Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time - Dava Sobel (2005)

Chapter 10. The Diamond Time keeper

The cabinet is formed of gold

And pearl and crystal shining bright,

And within it opens into a world

And a little lovely moony night.

—WILLIAM BLAKE, “The Crystal Cabinet”

Rome wasn’t built in a day, they say. Even a small part of Rome, the Sistine Chapel, took eight years to construct, plus another eleven years to decorate, with o Michelangelo sprawled atop his scaffolding from 1508 to 1512, frescoing scenes from the Old Testament on the ceiling. Fourteen years passed from the conception to the completion of the Statue of Liberty. The carving of the Mount Rushmore Monument likewise spanned a period of fourteen years. The Suez and Panama Canals each took about ten years to excavate, and it was arguably ten years from the decision to put a man on the moon to the successful landing of the Apollo lunar module.

It took John Harrison nineteen years to build H-3.

Historians and biographers cannot explain why Harrison—who turned out a turret clock in two years flat when he had scant experience to guide him, and who made two revolutionary sea clocks within nine years—should have lingered so long in the workshop with H-3. No one suggests that the workaholic Harrison dallied or became distracted. Indeed, there is evidence that he did nothing but work on H-3, almost to the detriment of his health and family, since the project kept him from pursuing most other gainful employment. Although he took on a few mundane clockmaking jobs to make ends meet, his recorded income during this period seems to have come entirely from the Board of Longitude, which granted him several extensions on his deadline and five payments of £500 each.

The Royal Society, which had been founded in the previous century as a prestigious scientific discussion group, rallied behind Harrison all through these trying years. His friend George Graham and other admiring members of the society insisted that Harrison leave his workbench long enough to accept the Copley Gold Medal on November 30, 1749. (Later recipients of the Copley Medal include Benjamin Franklin, Henry Cavendish, Joseph Priestley, Captain James Cook, Ernest Rutherford, and Albert Einstein.)

Harrison’s Royal Society supporters eventually followed the medal, which was the highest tribute they could confer, with an offer of Fellowship in the Society. This would have put the prestigious initials F.R.S. after his name. But Harrison declined. He asked that the membership be given to his son William instead. As Harrison must have known, Fellowship in the Royal Society is earned by scientific achievement; it cannot ordinarily be transferred, even to one’s next of kin, in the manner of a property deed. Nevertheless, William was duly elected to membership in his own right in 1765.

This sole surviving son of John Harrison took up his father’s cause. Though a child when the work on the sea clocks began, William passed through his teens and twenties in the company of H-3. He continued working faithfully with his father on the longitude timekeepers until he was forty-five years old, shepherding them through their trials and supporting the elder Harrison through his tribulations with the Board of Longitude.

As for the challenge of H-3, which contains 753 separate parts, the Harrisons seem to have taken it in stride. They never cursed the instrument or rued its long rule over their lives. In a retrospective review of his career milestones, John Harrison wrote of H-3 with gratitude for the hard lessons it taught him: “[H]ad it not been through some transactions I had with my third machine . . . and as to be so very weighty or so highly useful a matter or discovery and as never to be known or discovered without it . . . and worth all the money and time it cost viz my curious third machine.”

One of the innovations Harrison introduced in H-3 can still be found today inside thermostats and other temperature-control devices. It is called, rather unpoetically, a bi-metallic strip. Like the gridiron pendulum, only better, the bi-metallic strip 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. Now, with H-3, he produced this simplified, streamlined strip—of fine sheet brass and steel riveted together—to accomplish the same end.

A novel antifriction device that Harrison developed for H-3 also survives to the present day—in the caged ball bearings that smooth the operation of almost every machine with moving parts now in use.

H-3, the leanest of the sea clocks, weighs only sixty pounds—fifteen pounds less than H-1 and twenty-six pounds lighter than H-2. In place of the dumbbell-shaped bar balances with their five-pound brass balls at either end, H-3 runs on two large, circular balances, mounted one above the other, linked by metal ribbons, and controlled by a single spiral spring.

Harrison had been aiming for compactness, mindful of the cramped quarters in a captain’s cabin. He never considered trying to make a longitude watch to fit in the captain’s pocket, because everyone knew that a watch could not possibly achieve the same accuracy as a clock. H-3, svelte in its dimensions of two feet high and one foot wide, had gone about as far as a sea clock could go toward diminution when Harrison completed the bulk of the work on it in 1757. Although he still wasn’t altogether thrilled with its performance, Harrison deemed H-3 small enough to meet the definition of shipshape.

An odd coincidence—if you believe in coincidences—changed his thinking on that score. What with all the brass work and specialty detailing he required for the longitude timekeepers, Harrison had come to know and contract with various artisans in London. One of these was John Jefferys, a freeman with The Worshipful Company of Clockmakers. In 1753, Jefferys made Harrison a pocket watch for his personal use. He obviously followed Harrison’s design specifications, for Jefferys fitted the watch with a tiny bi-metallic strip to keep it beating true, come heat or cold. Other watches of the time sped up or slowed down by a factor of ten seconds for every one-degree change in temperature. And, whereas all previous watches either stopped dead or ran backward when they were being wound, this one boasted “maintaining power” that enabled it to keep running even through winding.

Some horologists consider the Jefferys timepiece the first true precision watch. Harrison’s name is all over it, metaphorically speaking, but only John Jefferys signed it on the cap. (That it still exists, in the Clockmaker’s Museum, is something of a miracle, since the watch lay inside a jeweler’s safe in a shop that took a direct bomb hit during the Battle of Britain, then baked for ten days under the building’s smoldering ruins.)

