Eric Hintz, Lemelson Center Historian
|Colt army revolver, 1860. Catalog no. AF*209337, courtesy of the National Museum of American History.|
Shown above are four technologies from the Museum’s collections—a revolver, a sewing machine, a bicycle, and an early-model electric automobile. A quiz: What do these four very different technologies have in common?
|Weed Sewing Machine Company, “Circular and Price List,” 1873. Courtesy of Smithsonian Institution Libraries.|
Answer: all of them were made in the city of Hartford, Connecticut, around 1860 to 1905. But what really unites these very different products is the method by which they were manufactured. As the Industrial Revolution unfolded during the late 19th century, these four items were among the very first mass-produced products to appear in the United States. The precision fabrication techniques introduced and developed in Hartford drew manufacturers of all kinds of products—from guns to cars—and made the city a hotbed of innovation in the latter half of the 19th century.
|Columbia Light Roadster, 1886. Catalog no 307,217, courtesy of the National Museum of American History.|
In traditional artisanal practice, a single, highly skilled craftsman would make and assemble every part of a finished product; for example, a gunsmith would make every part of a musket, “lock, stock, and barrel.” Each of the metal assemblies—the lock, the trigger, the barrel—had to be hand-filed so that they fit together properly. Thus, each musket was unique and made to order, so production volume was low and the unit cost of each gun was high. This had certain military disadvantages. First, the slow pace of production made it difficult for the United States to maintain a steady supply of arms following the Revolutionary War and during the War of 1812. Plus, if an artisan-produced musket or revolver failed on the battlefield, the army would need a field blacksmith to repair it, since each gun was unique. Theoretically, if identical copies of a master gun design could be produced with identical, interchangeable parts, a broken lock or trigger could be repaired quickly by simply changing out the part. Thus, in the first decades of the 19th century, the Army Ordnance Board began experimenting with new manufacturing techniques at the federal armories in Springfield, Massachusetts, and Harpers Ferry, Virginia, in an attempt to achieve interchangeability. They also wrote interchangeability into the requirements for all new gun orders when they contracted with suppliers.
|Columbia electric automobile, 1904. Catalog no. 310,575, courtesy of the National Museum of American History.|
Enter Hartford native Samuel Colt. Colt’s patented revolver was an important invention, but his truly groundbreaking innovation was the perfection of a manufacturing process that enabled production of 10,000 identical copies of that revolver. Colt and his workers developed precise molds for forging the basic metal pieces, and specialized lathes, drill presses, and milling machines to grind those metal blanks into the finished components. They also used jigs and bearing points to secure the blank pieces on the cutting machines, and precise inspection gauges and calipers to ensure that the finished pieces conformed to exact specifications. These specialized machine tools—machines to make other machines—eliminated the variability introduced by hand forging and filing. Thus, by employing the division of labor, specialized machine tools, and precise quality-control standards, Colt and his engineers were among the first manufacturers to achieve interchangeable parts on a mass scale.
|Inspection gauges, used to ensure the interchangeability of the 1841 “Springfield” musket. Smithsonian negative no. 62468; courtesy of the National Museum of American History.|
Colt’s superintendent, Elisha Root, was widely regarded as the finest mechanic in New England and the success of the armory attracted skilled machinists from all over the Northeast. As Root shared his expertise with the staff, Colt’s armory became known as a “college of mechanics.” These ambitious mechanics learned how to build and operate Colt’s specialized machine tools and mastered the various aspects of his manufacturing process. As they gained in knowledge, they often left Colt to apply the techniques in other industries or to start their own firms. They quickly found that the use of specialized machine tools, jigs, and inspection gauges had general applicability in any industry that required the precision forging, stamping, and milling of metal parts. Historian Nathan Rosenberg has described this phenomenon as a process of technological convergence, in which the skills and techniques learned in a given context or industry are transferred and applied for uses in other industries which seem different on the surface, but actually present similar mechanical problems. In other words, once you understood the general techniques, forging and milling a revolver’s trigger was not so different from forging and milling a sewing machine’s bobbin; once you understood how to stamp press a bicycle’s sprocket it was relatively easy to stamp press the gears for an automobile’s transmission. Thus as Rosenberg explains, manufactured items that were “apparently unrelated from the point of view of the nature and uses of the final product” were, in fact, “very closely related (technologically convergent) on a technological basis—for example, firearms, sewing machines, and bicycles.”  Or as Samuel Colt himself explained it more simply in 1854, “there is nothing that cannot be produced by machinery.” 
