Biltmore pocketwatch dating
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.
As a result, a verge watch could rarely achieve any high standard of accuracy.
In 1857 the American Watch Company in Waltham, Massachusetts introduced the Waltham Model 57, the first to use interchangeable parts. Most Model 57 pocket watches were in a coin silver ("one nine fine"), a 90% pure silver alloy commonly used in dollar coinage, slightly less pure than the British (92.5%) sterling silver, both of which avoided the higher purity of other types of silver to make circulating coins and other utilitarian silver objects last longer with heavy use.
Watch manufacture was becoming streamlined; the Japy family of Schaffhausen, Switzerland, led the way in this, and soon afterwards the newborn American watch industry developed much new machinery, so that by 1865 the American Watch Company (afterwards known as Waltham) could turn out more than 50,000 reliable watches each year.
An early reference to the pocket watch is in a letter in November 1462 from the Italian clockmaker Bartholomew Manfredi to the Marchese di Mantova Federico Gonzaga, where he offers him a "pocket clock" better than that belonging to the Duke of Modena.
Thereafter, pocket watch manufacture spread throughout the rest of Europe as the 16th century progressed.
Early watches only had an hour hand, the minute hand appearing in the late 17th century.
With this, a domestic watch could keep time to within a minute a day.
Lever watches became common after about 1820, and this type is still used in most mechanical watches today.
This fob could also provide a protective flap over their face and crystal.