|Scilly Isles disaster of 1707 from 18th century print|
Kensington Row Bookshop to discuss Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time by Dava Sobel. The book was chosen to honor Cliff Lanham, a long-time member of the club who died last year. He was a world expert on technology transfer, and had often encouraged the club to choose books on the history of technology.
The book is basically the story of John Harrison and his son William who in the 18th century advanced the craft of watch and clock making, eventually producing a marine chronometer that was judged by Parliament as worthy of a major financial reward for the development of a means of measuring longitude at sea.
It was possible at the time to determine latitude by siting of the north star or the sun. Determination of latitude, which required determination of the difference in time between one's location and that of a known place, was not possible as it was beyond the clock makers ability, Two alternatives standard time -- observation of astronomical events that would be seen at the same moment over half the earth, or development of clocks capable of keeping accurate time over an entire voyage.
Scilly Isles, leading to the death of some 2000 men. This was but the worst of many disasters at sea due to mistakes in the estimated longitude of ships. Many of the European countries, as long distance voyages became more common, sought to encourage the development of accurate means of keeping time at sea. In 1714, the British Parliament established a prize for the first to establish a practical means of measuring longitude at sea -- 20,000 pounds if the longitude could be determined accurately to within a half degree. The Longitude Commission, staffed by a distinguished group of scientists and naval officers, was charged with implementation of the law.
John Harrison, who had successfully built some wooden clocks for his local customers, In 1730 he designed the first in a series of clocks that he believed would be sufficiently accurate to win the prize. He was referred by Edmond Halley to England's most prestigious clock maker, George Graham, who was impressed by Harrison's ideas and who provided him with support to develop the clock. It took five years to build the clock, and in 1736 it was given a sea trial on a round trip to Lisbon, the first clock to have a trial approved by the Committee. The clock appeared successful on that voyage, and a trial on a longer voyage was authorized.
Harrison, however, chose to build a second clock rather than go ahead with the proposed longer trial. He abandoned that design when it proved not to retain the necessary accuracy when subjected to the pitching action of a ship at sea. Harrison then spent 17 years working on a third clock. He came to believe that a smaller device would be required to achieve the accuracy and reliability, and to be practical for manufacture to meet the demand.
|Harrison's Sea Watch #1|
5.2 inches in diameter
A second voyage was made, and the watch again met the criterion. In that voyage it was compared with an astronomical measurement proposed by Nevil Maskelyne. The Maskelyne approach in the head-to-head comparison was less accurate and appeared to require long and difficult calculations. However, before the prize was awarded, Maskelyne was appointed Astronomer Royal, and thus ex officio, chair of the Longitude Committee. The prize was not awarded.
Harrison then began to work on a second sea watch, his fifth device. When it was completed, however, he had the help of King George III in testing its accuracy. The King also provided help in bypassing the Longitude Committee and going directly to the Parliament which awarded Harrison £8,750 in 1773; John Harrison was then 80 years old. The prize was never awarded. However, in total Harrison received £23,065 for his work on chronometers, and was a wealthy man in his old age. Over his lifetime he made a number of inventions improving the accuracy of clocks and watches.
We noted too that negative information from "outsiders" is sometimes ignored; indeed, in the Scilly Isles tragedy mentioned above, a sailor had warned the admiral in charge that according to his, the sailor's reckoning they were about to go aground. The sailor was hanged, as it was a capital crime for a seaman to keep track of a ships position.
We also noted that the class distinctions in England are hard for an American to fully appreciate, and that they would have been much greater in the 18th century than today. A small town carpenter would have been of a much lower class than the scientists of sufficient prestige to be named to the Longitude Committee, or indeed than the senior officers of the navy on the Committee. The class prejudice might have acted in such a way that the Committee failed to properly appreciate Harrison's ideas.
We also thought that the scientists were much more likely to consider the astronomical approaches, which were cutting edge science of the day, to be effective, rather than an approach based on clockwork. It was noted that the naval officers seemed much more positive about Harrison's clocks, especially those who had seen them in use on voyages. James Cook used a copy of Harrison's first sea watch on two of his voyages and was very positive about its utility.
