the late 1700s. He also made them more cost effective.

Early chronometers were rare and expensive. Their adoption and use began slowly because precision manufacturing was a necessity. The expiration of Arnold’s patents at the end of the 1790s allowed other watchmakers to make chronometers in even greater quantities. By the early part of the 19th century, navigation at sea required a chronometer for safety. Using a chronometer to navigate a ship saved both lives and ships.

The First Three Marine Chronometers

Although an Englishman named Henry Sully had already constructed a marine clock that would determine longitude, it only worked during calm seas. This rendered it useless for the large sea vessels of the time period. However, Sully’s clocks were important because they were among the first attempts to find longitude through the use of a clock. It isn’t coincidental that Harrison’s clocks are of similar design. However, Harrison’s clocks were much larger than Sully’s clocks.

In 1730, Harrison created a sketch and a description of a proposed maritime clock so that he could compete for a monetary prize. He traveled to London to seek financial assistance. His ideas were presented to the Astronomer Royal who introduced him to George Graham, the country’s leading clockmaker. Graham must’ve been quite impressed by Harrison’s plans because he personally loaned Harrison money to build the clock.

It took Harrison approximately five years to build the first clock (!). In 1736, he sailed to Lisbon on the HMS Centurion and returned on the HMS Oxford. On his return trip, the ship’s crew endorsed his clock.

H2 Chronometer by John Harrison

John Harrison’s H2 Chronometer

Harrison ceased production of his second clock because he discovered a design flaw in the balance bars. He failed to recognize that the oscillations of the balance bars would be affected by the pitching motion of a ship. This discovery led him to adopt a circular balance in the third clock. Harrison was granted additional money to develop the clock.

H3 Chronometer by John Harrison

John Harrison’s H3 Chronometer

Harrison spent 17 years working on the third clock, but it did not perform as well as he had imagined. Nevertheless, it was quite a valuable experiment. Clocks one and two failed because the bar balances did not vibrate quickly enough to establish stability. In 1750, Harrison abandoned the idea of these clocks as timekeepers. He realized that a watch would be more successful because it could incorporate balance, and it would have the ability to oscillate at a much higher speed.

Harrison’s First Marine Watch

Harrison called his first marine watch a sea watch. It was rather large, and it was housed in a silver case measuring 5.2 inches in diameter. The movement was highly complex, but it resembled the conventional movement of the time period. This watch took six years to construct, and he sent it on its trial run in the care of his son in 1761. Although the watch was accurate, there was another trial ordered to prove its accuracy. It seems Harrison had some problems with the local officials. Despite the accuracy of his watch, it failed to impress them. This was largely due to the fact Harrison had a few enemies who were now officials.

H4 Sea Watch Chronometer by John Harrison

John Harrison’s H4 Chronometer – The Sea Watch

Harrison then began work on his second sea watch, which was later named H5, and he eventually bypassed the officials by seeking the aid of King George III. King George tested the watch himself over a 10-day period, and he found it to be accurate by a third of a second per day. Captain James Cook also found the watch to be highly accurate. He used one of Harrison’s watches for a voyage and praised the accuracy of the watch. This is undeniable proof the previous problems officials had with his watch were probably invented because of personal rifts. Fortunately, this didn’t prevent Harrison from accomplishing his goal.

Subsequent History of Harrison’s Maritime Chronometers

After World War I, many of the marine chronometers created by Harrison were rediscovered. They were in terrible shape, but they have been restored. The watches are now on display at the National Maritime Museum of the Royal Observatory in Greenwich.

Chronometers are no longer used to calculate longitude for sea travel. They have been replaced over the years by many methods. Much like, the latest method relies on a computer system to calculate time.

Seafaring Meme

As you can see, the chronometer had to be perfected over years of testing, and it was one of the fundamental building blocks to measure time for sea travel. If he were around today, Harrison would be amazed at what has developed to measure time since his inventions. John Harrison died on his 83rd birthday. He is buried at St. John’s Church in Hampstead alongside his wife and son. His tomb was restored in 1879 by the Worshipful Company of Clockmakers. Ironically, he was never a member of this organization. However, they certainly must’ve respected his work. We believe that is as it should be. After all, he did save a lot of lives and a lot of ships with the invention of an accurate marine chronometer. salutes John Harrison as one of the fathers of timekeeping. His efforts led to the safe travel by sea that we have come to expect in modern times.

Before you close your eyes tonight, set one of our alarm clocks so that you can wake up on time for work or school in the morning. Later, you might even be lucky enough to dream of standing on the deck of one of those old ships with the sails puffed and strained by the wind. You might even smell the salty sea air pass through your nose while you glance over the waters searching for a pirate or two. If you do get caught up in a wild dream involving an old sea voyage, will be there to gently wake you up in the morning.

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