By Jason Parkhill, March 2013

John Harrison portrait by Thomas KingJohn Harrison was one of several individuals such Isaac Newton, Robert Hook, and Edmond Halley that lived in 17th to 18th century England and made significant contributions to science and engineering. Harrison invented the first marine chronometer that enabled ship navigators during the Age of Sail to accurately fix their longitude (east-west) location. This development dramatically improved the safety and precision of long distance travel by sea. Harrison developed and refined his chronometer over decades and eventually claimed the prize that the British Parliament had established in the Longitude Act of 1714 to encourage a development of a device to determine a ship’s longitude at sea. Harrison did all of this without the benefit of a formal education nor an apprenticeship as a clockmaker.

Sobel (2007) explains that, when at sea, the navigator of a ship may fairly easily tell where they are north and south on the Earth. Because the equator is fixed and the earth moves so that the sun shines overhead in a set pattern between the Tropics of Cancer and Capricorn, determining latitude it is a fairly straightforward matter of observing the length of the day or the height of the sun or certain guide stars above the horizon. The zero-degree meridian of latitude is locked in by the laws of nature. Longitude, on the other hand, is not.

The Earth as spinning a sphere can be divided into 360 degrees of longitude. Since it takes twenty-four hours for the Earth to complete one revolution of 360 degrees, one hour equals one twenty-fourth of a spin or fifteen degrees east or west. So in a very meaningful sense, longitude is relative time. An answer to the problem was known but there was no technology to solve it. This seemingly intractable problem of determining longitude could be easily solved by any two cheap mass-produced wristwatches today. To determine longitude, the ship’s navigator must know the time in two places simultaneously. He needs to know the time at his home port and the local time on the ship. Each day when the local noon time was determined on the ship by observing that the sun had reached its high point, the navigator could reset the local clock to noon and compare it to the time on the other clock still set to the time at the port of origin. Each hour difference equaled fifteen degrees of longitude traveled. At the equator fifteen degrees equals a thousand miles and north and south from there the mileage of each degree decreases as you approach the poles. But because latitude is easy to determine, the navigator just needs to make the requisite calculations.

With more sailing vessels setting out on exploration expeditions or moving around treasure from conquered land or to move men and material to lands to conquer, being unable to to accurately and reliably determine whereabouts was a serious problem. Ships frequently ran aground when their intended destinations ended up being closer than expected. On October 22, 1707 near the southern tip of England, four returning British warships ran aground killing around two thousand men in one incident alone.

The search for a solution to the problem of longitude played out over four centuries and involved heads of state, famous astronomers, renowned explorers, and other schemers. The British government established the Board of Longitude in 1714 because:

“The Discovery of the Longitude is of such Consequence to Great Britain for the safety of the Navy and Merchant Ships as well as for the improvement of Trade that for want thereof many Ships have been retarded in their voyages, and many lost…” [and there will be a Longitude Prize] “for such person or persons as shall discover the Longitude” (“History of Longitude,” 2013).

Under the terms of the prize, one would collect £20,000 for determining longitude, as described by King in Andrewes (1996) “to within 30 miles during a voyage from England to the West Indies” (p. 168).

Even though the clock solution was known, the problem persisted well into the age of pendulum clocks. On the deck of a ship in motion, these clocks were entirely unreliable. The would slow down or speed up. As the ship moved from warmer to cooler climates, the lubricating oil crucial for their operation would thin and thicken. Metal parts would expand and contract with temperature changes and even minor variations in the Earth’s gravity would wreak havoc on them. What was needed was an different kind of time-keeping technology.

John Harrison was born in 1693 and was brought up in Barrow upon Humber, a village in north Lincolnshire in the east of England. Like his father, he was raised to be a joiner and this was why his early timepieces were made from wood. He received only a basic education but demonstrated an inquiring mind. In his youth he was lent a copy of notable lectures on Newtonian philosophy of which he made a personal copy. He was interested in music and led the choir and became a bell-ringer at the Church of the Holy Trinity in his village. Bell ringing caused him to become interested in oscillator theory in 1713 and that was also the year he made his first clock (Andrewes, 1996).

