Time-telling tools are everywhere these days. Think about the number of mobile devices, clocks on computer sidebars and car radio displays you see before lunch on any given workday; there are plenty of ways to stay on top of the time, it seems.
But there’s something about the face of an elegant wristwatch that just can’t be duplicated in LEDs, liquid crystal or pixels. The three-handed watch face has served centuries’ worth of explorers, businesspeople and users who simply want to mix high style with punctuality.
Of course, that’s not to say that watch aficionados will tolerate lesser accuracy for the sake of a pretty piece of wrist jewelry. A watch is a tool first and foremost, and its ability to display reasonably accurate time is the key feature that differentiates it from a mere bangle. Some die-hards may stick to manual-wind watches or their automatic-watch cousins, citing the intricate beauty of their tiny mechanisms and the smooth sweep of their second hands as signs of high class, but most watch-wearers expect the relatively better accuracy and ease of use that come from a watch equipped with a quartz crystal movement.
A number of manufacturers have tried to combine the smoothness of a mechanical watch movement with the precision of the quartz crystal mechanism: Seiko’s Spring Drive mechanism marries mechanical power with electronic regulation, while Citizen’s Eco-Drive adds solar power and a tiny kinetic generator to the mix. But watchmaker Bulova took a different path in 2010 when it released its Precisionist mechanism: The company claims that this advanced take on quartz watch technology has raised the bar, creating the most precise watch to feature a continuous-sweep second hand [sources: Bulova; Seiko; DiFranco].
Bulova claims that the Precisionist strays from true accuracy 10 seconds or less per year, far better than the 15 seconds per month the company claims is standard for most quartz watches [source: Bulova]. But is that true? Does the Precisionist live up to the billing as a class-leading piece of technology? And how does this unique mechanism eke both smooth movement and high precision out of a quartz crystal mechanism? Take a few minutes to read on; it’ll be well worth your time.
Some Background on Time and Timepieces
Before we dive into the question of accuracy, let’s take a second to get philosophical. Time measurement, after all, is something of an arbitrary construct. The seconds, minutes and hours we use to track duration are basically agreed-upon standards that humankind has employed to represent our march from the past into the future. Existence would not stop if we chose to stop tracking time in such a precise matter — we could function just fine if our main time measurement consisted of sunrise, sunset and the position of the sun in between. A deep dive into the nature of time digs into such sticky wickets as multidimensionality, time travel and the nature of the universe. But for those of us inclined toward more concrete discussions, timepieces offer a more manageable topic [source: Biba].
Somewhere along the line, our ancestors decided that it was useful to track measured units of time. It may have been a pre-Egyptian noble or scholar who first noticed the steady march of shadows on a sunny day, but sundials — the earliest timepieces — have been recovered from archeological sites dating back to 800 B.C. [source: Gascoigne].
Modern watches and clocks work using principles that first came into widespread use in the middle of the 17th century: A resonator, which is a device such as a pendulum, spring-driven flywheel or electrified quartz crystal, oscillates, which means it vibrates or swings back and forth at a consistent, measurable rate. A timepiece will use gears, cams, electric circuits or a combination thereof to translate that oscillation into the measured movement of the clock’s hands or a digital readout of the time [sources: Gascoigne, DiFranco].
For example, a grandfather clock may have a pendulum designed to swing from one side to the other every second. That motion momentarily releases a spring in the clock’s mechanism, allowing the second, minute and hour hands to progress by their respective distances around the clock face. Suppose, now, that your clock has a pendulum that swings every half-second, doubling its oscillation. Your clock can now track half-seconds, giving the hands a smoother motion and allowing you to adjust it with a finer degree of precision. Take this concept, replace the pendulum with an object that oscillates at an extremely high frequency — multiple times per second — and you have the makings of a modern timepiece.
How precise can clocks be?
High-end watches can vary in accuracy depending on their mechanisms. Watch manufacturer Seiko claims its Spring Drive — an electrically adjusted automatic mechanism — varies by no more than one second per day, for example. Breitling, which markets its watches as pinnacle-of-performance timepieces for aviators and sailors, bills its automatics as meeting the Swiss Official Chronometer Testing Institute (COSC) standard for daily variation: no more than four seconds fast or six seconds slow per day. Quartz watches — even relatively inexpensive ones — can be expected to vary or drift by one second or less over the course of 24 hours [source: Lombardi PLEASE LINK TO LMI].
The Bulova Precisionist has a claimed accuracy of 10 seconds of variation per year, drifting less in one month than a decent quartz watch might vary in a day. That may sound very accurate, and may be totally acceptable for most users. But wristwatches as a whole can’t hold a candle to the mother of all accurate timekeepers: atomic clocks.
Forget pendulums; these precision machines use a variety of methods to measure the inherent oscillation of individual atoms. Working as tiny resonators, atoms vibrate at extremely high frequencies; Cesium atoms, for example, resonate at 9,192,631,770 hertz, or cycles per second. Atomic oscillation is also very consistent: Researchers behind a London-based clock using the so-called Cesium fountain process say that their machine is accurate to within two 10 million billionths of a second. Granted, the clock suffers from the inherent problem with atomic clocks from a consumer standpoint: they’re large, sterile arrays of chambers, tubes, wires and scaffolds — not something that would look nice on your wrist, and not exactly an affordable item available at the corner drugstore [source: Loftus]. But it’s nice to know the gold standard when you’re talking about time. (Learn more about atomic clocks in our article, How Atomic Clocks Work.)
The Bulova Precisionist is nowhere near as accurate as an atomic clock, but it does hold its own against other wristwatches in its price range. Read on to learn how the watchmaker squeezes this level of precision out of what is essentially an accurized quartz movement.
For more Detail: How the Bulova Precisionist Works