Pocket watch use peaked in the late 19th century as a wave of investment went into pocket watch design and manufacture by companies such as Elgin, Waltham, Hamilton, and Illinois. The was because railroads needed highly accurate, precision timepieces so their locomotive engineers could maintain strict schedules, thus avoiding collisions.
Hunting case watches, popular during the 19th century, have a closed cover that flips open when you push a button. By 1900, the open face watch took over and hunting case watches became less commonplace.
The shafts on the wheels of pocket watches are made of steel, and the plates are made of different kinds of brass, most commonly nickel brass (also known as nickel plate). The gears are usually made of brass, but some were made of steel and gold was used on high-grade watches.
Antique pocket watch collectors care both about a watch's movement and its case. Cases were made of different metals like silver and gold. Many were gold-filled, with two thin sheets of gold on the outside around a thicker layer of brass.
Pocket watch cases were also made from a wide variety of silver colored material, with names like silveride, usually nickel based. While gold watch cases are appealing to collectors, today's value has more to do with what was appropriate to the watch at the time.
The quality of an antique pocket watch movement is related to the number of jewels it has and other factors. For a more detailed discussion of jewels see railroad pocket watches.