Wristwatch

(CC) Photo: Jakub Sivek
A wristwatch made by Swiss watchmaker Tissot.

A wristwatch is a timepiece designed to be worn around the wrist, held on by a band. Modern wristwatches are often referred to simply as "watches", and are mostly electronic, despite having either an analog or digital appearance. There are wristwatches that are still entirely mechanical but because of the higher manufacturing and maintenance cost, these are becoming more rare and are considered "luxury items" or "antiques".

Brief history of timekeeping

At some point in civilization (approximately 5000-6000 years ago), it became important for Middle Easterners and Northern Africans to start managing time more efficiently.

The reasons for wanting to keep time, though, are speculative at best; but it should be noted that even early man may have done things during times of daylight and night. Hunting game, for example, was probably best done during the hours of which man could see and track his prey.

The earliest device for dividing time into units was possibly created by the Egyptians around 3500 BC (although the Sumerians may have had similar structures). It was the obelisk, and allowed observable change in units throughout the day from a moving shadow that indicated the change in position of the sun. A similar device, the shadow clock, came into existence around 1500 BC and was divided into real, measureable units to determine time of day. The shadow clock divided the day into ten sections with two sections for parts where the sun was either setting or rising. At the midpoint of the day, the device was rotated(in this sense signifying an early way of dividing up AM and PM).

Meanwhile in other places around the world, different mechanisms were used to keep time although most were based on units of water flow over time. The greek word clepsydras ("water thieves") was used around 325 BC to describe stone vessels that were shaped in such a way so that water could flow out in a rate that would fill another vessel that was marked. The big difference was that these clepsydras did not rely on celestial positionings. Their primary disadvantage was accuracy: water is subject to the environment around it, and was extremely difficult to measure in accurate quantities.

Evolution of mechcanical time

In the early 14th century, large mechanical clocks were invented and used in cities in Italy. They were driven by weights, and were regulated by a verge-and-foliot escapement. This method of regulating time was implemented over 300 years, until the invention of spring-powered clocks by Peter Henlein somewhere between 1500 and 1510 in Nuremburg. This was the first key component allowing better, portable clocks. Henlein was also the man to create the first watch. His occupation as a locksmith made him also a mechanic and a toolsmith and this gave him experience in crafting smaller, operational mechanisms.

Henlein, unfortunately did not create the most accurate watch design. With timepieces now becoming portable and carryable, the forces of motion generated by the movement of the timepiece had detremental effects on the mechanisms inside. From Hen lein's time onward, the focus became on developing a better, more efficient watch that kept accurate time. The first stabilizing mechanism invented was called the stackfreed, but it was unrefined and inefficient, giving way to the fusee.

A Swiss mechanic living in Prague by the name of Jacob Zech developed a solution to one of the problems of innaccurate timekeeping around 1525. It was his work on the fusee, and that of another Swiss by the name of Gruet whom perfected it. At this point in history Swiss timepieces became the most sought-after because of their increased accuracy.

In 1550 and 1600, screws, brass wheels, and crystals began to appear in timepiece construction. It is suggested that Edward the VI was the first Englishman to possess a watch. For many years around this point in history, watches were something of a commodity; royalty wore them especially decorated and adorned and for most citizens it became a custom to carry one.

The next real mechcanical advancement came in around 1665, seemingly by two seperate inventors looking for a way to replace pendulums within a clock (pendulums were used because of a property known as isochronism that they exhibit). An Englishman by the name of Hooke, and a Hollander by the name of Huyghens both developed the concept of a hair-spring, which exhibit approximately the same isochronism as a pendulum.

In 1704, another Swiss by the name of Nicholas Facio further enhanced watch accuracy by the introduction of bearings made from jewels. The advantages of using very small gemstomes as watch bearings are that they exhibit almost no friction in movement, and are very hard and smooth. The value added by the presence of these tiny gems is practically negligable.

Because much of the world was still being discovered and trade between nations by sailing ship had been established, a new application for even greater accuracy in timekeeping became necessary: navigation. Many governments of Europe offered rich rewards for a timepiece that could assist with the exact determination of longitutde and latitude at sea. In 1764, an inventor named John Harrison came up with the gridiron pendulum, and was put to a navigational test. On a voyage to the West Indies, his timepiece managed to only vary by a minute and four seconds during a five-month span.

Other minor additions would come to the modern watch: during the American Revolution, Thomas Mudge developed the modern escapement; soon after a Swiss-Parisian Abraham Louis Breguet made an improvement to the hair-spring, and by 1800 the fusee had been done away with all together, reducing the bulk and size requirement for the mechanisms inside.

The Electronic Time Age

The first battery-operated electric watch was developed by the Hamilton Watch Company between 1946 and 1957. The "Hamilton Electric 500" was announced at a press conference as the "watch of the future". However, the development of it was not complete by the time the company decided to announce it's invention and suffered from major design problems: a short battery life, and a flawed design which was susceptible to utter electronic failure. The production of the 500 ended in 1969.

Despite being extremely unreliable, the watch was a greater inspiration to a technology developed in the late 1960s: the quartz movement.

Anatomy

A wristwatch is comprised of three main pieces: a watchband, the watchface, and the crystal which protects in components inside the watchface. Most crystals are made from plexiglass, ordinary glass referred to as "mineral glass", or synthetic sapphire. Some crystals are made from a combination of sapphire and mineral glass, usually assembled in layers. Seiko, a large watchmaker, makes a type of crystal that is mineral glass covered by a layer of synthetic sapphire which it called "Sapphlex".

The three types of crystals have different costs, plexiglass being the cheapest, is the least likely to shatter but is extremely scratch-prone. Mineral glass is tempered is more likely to break but is more scratch-resistant. Synthetic sapphire, having the greatest hardness is the most expensive but is brittle, and easily shatters due to it's crystalline structure.