In previous essays we examined the importance of math in the progress of human civilization. One very practical application of math is its use in increasing precision in engineering and manufacturing. So now let’s explore the role of precision more generally in the development of higher technologies, and the unique role a distinctly American culture of pride in precision played in the development of the modern world. Ironically, because it’s so simple to use so much of the high technology around us today, the relentless pursuit of precision that was required to deliver those things to our hands has been increasingly obscured by our devices’ superficial simplicity.
Let’s start this series of essays with a look at how it was precision in the realm of clockmaking that kicked off just about everything we love -- yet likely also take for granted -- in the modern world.
Why clockmaking? Because telling accurate time was essential to travel around the world, which was essential to the sharing of knowledge.
Mapmakers had long divided the globe along horizontal (latitude) and vertical (longitude) lines. For sailors, determining latitude (that is, one’s relative position north and south, between the latitude lines) was relatively easy. That was because, through fluke of circumstance, it turns out the North Star (also called Polaris) is positioned in the sky such that looking at it (in the Northern Hemisphere) will always show you where the northern position on the globe is. Consequently, by using the North Star to create simple triangles with the position of your ship at one apex, a sailor could calculate the relevant angles of those triangles and gauge how far north or south their ship was. A useful video explaining this process can be found here.
However, there are no clearly visible stars like the North Star that appear in the same place over time to show sailors or anyone else where the western or eastern parts of the globe are. So ships, stuck with a reliable means of knowing only where they were north and south, and limited further by the direction the winds and currents flowed, found themselves confined to safely navigating through relatively narrow passageways across the Atlantic Ocean. As Dava Sobel describes in her book Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problems of His Time:
the global ignorance of longitude wreaked economic havoc on the grandest scale. It confined oceangoing vessels to a few narrow shipping lanes that promised safe passage. Forced to navigate by latitude alone, whaling ships, merchant ships, warships, and pirate ships all clustered along well-trafficked routes, where they fell prey to one another.
Consequently, there had to be developed a means of figuring out how far west or east you were on Earth that didn’t rely on the position of any particular star. And it turns out that measuring time would be key to solving that problem.
As Sobel writes:
To learn one’s longitude at sea, one needs to know what time it is aboard ship and also the time at the home port or another place of known longitude -- at that very same moment. The two clock times enable the navigator to convert the hour difference into a geographical separation. Since the Earth takes twenty-four hours to complete one full revolution of three hundred sixty degrees, one hour marks one twenty-fourth of a spin, or fifteen degrees. And so each hour’s time difference between the ship and the starting point marks a progress of fifteen degrees of longitude to the east or west. Every day at sea, when the navigator resets his ship’s clock to local noon when the sun reaches its highest point in the sky, and then consults the home-port clock, every hour’s discrepancy between them translates into another fifteen degrees of longitude … Those same fifteen degrees of longitude also correspond to a distance traveled. At the Equator, where the girth of the Earth is greatest, fifteen degrees stretch fully one thousand miles. North or south of that line, however, the mileage value of each degree decreases. One degree of longitude equals four minutes of time the world over, but in terms of distance, one degree shrinks from sixty-eight miles at the Equator to virtually nothing at the poles.
Sobel continues:
Precise knowledge of the hour in two different places at once -- a longitude prerequisite so easily accessible today from any pair of cheap wristwatches -- was utterly unattainable up to and including the era of pendulum clocks. On the deck of a rolling ship, such clocks would slow down, or speed up, or stop running altogether. Normal changes in temperature encountered en route from a cold country of origin to a tropical trade zone thinned or thickened a clock’s lubricating oil and made its metal parts expand or contract with equally disastrous results. A rise or fall in barometric pressure, or the subtle variations in the Earth’s gravity from one latitude to another, could also cause a clock to gain or lose time.