|Colt machinist with a barrel-rifling machine, a specialized machine tool invented by superintendent Elisha Root, 1860s. Courtesy of Connecticut State Library.|
The ambitious mechanics who originally trained at Colt’s armory were the mechanism for transferring the tools and techniques of precision manufacturing across Hartford’s burgeoning industries. It was a tight-knit community, filled with overlapping relationships. For example, Charles Billings worked for Colt as a contract die maker and die forger and became so skilled at the technique that few of his forged parts were rejected at inspection time. While working for Colt from 1854 to 1856, he met another contractor named Christopher M. Spencer. Spencer was the ultimate mobile mechanic who worked across several sectors. After leaving Colt’s in 1856, he went to work at the Cheney Brothers silk mills in Manchester, across the Connecticut River from Hartford. At Cheney’s he invented an automatic winding machine that spun silk onto a spool; the machines were built by two former Colt employees, Francis Pratt and Amos Whitney, whose Hartford-based Pratt & Whitney became arguably the most important machine-tool firm in the Northeast. While “moonlighting” from Cheney Brothers, Spencer invented a patented breech-loading, repeating rifle that was tested personally by Abraham Lincoln and adopted widely during the Civil War. In 1869, Spencer reunited with his former colleague in Hartford to form Billings & Spencer, a firm that specialized in drop forgings.
Meanwhile, a former Colt machinist named George Fairfield left the firm to become superintendent and later president of Hartford’s Weed Sewing Machine Company. In 1878, with sewing-machine sales slumping, Fairfield agreed to a contract in which Weed would manufacture fifty “Columbia”-brand bicycles for Colonel Albert Pope. As bicycles boomed, Pope gained control of Weed in 1881, and shut it down altogether in 1890, as Columbia produced thousands of bicycles, and later, automobiles. After being dismissed as Weed’s president, Fairfield found another job just down Capitol Avenue, when he became president of the Hartford Machine Screw Company, a firm established in 1876 to commercialize Spencer’s latest invention, an automated screw-making machine.
The job mobility and rapid knowledge-transfer characteristic of technological convergence provide a general explanation for the emergence of inventive hot spots in different places and times. Like the precision metal-cutting tools in 19th-century Hartford, the silicon microprocessor emerged as a general-purpose technology that could be applied widely during the 1970s in Silicon Valley. After the region’s engineers learned to use microchips in mainframe and personal computers, they spread that knowledge across many different sectors, building integrated circuits into missile-guidance systems, handheld calculators, and all manner of consumer electronics. The Internet is yet another general-purpose technology developed in Silicon Valley that is applicable across dozens of sectors, and that has cemented the region’s reputation as today’s archetypal place of invention.
So what does a revolver have in common with a bicycle? What does iTunes have in common with your library’s web-based catalog? It’s technological convergence ….
 On the concept of technological convergence, see Nathan Rosenberg, “Technological Change in the Machine Tool Industry, 1840-1910,” Journal of Economic History 23, no. 4 (December 1963): 414-43, quotation p. 423.
 Samuel Colt, testifying before the British Parliament’s Select Committee on Small Arms, 1854, as quoted in David Hounshell, From the American System to Mass Production, 1800-1932 (Baltimore: Johns Hopkins University Press, 1984), p. 19.
From Prototype, April 2012.