Perfect time

A history of the word ‘chronometer’, the use of escapements and 18th-century satire

Humpty Dumpty famously says, in Alice in Wonderland, that words are nothing more than pieces in a game, where you can change the rules any time you want. “When I use a word,” he says, “it means just what I choose it to mean — neither more nor less.” To which Alice replies, tactfully if sceptically, “The question is... whether you can make words mean so many different things.” In all of watchmaking, there is probably no word that this applies more to than “chronometer”, which first burst on the scene in 1714 — or so many people think — and has been shape-shifting ever since.

Now, you do not have to spend much time around watches before you figure out pretty quickly that a chronometer is not a chronograph. The latter, of course, is basically a combination of a watch and a stopwatch; the former, at least nowadays, is a watch which — assuming it comes from an ISO-standards compliant country, which Switzerland is — has been certified by an independent examination board and found to meet certain minimum standards.

That officiating body today is the (in) famous Controle Officiel Suisse des Chronomètres, better known to Watch Idiot Savants the world over simply as the COSC. In its current form, the COSC has been around since 1973, but prior to that, testing took place at the so-called Bureaux officiels de controle de la marche des montres, which in horological literature is generally more concisely referred to as the BO agencies. There were different numbers of these at different periods in history: One of the oldest, in Bienne, was founded in 1877. It was these agencies that were responsible for providing independent testing of watches seeking chronometer certification, until they were put under central administration and dubbed the COSC in 1973.

COSC standards for mechanical watches are pretty straightforward. For most watch enthusiasts, the most relevant standard is the one for average daily rate over a 10-day testing period: For a watch to pass, it must maintain an average daily rate of -4/+6 seconds. Rolex used to get flak now and again for calling its watches “superlative” chronometers on the dials, but in 2015, the Crown introduced the new Day-Date 40, along with a new Superlative Chronometer internal certification, requiring a daily rate of -2/+2 maximum per day. In 2016, Rolex announced it would extend this to all Rolex watches.

That is the gist of it for the 20th and 21st centuries. In the 19th century, however, as you go back, you start to see the meaning of the word change as you look further and further back at its usage and evolution.

The chronometer escapement
Girard-Perragaux made a key-wound, high-grade pocket watch for the English market around 1860. One of the technical features of this timepiece is the escapement, which is what is called a detent escapement. The detent escapement was, as far as we know, invented by French horologist Pierre LeRoy in 1748, although the first practical version of the escapement was the pivoted detent escapement of John Arnold in 1775. Arnold’s contemporary in England, Thomas Earnshaw, was responsible for developing the version of the detent escapement that came to be most widely used. The basic layout of the spring detent escapement was shown in the 1896 edition of Britten’s The Watch and Clockmakers’ Handbook, Dictionary and Guide.

The detent escapement came to be called a chronometer escapement, thanks to the use of the word as a designation for a precision watch containing a detent escapement. The very first person to use the word “chronometer” in reference to a watch with a chronometer escapement seems to have been none other than Arnold himself, who coined the term “pocket chronometer” in 1782. From that point forward, and for some time, “chronometer” primarily denoted (at least, in English language watch and clock-making) a precision timepiece with a detent escapement.

As Fritz von Osterhausen points out, however, in Wristwatch Chronometers, “the main characteristic of a chronometer is its precision”, and as lever watches gradually achieved very high precision, the term came to mean, by the 20th century, any very accurate watch. Osterhausen writes: “In 1925, the Swiss Association for Chronometry defined a chronometer in the following way: ‘A chronometer is a watch which has received a certification from an astronomical observatory.’” Today, almost no one but a few diehard lovers of antiquated terminology still insist that “chronometer” should only be used to refer to a watch with a detent escapement (which is a good thing for Rolex and Omega and Breitling and a lot of other brands for whom a chronometer rating is a selling point).

