Although it would be well into the 20th century before the watch industry achieved a very high level of interchangeability, the Waltham designers started the innovations that would eventually lead there. They also developed a highly organized factory-based work system to speed production and cut costs of watches. They completely redesigned the watch so that its movement could be assembled from interchangeable parts made on special machines. In the 1850s, watchmakers at the firm began to develop the world's first mass-produced watches. Bartlett,” a grade named for Patten Sargeant Bartlett, foreman of the plate and screw department until 1864. The movement bears the serial number 34,660 and “P. It is part of the firm’s output during the Civil War, a time that unexpectedly brought successful sales.

This watch, made about 1862, is among the earliest watch movements manufactured in the United States at what eventually became the Waltham Watch Company.