In 1850, at Roxbury, Massachusetts, David Davis, Edward Howard, and Aaron Lufkin Dennison formed the company that would later become the Waltham Watch Company. Their revolutionary business plan was to manufacture the movement parts of watches so precisely that they would become fully interchangeable. Based upon the experience of earlier failed trials, Howard and Dennison eventually perfected and patented their precision watch making machines, creating what has been called the American System of Watch Manufacturing.
The original name of the company, which began operations in 1851, is unclear. Some sources say the name was the "American Horologe Company". However, in 1886, Dennison stated that the first company name was the Warren Manufacturing Company, named for General Warren of Roxbury, a famous soldier of the War of Independence. The word "watch" was specifically omitted to retain secrecy of the novel operation.
In 1851, production began in a new factory building. In late 1852, the first watches were complete. The first 17 watches, which ran for 8 days, and were marked "Howard, Davis & Dennison", were distributed among company officials. Number 1, given to Howard, is now at the Smithsonian Institution. Numbers 18 to 100 were named "Warren, Boston" and the following 800 "Samuel Curtis", after the financial backer of the company. A few, marked "Fellows & Schell", sold for $40. January 1853 saw the introduction of the "P.S. Bartlett" watch, named for early employee Patten Sargeant Bartlett.
In September 1853 the company was renamed the Boston Watch Company. A new factory was built in Waltham, Massachusetts, on the banks of the Charles River, which the company occupied in 1854. Growth of the company prompted significant expansion of these premises, whose surviving elements now date to the period 1879–1913. Now repurposed to residential and commercial use, the complex was listed on the National Register of Historic Places in 1989.
The next movements manufactured (1001-5000) were marked "Dennison, Howard, & Davis", "P.S.Bartlett", and "C.T. Parker". The company had financial difficulties and Howard left to form E. Howard & Co.