Origin of ‘chronometer’
Now, for many years, I have been asking other watch enthusiasts whether they know who invented the term. As the answer has generally been “no”, it has given me a chance to smugly repeat the conventional wisdom, as found in Rupert T Gould’s The Marine Chronometer: Its History and Development (and elsewhere), that it was apparently coined by an English clockmaker named Jeremy Thacker in a pamphlet on the longitude problem that was published in 1714. The funny thing is, information gets easier to find every day and in doing research for this story, I started to run across assertions that the pamphlet was a “probable satire” and that, in fact, there may never have been a Jeremy Thacker, horologist and pioneering longitudinarian, at all.

Let us look at the evidence. In 1714, a pamphlet was published, with the author’s name given as Jeremy Thacker. Now, given the title of the pamphlet, it is interesting that the possibility of its being a satire did not occur to someone sooner. The pamphlet is called The longitudes examin’d: Beginning with a short epistle to the longitudinarians, and ending with the description of a smart, pretty machine of my own, which I am (almost) sure will do for the longitude, and procure me the twenty thousand pounds.

That kind of language already sounds like someone is pulling your leg. Here’s a little background. The first Longitude Act, establishing the £20,000 prize, had been passed earlier that year and Thacker’s pamphlet was just one of many, many reactions. As you might expect, the enormous amount of money offered for a solution to the longitude problem brought a lot of cranks out of the woodwork in very short order, and Thacker takes to task several of the more egregious examples of improbable solutions to the longitude problem in his pamphlet. He also used the word “chronometer” for almost the first time it is known to have appeared in print in English. After going to considerable length to describe his ideas for a reliable sea clock, he writes: “In a Word, I am satisfy’d that my reader begins to think that the Phonometers, Pyrometers, Selenometers, Heliometers, Barometers, and all the Meters are not worthy to be compared with my Chronometer.”

Everyone from Rupert T Gould to Dava Sobel (in her bestseller Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time, which first made the general public aware of the longitude problem) seems to have taken at face value the notion that Thacker was a real person, and that his proposal was serious. However, in a 2011 book, Documenting Eighteenth Century Satire: Pope, Swift, Gay, and Arbuthnot in Historical Context, author Pat Rogers makes the claim that Thacker was the invention of a Dr John Arbuthnot. Arbuthnot was a physician and mathematician and, most significantly, he was a member of the Scriblerus Club — a group of satirists that included Alexander Pope and Jonathan Swift.

I will not go into all the details in depth, but Rogers has done some pretty impressive research in support of the idea. First of all, Jeremy Thacker is absent from any of the records of the time: There is no record of his birth, nor of his having been professionally active; no marriage, children or obituary. No other written works or correspondence of his exists. (Other authors referring to his pamphlet in later decades and centuries variously described him as a clockmaker, amateur instrument maker, amateur scientist-mathematician and so on, but there are no sources to support any of that.)

Second, Swift and other Scriblerus members are on record as having referred to the prize-motivated attempts to win the Longitude Prize as largely absurd, and a ripe subject for satire — Swift once wrote to his friend Esther Johnson, “Do you know what the Longitude is? A Projector (an archaic usage, meaning someone who sets up and plans a project) has applied to me, to recommend him to the Ministry, because he pretends to have found out the Longitude. I believe He has no more found it out than he has found out mine arse.”

Swift and Arbuthnot were close friends — Swift, generally happier than not to satirise anything on two legs, is supposed to have said of Arbuthnot that the only fault an enemy could lay upon him was a slight waddle in his walk. More relevantly, though, Arbuthnot’s amiability extended to his being notoriously disinterested in getting credit for his own work and ideas, which lends additional credibility to the idea that he might have been behind the elusive Jeremy Thacker.