We noted that a captain of one of the ships used on a test voyage asked to be placed on the list for one of the first Harrison chronometers on sale; indeed once marine chronometers became commercially available in the 19th century, many sea captains purchased their own. On a tangent, we noted that long after Harrison died, sea captains regularly brought their own marine chronometers on board their ships, and that ships at sea had several of the expensive devices, not willing to take the chance of a single chronometer stopping, leaving them without a means of knowing the exact time.
The astronomers were also partly right. Measurement of time by astronomical observation was used in surveying on land. It was effective in establishing the longitude of ports, for example. Indeed, astronomical determination of longitude was used by Zebulon Pike (of Pike's Peak fame) in his survey of the American west in the early 19th century.
However, we contemplated also the idea that Maskelyne might have wanted the prize money for himself, and was not a fair judge. Indeed, a member suggested that it is hard to avoid conflict of interest in committees that make technological judgments, where members of the committee may well know some of the applicants for money (or where their institutions may benefit from grants).
Was the Committee Right? A member noted that one would want more than one test. The clock could be right at the end of the voyage by chance. Or the voyage might itself have been unusual, say unusually calm, leading to a good result that would not be repeated on a rough voyage. Or a clock that often would fail over a long voyage, might not fail on a single test voyage. The facts that Harrison chose not to subject his first clock to a longer test voyage, and that his second clock proved vulnerable to the pitch of the ship, suggests that multiple voyages might indeed be needed to test the practicality of a watch (no matter what the Parliament said in its law).
The Committee also asked that Harrison disassemble his clock while members observed the process. Their interest seems to have been whether the clock could be replicated commercially at an affordable cost. We thought that it might not have met that test. Harrison apparently hand tuned the parts of the device carefully to obtain the required accuracy. When the Harrison clocks were cleaned and put back into operation in the 20th century, one had to be taken apart and reassembled a thousand times before it worked accurately. Indeed, there were elements of the early clocks that represented remnants of experiments that had been tried and failed -- but portions not disturbing other functions simply left in the device.
It was noted in passing that Sobel perhaps failed to do justice in the book to Edmond Halley, who was for part of period covered the Astronomer Royal and chair of the Longitude Committee. As Neil deGrasse Tyson describes in the third episode of the TV series Cosmos, Halley was a very great scientists indeed. Among his many accomplishments was that of convincing Newton to write Philosophiae Naturalis Principia Mathematica documenting the theory of gravity and the invention of calculus; when the Royal Academy failed to publish Principia, Halley did so with his own money.
We noted that by the 18th century, long voyages had become much more common. Marine trade routes had developed from western Europe to Asia and the Americas. (Not to mention down the coast of Africa, and from America to Asia as we read in 1493: Uncovering the New World Columbus Created by Charles Mann. The increase in long distance sea voyaging increased the magnitude of the problems related to failing to measure longitude accurately.
We also noted that sailing south to a given latitude and then sailing east or west to the desired port involved (in theory) traveling two legs of a right triangle, while the voyage via the hypotenuse would be shorter, perhaps much shorter. Long distance voyages by sailing ship took a long time, and were dangerous. If the distance could be shortened and the time cut, money would be saved. It was suggested that the economic benefits of a good way of measuring longitude in the age of sail might have been as important or more important than the military benefits.
And of course, a nation that gained a monopoly on the technology to measure longitude would gain trade and military advantages that would lead to economic and political power. That is why various governments were not only offering rewards for the development of such technology, but doing so on condition that the means would be closely held within the nation,
Developing Technology Capacity: Sobel tells a great story of a lone inventor working for decades alone, unappreciated, to create a new kind of machine that both met an important need and that could be manufactured. According to one member, that is not the way we understand technology to develop.
