Pocket watch

Pocket watches generally have an attached chain to allow them to be secured to a waistcoat, lapel, or belt loop, and to prevent them from being dropped.

Watches were also mounted on a short leather strap or fob, when a long chain would have been cumbersome or likely to catch on things.

Chains were frequently decorated with a silver or enamel pendant, often carrying the arms of some club or society, which by association also became known as a fob.

Also common are fasteners designed to be put through a buttonhole and worn in a jacket or waistcoat, this sort being frequently associated with and named after train conductors.

Watch fobs began to be used, the name originating from the German word fuppe, a small pocket.

[5] The watch was wound and also set by opening the back and fitting a key to a square arbor, and turning it.

This type of escapement involved a high degree of friction and did not include any kind of jewelling to protect the contacting surfaces from wear.

The first widely used improvement was the cylinder escapement, developed by the Abbé de Hautefeuille early in the 18th century and applied by the English maker George Graham.

Then, towards the end of the 18th century, the lever escapement (invented by Thomas Mudge in 1755) was put into limited production by a handful of makers including Josiah Emery (a Swiss based in London) and Abraham-Louis Breguet.

This development drove the Swiss out of their dominating position at the cheaper end of the market, compelling them to raise the quality of their products and establish themselves as the leaders in precision and accuracy instead.

[8] A famous train wreck on the Lake Shore and Michigan Southern Railway in Kipton, Ohio, on April 19, 1891, occurred because one of the engineers' watches had stopped for four minutes.

These standards read, in part: ...open faced, size 16 or 18, have a minimum of 17 jewels, adjusted to at least five positions, keep time accurately to within 30 seconds a week, adjusted to temps of 34 °F (1 °C) to 100 °F (38 °C), have a double roller, steel escape wheel, lever set, regulator, winding stem at 12 o'clock, and have bold black Arabic numerals on a white dial, with black hands.There are two main styles of pocket watch, the hunter-case pocket watch and the open-face pocket watch.

A hunter-case pocket watch is a case with a spring-hinged circular metal lid or cover, that closes over the watch-dial and crystal, protecting them from dust, scratches and other damage or debris.

An intermediate type, known as the demi-hunter (or half-hunter), is a case style in which the outer lid has a glass panel or hole in the centre giving a view of the hands.

As the spring unwinds and its torque decreases, the chain winds back onto the mainspring barrel and pulls on an increasingly larger diameter portion of the fusee.

This provides a more uniform amount of torque on the watch train, and thus results in more consistent balance amplitude and better isochronism.

Stem-wind, stem-set movements are the most common type of watch-movement found in both vintage and modern pocket watches.

Fusee chain-driven timing was replaced with a mainspring of better quality spring steel (commonly known as the "going barrel") allowing for a more even release of power to the escape mechanism.

The problem was completely solved through the use of special alloys for the balance and hairspring which were essentially immune to thermal expansion.

Isochronism was occasionally improved through the use of a stopworks, a system designed to only allow the mainspring to operate within its center (most consistent) range.

The most common method of achieving isochronism is through the use of the Breguet overcoil, which places part of the outermost turn of the hairspring in a different plane from the rest of the spring.

The gradual overcoil is obtained by imposing two gradual twists to the hairspring, forming the rise to the second plane over half the circumference; and the Z-bend does this by imposing two kinks of complementary 45 degree angles, accomplishing a rise to the second plane in about three spring section heights.

Due to the difficulty with forming an overcoil, modern watches often use a slightly less effective "dogleg", which uses a series of sharp bends (in plane) to place part of the outermost coil out of the way of the rest of the spring.

Until early in the 20th century, though, the pocket watch remained predominant for men, with the wristwatch considered feminine and unmanly.

As vests have long since fallen out of fashion (in the US) as part of formal business wear, the only available location for carrying a watch is in a trouser pocket.

In some countries, namely the US, a gift of a gold-cased pocket watch is traditionally awarded to an employee upon their retirement.