The lack of any evidence of Thacker’s existence, as well as the grandiose tone of the pamphlet and its unashamed announcement of the hope of financial gain as Thacker’s main motivation, are interesting indications that Rogers may be right, and that the author’s intention was satirical. (The pamphlet is also included in an anthology of Arbuthnot’s work published shortly after his death, although that source — The Life and Works of Dr John Arbuthnot, MD, MRCS — is not considered totally reliable.) Still, the question remains open, and absent something such as a birth or death record, we will probably never know for sure.

The other interesting note to all this, however, is that despite Thacker’s coinage of “chronometer” being generally taken as gospel, it is not actually the first known occurrence of the word in English.

As it turns out, the earliest the word shows up in print is the year before Thacker’s pamphlet — in 1713, in a book by the theologian and philosopher William Derham. Derham was a clergyman, a prolific writer, a very active scientist, a naturalist and, as it turns out, a clockmaker. One of his works is The Artificial Clock-maker, a technical text on the subject. He was familiar with the work of the mathematician, physicist and horologist Christiaan Huygens (the inventor of the first accurate pendulum clock) and translated some of his works.

In 1713, he published his Physico-theology, Or, A Demonstration of the Being and Attributes of God from His Works of Creation, which is a look at the world and its inhabitants — human and animal — from a naturalist’s perspective. In it, he argues that every feature of the natural world is evidence for the existence of a Creator. The footnotes in the book are extremely detailed — longer than the text proper, in many cases. (His notes on his experiments on animals are kind of hair-raising: He seems to have spent a lot of time putting the Earth’s wee creatures in his vacuum chamber and seeing how long it took for them to expire. His asphyxiations of a mole and a bat are described with clinical detachment, and make for exquisitely depressing reading.)

However, in the chapter on light and optics, we find this passage: “But according to my own Observations made with one of her Majesty’s Sakers (a medium cannon in use at the time) and a very accurate Pendulum-Chronometer, a Bullet, at its first discharge, flies 510 yards in five half Seconds, which is a mile in a little above 17 half-seconds.

So, there it is — the earliest use I can find anywhere of “chronometer” in the English language. I think it is fair to say, though, that the term probably originated earlier than Derham’s book. He uses it as if it is already a well-known scientific and horological term of art, and for any educated person of the era, it would have been a natural coinage — the word is derived from ancient Greek roots and means “to measure time”. It may not be that much older than 1713 — there would have been no need for it before precision timekeepers needed to be distinguished from less precise ones, and Huygens’ first pendulum clock dates to 1657.

Greek roots
But you never know. The ancient Greeks had the word “chronograph”, although the term meant the keeping of historical records. The ancient Greek for a time-measuring instrument is “chronolabon”, literally something that “takes” the time. This word shows up around AD400 (in the writings of Proclus of Constantinople, if you are curious), so it is perfectly possible that “chronometer” in the sense of a time-measuring instrument, is a lot older than we can discover for now. In modern Greek, “chronometro” can mean either a timer specifically, like a stopwatch, or a chronometer in the sense of a precision timekeeper, but the word seems not to have occurred in classical literature.

Despite Swift and the other Scriblerus members’ conviction that methods for finding longitude were about as intellectually respectable as proposals for perpetual motion machines, John Harrison was able to demonstrate a practical sea chronometer only a relatively short time after the 1714 Longitude Act. As a young man, Harrison had finished his first clock in 1713, and by 1761, his marine timekeeper H4 had made its proof-of-concept voyage to Jamaica, enabling the HMS Deptford to find its longitude with an error of only one nautical mile. And by then, of course, the escapement, which would come to be synonymous with the word “chronometer”, had already been invented by LeRoy.

It is kind of fascinating to think, though, that the two earliest known uses of the word came from such different contexts. One was a serious text on the evidence for a divine hand in the structure of the universe. But the other, almost-first use of a word that became synonymous with precision timekeeping, and which represents a major marketing point for every brand that uses it today, was in what may have been a satire. — Bloomberg LP

Originally published by Jack Forster on hodinkee.com

This article appeared in Issue 790 (July 31) of The Edge Singapore.