Vintage and antique pocket watches

Photograph: Antiques Roadshow

Up until the last part of the 17th century there were no truly personal, portable timepieces. However, with the development of the balance spring, or hairspring, watches that could count minutes as well as hours became feasible. Plain and sturdy English watches were the norm. Pocket watches were not even produced in the United States until 1809, and broader manufacturing did not happen until the 1850s.

Cases were designed to protect pocket watch movements, but were often very ornamental as well. Some early pocket watches had two cases, which gave more protection to the movements. These were called pair-cases watches. Enameled watch cases were produced in Switzerland and were especially popular in the late 18th century. Novelty watches became fashionable in the 19th century and brought together the art of the jeweler and the craftsmanship of the watchmaker. More affordable, and more common, were open-face watches, with no cover over the glass, made of gold or silver.

Prior to the Civil War, most watches were wound with a key. In the 1860s keyless winding became more common. From the mid-nineteenth century until the 1950s, the Chicago and Boston areas were centers for the mass production of American mass-produced watches.

Railroad watches developed as a result of a series of terrible railroad accidents. Engineers and conductors required highly accurate timepieces. At the same time, they had to be inexpensive enough for engineers and conductors. The railroad watch was the result, what has been called "an affordable triumph of accuracy." By the late 19th century railroad watches had become popular with the general public, their accuracy being a key selling point. Waltham and Elgin were among the biggest and best manufacturers.

Movement - the heart of a watch, the timekeeping mechanism. Has gears, a balance wheel and moving parts (quartz watches do not have movements.)

Jewels - Synthetic sapphires or rubies used to reduce friction in mechanical watches. They add to the accuracy and dependability of watches. Usually there are 15 or 17 jewels in a watch, but those with complications may have as many as 26.

Face or Dial - The area of a watch that displays the numbers, minutes and hour markers that tell the time.

Hands - Usually metal, they indicate the hour, minutes and seconds

Watchcase - houses and protects the movement. Watchcases can be made of gold, silver, steel, plastic, silver-plated metal, aluminum, platinum, or titanium alloys.

Crown - set on the side of a watch, a round button that is usually ribbed, used to set and wind a watch

Crystal - protective lens covering the watch face, made of clear sapphire glass, plastic, or mineral glass

Bezel - metal rim surrounding the face and holding the watch crystal

Incabloc - a mechanism in the watch that is shaped like a cloverleaf and shields the movement; works like a shock absorber

Caliber - the size of a watch movement

Numbers - watches use Arabic numerals, Roman numerals, sticks, or a combination of these. Some have no numbers at all.

Ebauches - the most basic watch movement, bought by watch manufacturers who then add their own refinements and complications

At How Stuff Works: Clocks and Watches Library you'll find good information explaining how timepieces work.

The Watch Guy web site was created by a watch collector who also repairs watches. It's full of excellent information and well worth a visit.

Clock and Watch Resources is a more extensive list of resources for those interested in timepieces.