Our morning breakfast routine with the kids includes several inquiries, imperatives and reminders regarding time. Some of us are ready on time, yet get delayed lingering over the comics or savoring chai, and need to be prodded to look at the clock. Others watch the clock on the phone, the microwave or the car radio, restless to leave or arrive. Few things are as exciting as being early at the bus stop, or greeting the teachers during their morning coffee.
Today, on the way to school, our little time-teller wondered: "How did the first person who made a clock set its time?"
I did not know, so we started thinking this through. The easiest way, as usual, is to respond with a question. In this case: "How did we track time before clocks?"
Within a few minutes, we had covered the movement of the sun, sun-dials, water clocks, hourglasses and talked about Babylonians and their preference for the number 60. Leaving aside the enthusiasm for a sundial project, it took me many more minutes to realize that the question is deeper than the mechanics of how to measure time.
Let's say you have an accurate and highly reliable timepiece. What time do you set it to?
Well, you look at your phone, or hear the time on radio, or tune to the atomic clock in Colorado, or..., but wait, how did the first clock-maker set the time?
It turns out that mechanical clocks have been made for a surprisingly longer time than you would expect. You could observe noon when the sun is directly overhead, set the clock to "12", and then ensure it can track 24 hours to the next noon. For cuckoo clocks and those counting only the hour, this would be reasonably sufficient. But the precision watch maker building minute and second tracking needs astronomical help.
For reasons, mostly to do with earth's oblique axis of rotation and its elliptical orbit around the sun, the Earth's analemma is an asymmetric figure-of-eight, which results in variable duration of the solar day, and changes the "time of noon" from day to day as the year progresses, varying by as much as 30 minutes through the year. Ancient astronomers across diverse continents from America to India knew this, which led to the equation of time.
The real solar time is that shown by the sun-dial. Mechanical clocks cannot easily be built to show that time. Neither does it make sense for them given that their strength is their reliable counting mechanisms. This discrepancy with true solar time became especially noticeable with improvements in the accuracy and precision of clock mechanisms.
It is not surprising then, that Christiaan Huygens, the inventor of the pendulum clock was also the first to publish correct tables for the equation of time. For John Flamsteed, the first Astronomer Royal of Britain, this was part of the job, and he published even more accurate tables for Greenwich, the site of the Royal Observatory.
As an aside, Both Huygens and Flamsteed were Fellows of the Royal Society of London for the Improvement of Natural Knowledge. These and other Fellows combined scientific theory, empirical observations and applied technology to vastly improve time measurement.
As is true of technology to this day, timepieces became better and cheaper and affordable to the common citizen. Timekeeping set the cadence of the Industrial Revolution, changed social customs and transformed how people lived, worked, taught and learned.
All that remained was standardization, which is having the same "time" all across a nation, regardless of local noon. That process was driven by the needs of safe navigation and transportation.
As the leading maritime nation, the British (and Royal Society) were at the forefront of determining ship's position by latitude as well as longitude. Fixing latitude is easy, and had been developed many centuries ago, but a fix for longitude required more than 200 years of concerted efforts and government incentives. The quickest and most reliable method became possible only with the availability of accurate marine chronometers.
Time equals longitude, and knowing the time at a fixed reference point in conjunction with the observed solar local time, ships could fix their longitude. The reference time tracked by ships' chronometers was the time at Greenwich, known as the Greenwich Mean Time. (And conveniently for calculations, the longitude through GMT was Meridian Zero).
But landlubbers remained stubborn in their use of local time, and even on a small island like Britain, there were differences of 15 to 20 minutes in the local time between major cities. This is not a big deal, until you have steam-powered locomotives. Suddenly this small difference can lead to confusion in train schedules. This led to specifying train timetables and setting railway clocks in terms of Railway Time.
The confusion went beyond missed trains. With increase in train speeds and frequency, engineers, conductors and station masters had to develop detailed schedule for train crossings and track switchings. Train operators and railroad employees using different local times would lead to disruptions and accidents. As a result, railroad companies were the first to standardize time across their network, developing technical means and operational methods to synchronize clocks.
The synchronization was facilitated by the growth of communication networks. Telegraph links were usually laid beside railway lines, and soon they were used to electrically transmit time signals from Greenwich. Eventually, the Standard Time (or GMT) was mandated by national law in Britain. The story was repeated wherever railways went, so trains connected people in more ways than one.
Wth air travel and now the Internet, it is routine to hop across dozens of Standard Time Zones within a "day" or coordinate with people across time zones. The zero-hour time zone is a successor of the GMT and referred to as Zulu or Coordinated Universal Time (UTC). The UTC is tracked with a precise atomic clock, and requires leap second adjustments to correlate with the slowing down of earth's rotation. Airplane pilots, military commanders, multi-national companies and worldwide travelers rely on it for safety and punctuality. And life is better for web programmers when all transactions are logged in UTC.
Time is now broadcast by radio waves, embedded into GPS satellite signals and burned into computer firmware, so we don't have to think about how to set the time on some watch. Unless, of course, you are given to wondering or like periodic reminders of the time it took to set time.
(Railway Clock - credit Alex Drennan)
