The Dawn of Innovation (24 page)

To his lifelong regret, Hall caved. In the final arrangement Hall retained manufacturing rights but agreed to share licensing income. In retaliation against Thornton, however, Hall vetoed all licensing deals, which crippled the marketing of the weapon. Thornton thereafter became his nemesis, as Monroe had warned.

The central problem for breechloaders was the gas seal, and the military had great interest in any weapon that could solve it. The rear of the barrel of a muzzle-loader is tightly closed with a threaded breech-plug, so all the explosive power is focused on the projectile. Breechloaders necessarily have a working opening in the rear of the barrel. Unless it is closed quite tightly, muzzle velocity is compromised, and the shooter can be severely injured. The problem was finally solved only when the primer, powder, and bullet were prepacked in self-contained metal cartridges.

Hall's solution placed a chamber in the breech end of the barrel held in place by lugs and a spring lock. When the lock was released, the chamber tilted up above the stock to receive the standard powder-and-ball charge. The rifleman pushed the charge into place with his thumb and then snapped the chamber back into the locked position. During firing, the positioning of the closed chamber had to be exact and tight. Hall managed that well enough to make a barely adequate gas seal. Charles Fitch considered Hall rifles from 1824 not “fine” by 1880s standards, although a great achievement for the day. “The joint of the breech-block [the chamber] was so fitted that a sheet of paper would slide loosely in the joint, but two sheets would stick.” An 1837 test at West Point showed that the rifles' muzzle velocity was about three-quarters of that of a comparable muzzle-loaded rifle, and their penetrating power only about as third as high.
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Bomford liked the weapons and arranged a small trial in 1816 that gave them high marks, but with the war over, interest waned. Hall then upped
the ante with his promise of achieving interchangeability with precision machining, which was sure to get Ordnance's attention. In the meantime, his wife's family had convinced John Calhoun, the new secretary of war, to arrange more comprehensive tests. Two separate trials and a rigorous military board review in 1818–1819 ringingly confirmed Hall's claims. The rifles proved as accurate and powerful as the standard rifle, and even more durable.
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Both rifle types scored much higher than any musket, but in ease of loading, Hall's rifle had a two-to-one advantage over the standard rifle and three-to-two over the musket. The board rated the ease of loading “
of infinite consequence in the rifle
, the difficulty of loading this arm being the great objection to its more general introduction.”
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The result was an R&D contract, somewhat like Blanchard's. Finalized in 1819, it would have answered Hall's fondest prayers, but for a near fatal catch-22 that plagued the rest of his days. He was awarded a salaried armory position as director of a “Rifle Works” with an appropriation for equipment and a workforce and, to boot, a $1 royalty for each delivered rifle. But the contract had to be performed at Harpers Ferry rather than at Springfield. Harpers Ferry was the Southern armory, heavily politicized in part because of its proximity to Washington, financially corrupt, and never as technically aggressive as Springfield. The Harpers Ferry superintendents predictably undermined him at every turn—skimming his appropriations, shortchanging him on equipment and space, filing endless complaints about the wastefulness and ineffectiveness of his methods—while Hall slowly and steadily made genuinely important advances in the mass production of precision-metal parts. He later conceded that his own naïve underestimate of the challenge lent credibility to his critics: “I was not aware of the great length of time that would be consumed . . . to effect the construction of the arms with the perfect similarity of all their component parts.... I had been told it had been pronounced impossible by the
French Commissioners . . . and I know that all attempts to effect it in Great Britain and this Country had failed; but from an unswerving reliance on my own abilities I expected to accomplish it in a
short
period.”
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The precise extent of Hall's achievements will never be known, for all of his patent drawings and all of his machinery have been lost. His contributions to the art of specification and inspection, however, are indisputable. Accurate mass production required much more than better machines. It was essential first to define the target product with great precision. Once an ideal model had been constructed, all subsequent specifications should be taken only with reference to that ideal. Hall insisted on special purpose machines for each part and also special purpose machines to make the production machines. Placing and fixing a part in a machine required the same attention as the precision of the machine itself; it was essential, for instance, that every operation on a part be controlled from a fixed bearing point.
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In his drive for exactness, Hall also made substantial contributions to the technology of gauging. Nineteenth-century gauging consisted of molds, or receivers (a good part should fit snugly into the gauge); groove and hole gauging (the gauge fits snugly into the part); thread gauging; and limit, or go/no-go gauging, like barrel diameter plugs (plug 1 must fit, and plug 2 must
not
fit). Under Lee, Springfield was an early leader in gauging systems, but it was still not until 1821 that the armory began to insist on exactitude in barrel bore diameter, outside muzzle diameter, inside diameter of the bayonet socket, and the form, dimensions, and screw-hole placement of the lock plate. And even then, it took another two years to manufacture sufficiently accurate gauging to enforce the rules. By about 1823, Lee had a set of eleven gauges that should have allowed reasonable
control—although he was apparently not yet attempting to enforce uniformity on lock plates.
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Hall carried gauging much further. Precision gauges were constructed for every measurement: there were reportedly some sixty-three separate gauges for the rifle, leaving nothing to a workman's judgment. Hall's gauges were always made in three sets, one for workmen, one for inspectors, and a master set in the plant manager's office to monitor wear on the other two.

