Exactly: How Precision Engineers Created the Modern World. Simon Winchester

was to display the hours and minutes of the passing days, it remains one of the eccentricities of the period (from our current viewpoint, that is) that time itself first played in these mechanisms a somewhat subordinate role. In their earliest medieval incarnations, clockwork clocks, through their employment of complex Antikythera-style gear trains and florid and beautifully crafted decorations and dials, displayed astronomical information at least as an equal to the presentation of time. It was almost as though the passage of celestial bodies across the heavens was considered more significant than the restless ticking of the passage of moments, of that one-way arrow of time that Newton so famously called “duration.”

      There was a reason for this. Nature’s offerings of dawn, midday, and dusk already provided the temporal framework—the mundane business of when it was time to rise and work, when came the time to rest, to mop the brow and take a drink, and when the time to take nourishment and prepare for sleep. The more finicky details of time (a man-made matter, after all), of whether it was 6:15 a.m. or ten minutes to midnight, were necessarily of lesser importance. The behavior of the heavenly bodies was ordained by gods, and therefore was a matter of spiritual significance. As such, it was far worthier of human consideration than our numerical constructions of hours and minutes, and was thus more amply deserving of flamboyant mechanical display.

      Eventually, though, the reputation and standing of the hours and minutes themselves did manage to rise through the ranks, did come to dominate the usage of the clockwork mechanisms that became known, generically, as timekeepers. The Ancients may have looked upward to the skies to gather what time it was, but once machinery began to perform the same task, a vast range of devices took over the duty, and has done so ever since.

      Monasteries were the first to employ timekeepers, the monks having a need to awaken and observe in some detail the canonical hours, from Matins to Compline by way of Terce, None, and Vespers. And as various other professions and callings started to appear in society (shopkeepers, clerks, men of affairs bent on holding meetings, schoolteachers due to instruct to a rigid schedule, workers on shifts), the need for a more measured knowledge of numerical time pressed ever more firmly. Toilers in the fields could always see or hear the hour on the distant church clock, but city dwellers late for a meeting needed to know how many minutes remained until the “appointed hour” (a phrase that gained currency only in the sixteenth century, by which time public mechanical clocks were widely on display).

      On land, it was the railways that most prolifically showed—one might say defined—the employment of time. The enormous station clock was more glanced at than any other feature of the building; the image of the conductor consulting his (Elgin, Hamilton, Ball, or Waltham) pocket watch remains iconic. The timetable became a biblically important volume in all libraries and some households; the concept of time zones and their application to cartography all stemmed from railways’ imprint of timekeeping on human society.

      Yet, before the chronological influence of railways, there was one other profession that above all others truly needed the most precise timekeeping. It was that which had been developing fast since the European discovery of the Americas in the fifteenth century and the subsequent consolidation of trade routes to the Orient: the shipping industry.

      Navigation across vast and trackless expanses of ocean was essential to maritime business. Getting lost at sea could be costly at best, fatal at worst. Also, because the exact determination of where a ship might be at any one moment was essential to the navigation of a route, and because one part of that determination depends, crucially, on knowing the exact time aboard the ship and, even more crucially, the exact time at some other stable reference point on the globe, maritime clockmakers were charged with making the most precise of clocks.^*

      And none was more sedulously dedicated to achieving this degree of exactitude than the Yorkshire carpenter and joiner who later became England’s, perhaps the world’s, most revered horologist: John Harrison, the man who most famously gave mariners a sure means of determining a vessel’s longitude. This he did by painstakingly constructing a family of extraordinarily precise clocks and watches, each accurate to just a few seconds in years, no matter how sea-punished its travels in the wheelhouse of a ship. An official Board of Longitude was set up in London in 1714, and a prize of twenty thousand pounds offered to anyone who could determine longitude with an accuracy of thirty miles. It was John Harrison who, eventually and after a lifetime of heroic work on five timekeeper designs, would claim the bulk of the prize.

      Harrison’s legacy is much treasured. The curator of the Greenwich Royal Observatory, high on its all-seeing hill above the Maritime Museum to the east of London, comes in each dawn to wind the three great clocks that he and his staff are disposed simply to call “the Harrisons.” He stands on much ceremony to wind them, well aware of the immense historical importance invested in the three timepieces and their one unwound sibling. Each was a prototype of the modern marine chronometer, which, in allowing ships to fix their positions at sea with accuracy, has since saved countless sailors’ lives. (Before the existence of the marine chronometer, before ships’ masters had the ability to determine exactly where they were, vessels tended to collide with importunate frequency into islands and headlands that loomed up unexpectedly before their bows. Indeed, it was the catastrophic collision off the Cornish coast of Admiral Sir Cloudesley Shovell’s squadron of warships in 1707 [which drowned him and two thousand of his sailors] that compelled the British government to think seriously about the means of figuring out longitude—setting up a Board of Longitude and offering prize money—which led, ultimately, to the making of the small family of clocks that are wound each dawn at Greenwich.)

      There were other reasons for the vast importance of the Harrisons. By allowing ships to know their positions and plot their voyages with efficiency, accuracy, and precision, these clocks and their successors enabled the making of untold trading fortunes. And though it may no longer be wholly respectable to say so, the fact that the Harrison clocks were British-invented and their successor clocks firstly British-made allowed Britain in the heyday of her empire to become for more than a century the undisputed ruler of all the world’s oceans and seas. Precise-running clockwork made for precise navigation; precise navigation made for maritime knowledge, control, and power.

      And so the curator pulls on his white curatorial gloves and, using in each case a unique double set of brass keys, unlocks the tall glass-sided cabinets in which the great timekeepers stand. Each of the three is on near-permanent loan from Britain’s Ministry of Defence. The earliest made, finished in 1735 and known these days as H1, the curator can wind with a single strong downward pull on a chain made of brass links. The later pair, the midcentury H2 and H3, require simply a swift turn of a key.

      The final device, the magnificent H4 “sea watch” with which Harrison eventually won his prize money, remains unwound and silent. Housed in a five-inch-diameter silver case that makes it look rather like an enlarged and biscuit-thick version of grandfather’s pocket watch, it requires lubrication and, if it runs, will become less precise with time as the oil thickens; it will lose rate, as horologists say. Moreover, if H4 were kept running, only its second hand would be seen to be moving, and so, as spectacle, it would be somewhat uninteresting—and as a trade-off for the inevitable wear and tear of the movement beneath, the sight of a moving second hand made no sense. So the decision of the observatory principals over the years has been to keep this one masterpiece in its quasi-virgin state, much like the unplayed Stradivarius violin at the Ashmolean Museum in Oxford,^* as an untouched testament to its maker’s art.

      And what sublime pieces of mechanical art John Harrison made! By the time he decided to throw his hat in the ring for the longitude prize, he had already constructed a number of fine and highly accurate timekeepers—most of them pendulum clocks for use on land, many of them long-case clocks, each one more refined than the last. Harrison’s skills lay in the imaginative improvement of his timekeepers, rather than in the decorative embellishment that many of his eighteenth-century contemporaries were known for.

      He was fascinated, for instance, with the problem of friction, and in a radical departure from the norm, he made all his early clocks with wooden gearwheels, which needed none of the lubricant oils of the day, oils that became notoriously more viscous with age and had the trying effect of slowing down most clockwork movements. To solve this problem, he made all his gear trains first