Between 1713 and 1730, Harrison produced eight clocks but he was first and foremost employed as a joiner. With each new wooden clock, he refined the winding mechanism and altered the escapement mechanism to reduce recoil and lower friction. His clocks gained a reputation and in 1722, Harrison received a commission to create a turret clock for a large nearby estate marking a big step in his rise as a clockmaker.

During the summer of 1730, at age 37, Harrison traveled to London to gain support for his proposal to make a sea clock. During this trip, Harrison met George Graham, a renowned clockmaker. Harrison said they debated topics for hours as noted in Andrewes (1996):

…we reasoned the cases, or upon the principles, more than once; nay once, and that in a very extraordinary manner, was at the very first time I saw him, and our reasoning, or as it were sometimes debating, (but still, as in the main, understanding one another very well) then held from about ten o’clock in the forenoon, ‘till about eight at night (p. 182).

Harrison wrote about the results of his first sea clock in 1730. This model referred to as H1. Harrison predicted it would be very precise “in the ships they shou’d vary 4 or 5 seconds a month” (Andrewes, 1996, p. 196). H1 contained many clever innovations to stabilize the timekeeping mechanisms on a rocking ship but after testing at sea, revealed defects only solvable by creation of a new clock.

Harrison’s second sea clock, H2, was clearly a refined version of his first. Instead of a cord for winding, it had a key and a sophisticated stopwork to prevent overwinding. He introduced different materials that reacted differently to heat and cold to compensate for effects on springs and escapement. H2 was completed in 1739 but never tried at sea because of members of the Board of Longitudes’ concerns about its design. Harrison also had misgivings after discovering during an experiment that the oscillation of H2’s balances could be affected by centrifugal force.

It was not until 1757 that Harrison completed H3. Several of his supporters had died by this time and the reputation he earned with H1 was fading. Harrison was not able to secure a trial for H3 but it was during the 1750s that Harrison took a break from his clocks to design a pocket watch for his personal use. It was this design that ended up guiding H4.

According to Randall in Andrewes (1996) The pocket watch allowed Harrison “a fresh approach to the whole problem he was facing” (p. 236). Until then, Harrison had focused on what most people considered a clock for longitude — a big stable device for a ship. This turned out to be part of the problem. The Board of Longitude saw the very mobile and “strikingly handsome silver watch” (Quill 1966, p.78) H4 for the first time on July 18, 1760 and by the following year it was ready for testing. Harrison sailed for Jamaica on November 18, 1761. As they approached Jamaica, Harrison told the captain one afternoon that they would spot land the following day at 10:00 AM. They spotted it only 3 hours sooner than expected. John Harrison had come within half a degree in plotting their longitude. It took a second trial by his son William and some further wrangling with the Board but Harrison was awarded the prize money.

Harrison’s life played out in courses similar to those Gardner describes in Sternberg (1998) but maybe not exactly ten year intervals. As stated by Policastro and Gardner in Sternberg, Harrison certainly generated “creative work in the context of prolonged, meaningful, and intrinsically motivating pursuits” (p. 215). It is also easy to see the process described in Ward et al. of the “synthesis and merging of previously separate concepts as being crucial” (p. 202) to Harrison’s success with H4 (combining his sea clock and pocket watch ideas).

References:

Andrewes, W. J. H. (Ed.). (1996). The quest for longitude: the proceedings of the Longitude Symposium, Harvard University, Cambridge, Massachusetts, November 4-6, 1993. Collection of Historical Scientific Instruments, Harvard University.

History of Longitude. (n.d.). In Wikipedia. retrieved February 2, 2013 from
http://en.wikipedia.org/wiki/History_of_longitude

Quill, H. (1966). John Harrison: The man who found longitude. John Baker.

Sobel, D. (2007). Longitude: The true story of a lone genius who solved the greatest scientific problem of his time. Walker & Company.

Sternberg, R. J. (1998). Handbook of Creativity. Cambridge University Press.