Hall's influence can be seen in the tenfold increase in the number of Springfield gauges between 1815 and 1845. French influences were involved as well, for Springfield had multiple French contacts, but Lee and Bomford were well aware of Hall's work, and senior artisans rotated through Springfield, Harpers Ferry, and private contractors like North. Hall's final fillip was inspections of inspections, to ferret out any nonconforming part. Hall may also have been unique among the military arms designers of the day in making machinability a consideration in his weapon's design. Better design could have greatly simplified the machining of the Charleville, for instance.

It is generally accepted that Hall made substantial contributions to forging, milling, and cutting machinery, although the details are mostly missing. He greatly expanded the application of drop-hammer die forging—shaping hot or cold metal in a steel mold with blows from a mechanized hammer—which wasted much less metal than rough-forging and grinding, and he worked on techniques to retain the dimensions of the forged shape during cooling. Most notably, Hall created a wide range of cutting machines, including a profiler milling machine
^ap
in which the work table was moved in conformity with a profile, similarly to the way Blanchard's gun stocking machine operated.

 

A.
Hall invented one of the very first breechloading rifles that had acceptable performance, although its reception was limited by its indifferent gas seal, and maintenance problems associated with rust and powder fouling in the loading breech block.
B.
Far more important were Hall's mechanical contributions in die forging, milling, and in principles of machine construction and management. Hall also pushed gauging practice to new levels of precision and rigor. Note that the gauge in the bottom drawing includes more than a dozen gauging fixtures, each addressing a particular part.

Almost all of Hall's machines were self-acting: after the workpiece was loaded and the power train engaged, the machine moved the tool or workpiece until the operation was complete. Semiskilled young men could often run several such machines at a time under the direction of a “Principal.” Hall also lavished attention on dampening vibration and chatter in his machines: they were typically much heavier than standard machines, with bases of iron rather than wood, redesigned drives and spindles, wider belts to improve trueness, and gauging to track drift from accuracy. James H. Burton, a former master armorer at Harpers Ferry, said that the Hall works housed “not an occasional machine, but a plant of milling machinery by which the system and economy of manufactures was materially altered.”
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It was not until 1824, about five years from his starting at Harpers Ferry, that Hall could finally invite Calhoun and Bomford to examine a production run of rifles manufactured on his principles. They could see for themselves “the manner in which the several parts, promiscuously taken, came together, fitted and adapted to each other.” But Congressional complaints driven by the carping at Harpers Ferry forced Bomford to suspend all production activities pending a full field trial of the rifles and an external review of Hall's manufacturing methods.
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Two more years were consumed convening the review boards and completing the investigations, but the final reports were stunning vindications of Hall. After a five-month field trial, the military board expressed “its perfect conviction of the superiority of this Arm over every other kind of Small Arm now in use,” and supplied a statistical analysis of its great advantages in speed of firing, accuracy, and durability.

The manufacturing review was even more glowing. Hall's system was adjudged to be “entirely novel” with “the most benefitial results to the country.” The inspectors, who were all experienced, had never before seen arms “made so exactly similar to each other . . . [that] parts, on being changed, would suit equally well when applied to every other arm.” They conducted an experiment of freely intermixing parts from two hundred rifles drawn from different annual production runs and found that “we
were unable to discover any inaccuracy in any of their parts.” The reviewers also made particular note of Hall's poor working conditions and hoped that he might “receive that patronage from the Government that his talents, science, and mechanical ingenuity deserve.”
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The board's hopes were in vain, and the sniping from Congress and Harpers Ferry continued, but the report saved Hall's contract. The first substantial order for Hall rifles, in 1828, came from state militias, which the armories by law could not supply, so Bomford directed it to Simeon North, although he deputed Hall as his inspector. To Hall's great frustration, Bomford sent North one of the Hall rifles as a pattern—so even Bomford had missed the point that a “pattern” is a rigorously created and maintained ideal, not just a sample unit pulled from the production line.

The relationship with North got off to a rocky start when Hall arrived at Middletown with his full panoply of gauges and pronounced North's output unacceptable. But North, of all gunsmiths, could understand what Hall was about, and as he came to appreciate Hall's achievement, reproduced the system in his own factory—interestingly, with different machines and different gauges. It took another several years, but by 1834, Hall and North had fully demonstrated to the War Department that parts from both Middletown and Harper's Ferry could be “promiscuously” intermixed and readily reassembled into perfectly functional rifles.

Modern comparisons of Hall rifles confirm that the breech parts, which were the most demanding construct, were in fact interchangeable both between the North and Hall plants and between different rifle vintages. Tolerances on the breech opening among rifles in new condition were between 0.002 and 0.004 inches. In that same period, Joseph Clement was reportedly striving for 0.002 tolerances in constructing the Babbage calculating engines.
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So Hall and North were working at the very edge of the era's machining technology.

By then Hall was in his mid-fifties and increasingly ill, possibly from tuberculosis. His rifle was slowly becoming obsolete and was soon eclipsed by more modern weapons from gunsmiths like Christian Sharps—the Sharps rifle may have been the favorite of Union troops—and B. Tyler
Henry, whose Henry rifle was a prototype for the long-running Winchester. Hall quietly continued on salary at Harpers Ferry, tinkering with his system until his death in 1841. His place in the story gradually faded into a mere footnote. As one popular history written in the 1950s put it, “by 1820, Hall, using Whitney's techniques of interchangeable manufacture, was turning out his rifles at Harpers Ferry.”
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