Clocks had been around for a very long time. Galileo had proposed the pendulum clock early in the 17th century, which was the basis for Harrison's early, accurate wooden clocks. (Incidentally, Galileo also proposed using astronomical observations as a standard for "celestial time".) Watches, albeit of very limited accuracy, had been available in the 17th century, and the watch makers art had advanced. Moreover, there were advances being made in metallurgy, metal working machinery, and the measurement of mechanical devices. One must assume that Harrison benefited from the science of the Age of Enlightenment and the technology of the new Industrial Revolution.
We know that Harrison had financial help from George Graham, and that he discussed his original design with Graham. (He also had contact with Thomas Mudge, Graham's successor.) In 1753, John Jefferys made a pocket watch for Harrison (apparently to keep time as an observer moved from the chronometer kept in a ships cabin to the deck where astronomical observations would be made). An apprentice of Jefferys, Larcum Kendall, made the copy of the Harrison chronometer that Captain Cook took on his voyage. According to Wikipedia, "the marine timekeeper was reinvented yet again by John Arnold who while basing his design on Harrison's most important principles, at the same time simplified it enough for him to produce equally accurate but far less costly marine chronometers in quantity from around 1783. Nonetheless, for many years even towards the end of the 18th century, chronometers were expensive rarities, as their adoption and use proceeded slowly due to the precision manufacturing necessary and hence high expense."
Thus perhaps John Harrison, while contributing many innovations to the marine chronometer, is likely to have built on the work of others, to have benefited from the collaboration with expert watchmakers, and to have had his work actually become commercial due to John Arnold.
The Measurement of Time and Calendars: We left the subject of Sobel's book per se, to talk about time and calendars. For example, a member explained the use of a simple device with two aligned pinholes located at either end of a tube with a crystal at the back pinhole. When the tube is oriented north-south, the sun at midday can pass through the two pinholes and fall on the crystal, making it shine brightly. This device was used before there were accurate clocks to identify noon exactly on shipboard. Indeed, a ten minute warning bell or blast used to be used in ports to alert arriving ships that the measurement could soon be made.
A member also explained the analemma, the figure 8 that is found in the Pacific Ocean on many globes. From earth, the sun appears to move against the celestial sphere over the course of the year, due to the nature of the earth's orbit around the sun. The analemma describes this apparent path. It is also related to the equation of time, which which describes the discrepancy between apparent solar time (measured by tracking the sun) and mean solar time (with noons 24 hours apart).
We also talked about various calendars. The Gregorian calendar, used by most of us today, was promulgated so that Easter Sunday in the Catholic Church's calendar could remain in its original relationship with the Spring equinox. The earlier Julian calendar had defined a year to be slightly longer than the time it takes the earth to orbit the sun. By 1582 when the Gregorian calendar was proclaimed, the Spring equinox had shifted 10 days, so 10 days were simply skipped that year. However, the Gregorian calendar also does not have leap years on years that are divisible by 400. The Jewish and Islamic calendars are lunar rather than solar; the Jewish calendar periodically has a special month to realign the lunar with the solar calenday, the Islamic calendar does not, and the location of its months shift with respect to the seasons over time.
A member also explained the difference between solar time and sidereal time.
The Writing of History: As an aside in the discussion of the book we came again to the question of why so many historians seem to write poorly. There are of course authors, some whom we have read, who write well and know their history, but many seem to have come to a style that is stultifying, Two members present mentioned that they had in graduate school done projects focusing on why historians can't (or at least too often don't) write well. In neither case was the project well received by faculty.
The Bottom Line: This short book was received by the group as a pleasure to read. It read like a feel good novel, with a heroic protagonist overcoming great diversity to triumph in the end. Attracting a wide readership, it acquainted its reader with an important problem of the 18th century age of sail, and how that problem was solved. Its author is not a professional historian, but rather a former New York Times science writer. However, we found that the book failed to put Harrison;s contributions in the context of the science and technology of his time, thereby suggesting a simplistic model of technology development. It perhaps failed to adequately recognize the economic motivation behind the search for a means to measure longitude, the cultural divide underlying Harrison's problems with the Longitude Committee, and the quality of that Committee and its work.