This watch proved remarkably dependable. Harrison’s descendants recall that it was always in his pocket. It occupied his mind, too, shrinking his vision of the sea clock. He mentioned the Jefferys watch to the Board of Longitude in June of 1755, during one of his de rigueur explanations of the latest delay attending H-3. According to the minutes of that meeting, Harrison said he had “good reason to think,” on the basis of a watch “already executed according to his direction”—i.e., the Jefferys watch—“that such small machines may be . . . of great service with respect to the longitude.”

In 1759, when Harrison finished H-4, the timekeeper that ultimately won the longitude prize, it bore a stronger resemblance to the Jefferys watch than to any of its legitimate predecessors, H-1, H-2, or H-3.

Coming at the end of that big brass lineage, H-4 is as surprising as a rabbit pulled out of a hat. Though large for a pocket watch, at five inches in diameter, it is minuscule for a sea clock, and weighs only three pounds. Within its paired silver cases, a genteel white face shows off four fanciful repeats of a fruit-and-foliage motif drawn in black. These patterns ring the dial of Roman numeral hours and Arabic seconds, where three blued-steel hands point unerringly to the correct time. The Watch, as it soon came to be known, embodied the essence of elegance and exactitude.

Harrison loved it, and said so more clearly than he ever expressed another thought: “I think I may make bold to say, that there is neither any other Mechanical or Mathematical thing in the World that is more beautiful or curious in texture than this my watch or Timekeeper for the Longitude . . . and I heartily thank Almighty God that I have lived so long, as in some measure to complete it.”

Inside this marvel, the parts look even lovelier than the face. Just under the silver case, a pierced and engraved plate protects the works behind a forest of flutings and flourishes. The designs serve no functional purpose other than to dazzle the beholder. A bold signature near the plate’s perimeter reads “John Harrison & Son A.D. 1759.” And under the plate, among the spinning wheels, diamonds and rubies do battle against friction. These tiny jewels, exquisitely cut, take over the work that was relegated to antifriction wheels and mechanical grasshoppers in all of Harrison’s big clocks.

How he came to master the jeweling of his Watch remains one of the most tantalizing secrets of H-4. Harrison’s description of the watch simply states that “The pallets are diamonds.” No explanation follows as to why he chose this material, or by what technique he shaped the gems into their crucial configuration. Even during the years when the Watch was dissected and inspected by committees of watchmakers and astronomers as it went through the mill of repeated trials, no recorded question or discussion came up regarding the diamond parts.

Lying in state now in an exhibit case at London’s National Maritime Museum, H-4 draws millions of visitors a year. Most tourists approach the Watch after having passed the cases containing H-1, H-2, and H-3. Adults and youngsters alike stand mesmerized before the big sea clocks. They move their heads to follow the swinging balances, which rock like metronomes on H-1 and H-2. They breathe in time to the regular rhythm of the ticking, and they gasp when startled by the sudden, sporadic spinning of the single-blade fan that protrudes from the bottom of H-2.

But H-4 stops them cold. It purports to be the end of some orderly progression of thought and effort, yet it constitutes a complete non sequitur. What’s more, it holds still, in stark contrast to the whirring of the going clocks. Not only are its mechanisms hidden by the silver case enclosure, but the hands are frozen in time. Even the second hand lies motionless. H-4 does not run.

It could run, if curators would allow it to, but they demur, on the grounds that H-4 enjoys something of the status of a sacred relic or a priceless work of art that must be preserved for posterity. To run it would be to ruin it.

When wound up, H-4 goes for thirty hours at a time. In other words, it requires daily winding, just as the big sea clocks do. But unlike its larger predecessors, H-4 will not tolerate daily human intervention. Nay, H-4, often hailed as the most important timekeeper ever built, offers mute but eloquent testimony on this point, having suffered mistreatment at the hands of its own great popularity. As recently as fifty years ago, it lay in its original box, with the cushion and winding key. They have since been lost in the course of using H-4—transferring it from one place to another, exhibiting it, winding it, running it, cleaning it, transferring it again. In 1963, despite the sobering lesson of the lost box, H-4 visited the United States as part of an exhibition at the Naval Observatory in Washington.

Harrison’s big sea clocks, like his tower clock at Brocklesby Park, have more wherewithal to withstand regular use because of their friction-free design features. They embody Harrison’s pioneering work to eliminate friction through the careful selection and assembly of components. But even Harrison was unable to miniaturize the antifriction wheels and the caged roller bearings for the construction of H-4. As a result, he was forced to lubricate the watch.

The messy oil used for horological lubrication mandates scheduled maintenance (and this is as true today as it was in Harrison’s time). As it seeps about the works, the oil changes viscosity and acidity, until it no longer lubricates but merely loiters in interior recesses, threatening to sabotage the machinery. To keep H-4 running, therefore, caretakers would have to clean it regularly, approximately once every three years, which would require the complete dismantling of all parts—and incur risk that some of the parts, no matter how carefully held with tweezers and awe, would be damaged.

Then, too, moving parts subjected to constant friction eventually wear out, even if they are kept lubricated, and then have to be replaced. Estimating the pace of this natural process of attrition, curators suppose that within three or four centuries, H-4 would become a very different object from the one Harrison bequeathed to us three centuries ago. In its present state of suspended animation, however, H-4 may look forward to a well-preserved life of undetermined longevity. It is expected to endure for hundreds of years, if not thousands—a future befitting the timepiece described as the Mona Lisa or The Night Watch of horology.