So while a sailor could always reset his own ship time to noon each day by oberving the sun when it was directly above, it was essential to also have on board a clock that kept ultra-precise local port time as it traveled on the ship leaving port and beyond, as there would be no other means of double-checking the accuracy of that clock when the sun was directly above at noon way back at port.
The need to develop an accurate clock was spurred by an English navy disaster:
As more and more sailing vessels set out to conquer or explore new territories, to wage war, or to ferry gold and commodities between foreign lands, the wealth of nations floated upon the oceans. And still no ship owned a reliable means for establishing her whereabouts. In consequence, untold numbers of sailors died when their destinations suddenly loomed out of the sea and took them by surprise. In a single such accident, on October 22, 1707, at the Scilly Isles near the southwestern tip of England, four homebound British warships ran aground and nearly two thousand men lost their lives.
That incident caused Parliament to enact the Longitude Act of 1714, in which the English government promised a prize of £20,000 for a solution to the longitude problem. Spurred by this potential reward, a man named John Harrison, an amateur astronomer, and his son went on to create the most accurate clock in the world. Harrison:
tested the accuracy of their gridiron-grasshopper clocks against the regular motions of the stars. The crosshairs of their homemade astronomical tracking instrument, with which they pinpointed the stars’ positions, consisted of the border of a windowpane and the silhouette of the neighbor’s chimney stack. Night after night, they marked the clock hour when given stars exited their field of view behind the chimney. From one night to the next, because of the Earth’s rotation, a star should transit exactly 3 minutes, 56 seconds (of solar time) earlier than the previous night. Any clock that can track this sidereal schedule proves itself as perfect as God’s magnificent clockwork. In these late-night tests, the Harrisons’ clocks never erred more than a single second in a whole month. In comparison, the very finest quality watches being produced anywhere in the world at that time drifted off by about one minute every day. The only thing more remarkable than the Harrison clocks’ extraordinary accuracy was the fact that such unprecedented precision had been achieved by a couple of country bumpkins …
The prime innovation of the Harrison clock can still be found today inside thermostats and other temperature-control devices:
It is called, rather unpoetically, a bi-metallic strip [which] compensates immediately and automatically for any changes in temperature that could affect the clock’s going rate. Although Harrison had done away with the pendulum in his first two sea clocks, he had maintained gridirons in their works, combining brass and steel rods mounted near the balances to render the clocks immune to temperature changes.
A bimetallic strip works by fusing together two metals that expand and contract at different rates, so when the temperature changes, part of the strip bends one way, but the other part of the strip bends the opposite way, thereby maintaining the straightness of the strip no matter what the temperature. This innovation and many others in the Harrison clock so impressed the Royal Society that it recommended “it highly deserves Public Encouragement” and “a thorough Trial” of “the several Contrivances, for preventing those Irregularityes in time, that naturally arise from the different degrees of Heat and Cold, a moist and drye Temperature of the Air, and the Various Agitations of the ship.”
The trials were a success, with the Harrison clock on one voyage losing only five seconds of time after 81 days at sea. The clock was even tested on the ship the H.M.S. Beagle, which also brought Charles Darwin to the wildlife he studied on the Galapagos Islands.
As Sobel writes:
For decades [Harrison] had stood apart, virtually alone, as the only person in the world seriously pursuing a timekeeper solution to the longitude problem. Then suddenly, in the wake of Harrison’s success with [one of his clocks] legions of watchmakers took up the special calling of marine timekeeping. It became a boom industry in a maritime nation. Indeed, some modern horologists claim that Harrison’s work facilitated England’s mastery over the oceans, and thereby led to the creation of the British Empire -- for it was by dint of the chronometer that Britannia ruled the waves.
Harrison’s clock was fantastic, but exorbitantly expensive, and available only to national governments. That is, until thousands of clock tinkerers around the world competed to bring the size and price of clocks down, putting them into the hands of everyday citizens, as will be explored in the next essay.
The Dara Sobel book is one of the best I havevever read