Midnight Ride, Industrial Dawn

by Robert Martello

  Revere’s decision to enter the bell-casting field also marks a turning point in his perception of his career. While he enjoyed the status of a skilled craftsman before the war, in the years that followed he hoped to use technical work as a springboard to a position of societal service, at which point his sons could take over the workshop. By 1792, his merchant career had clearly failed to take off, and while there is no reason to believe that Revere lived an unhappy life or disliked his silver and iron trades, he also must have understood that he had not moved any closer to the upper classes. Bell making started out as a chance to help his church out of a bind while adding a lucrative new product to his repertoire, but this new activity soon reinforced an important lesson: manufacturing had its own rewards. Revere now had the opportunity to craft beautiful items that proclaimed the glory of God while also serving practical societal needs. Bells also made a statement about America’s growing manufacturing competence, all the more powerful due to the absence of local bell casters. Revere could serve his religion, his society, and his bank account at the same time. This advanced high-profile technical work unknowingly started a pattern that defined the remainder of his career. Over the next few years he produced cannon, bolts, and spikes for his government, and in so doing helped it to overcome the great technological gap separating it from potentially hostile foreign powers. Throughout the 1790s the practical and symbolic importance of technology became increasingly clear to Revere, his community, and the American government. Beginning with that first bell, he realized that the makers of quality items played their own vital role in the history of the new nation.

  Becoming a Bell Maker: An Art and a Science

  Early metalworkers undoubtedly noticed the sound-making potential of different alloys whenever they banged a newly made bar or sheet and observed its vibrating tone. The earliest bells, intentionally produced for that purpose, probably appeared in China, as they are mentioned in various myths and legends there dating to the twenty-ninth century BC. In the Western world, Greeks on the island of Crete produced bells at points between 2000 and 1800 BC, with bronze bells in Athens dating to the sixth century BC. These early bells often carried mythic overtones, as various legends associated their peal with the ability to separate truth from falsehood or punish wrongdoing. As different societies gained metalworking experience, particularly in the field of casting, they learned to produce larger bells capable of being heard at farther distances. Christian churches started using large bells in Western Europe and England around the eighth to tenth centuries AD, becoming both prominent and prevalent by the eleventh century. Large bells encouraged architectural changes in churches, such as the development of high front gables, soon known as bell towers, which extended the range of their music even farther and summoned the most distant townspeople to services.5

  Although bells served many different purposes, the church bell played the largest role in early American society. Looking down upon the world from majestic towers at the tops of churches, often the largest structures in places like religious New England, church bells maintained the highest possible visual and auditory profiles and illustrated the symbolic power of technology. Church bells served a variety of named functions each week: for example, the “Gabriel” bell woke the community; the “Sermon” bell summoned parishioners to church services; the “Pardon” bell symbolized the pardoning of sins in the middle of some services; and the “Passing” bell announced the death of a community member with three sets of three rings for an adult male, followed by one ring for each year of his age. Bells also served as important instruments of general communication, used for fire alarms or to proclaim momentous news. Some deacons left bell ropes hanging outside their churches to allow community members to ring them in emergencies. Church bells held such an esteemed societal role that they often inspired complimentary verses, either published or inscribed on the bell itself. Many bells cast by Revere and others carried the inscription “The Living to the Church I Call, and to the Grave I Summon All.” An anonymous writer humorously outlined the connection between church bell and parish in 1816 when Revere’s largest bell made its debut in the stone tower of King’s Chapel:

  The Chapel Church

  Left in the lurch

  Must surely fall;

  For Church and people

  And bell and steeple

  Are crazy all.

  The Church still lives,

  The Priest survives,

  With mind the same.

  Revere refounds

  A bell resounds

  And all is well again.6

  The complexity of the manufacturing process grants each bell a unique personality and, one hopes, its own special allure. Metallurgists often describe bell making as both an art and a science, partly because minor variations in every aspect of the procedure enable workers to produce a nearly infinite range of final products. The quality of a bell’s sound primarily depends on factors such as the type, quality, and proportion of metals and the shape and size of the mold. Increasing the amount of copper, decreasing the percentage of tin, or adding small amounts of other metals affects each bell’s final attributes. Bell making also requires an understanding of geometry and general mathematics, to enable the bell maker to scale a general pattern to different sizes without altering the bell’s complex acoustical properties. When struck properly, bells emit a musical chord consisting of main note called the “fundamental,” a “nominal” note an octave higher, a “hum” note an octave lower, and several “partial” notes in between. The topmost parts of the bell emit the higher notes and the low hum note emerges from the lowest part, or lip, of the bell. Therefore, each alteration of the ratio of height to width, the thickness at any point, or the overall size of the bell completely changes its volume and tone. A skilled bell founder can pitch a bell in different musical keys based upon its size and dimensions, and can alter the bell’s sound during the tuning process by removing metal to diminish some of the partial notes while maintaining the proper intervals between the entire chord. The rare bell able to produce a desired sound without tuning is known as a maiden bell, the holy grail of bell founders.7

  Revere’s records illustrate the difficulty in scaling a bell mold to a different size. One 700-pound Revere bell measured 32 inches diameter across the bottom, 27 inches high, and 17 inches across the top. In comparison, the 2,437-pound bell at King’s Chapel in Boston, the largest ever cast by Revere and Son, measured 49 inches across the bottom, 36 inches high, and 27 inches across the top.8 Revere struggled to optimize his bells’ shapes and weights throughout his career, as illustrated by occasional customer complaints or severe miscalculations of some bells’ final weights.

  Bells seemed to invite paradoxes, as their sounds had to be simultaneously loud, clear, and beautiful. No two church bells sounded the same, and especially in a large town such as Boston hosting many churches, the sound of one’s bell was well known by members and nonmembers alike, representing that parish in the eyes and ears of society. Revere the artisan, maker of beautiful objects, worker of metals, and lover of all things technical, immediately and irrevocably succumbed to the enchantment of bells. He embraced the many intricacies of bell casting from 1792 through the end of his life, producing drawings, recipes, and sample bells in his drive to unravel the perfect combination of metals and the optimal bell production process, as did countless bell makers before him.

  Bell casting first introduced Paul Revere to the challenges of working with copper, by far the largest component of bell metal. Copper shares some of silver’s characteristics such as its high degree of malleability, but also offers some of the functionality of iron. Unlike Revere, early human societies worked with copper well before iron because they could more easily smelt it into a usable form. Most copper occurs in copper ores that combine metal, oxygen, and other elements in a rocky mineral. The visual distinctiveness of these ores and the existence of surface deposits in many parts of the world undoubtedly aided the early adoption of copper.
Malachite, for example, is a fairly common copper ore known for its beautiful green color. The first copper smelting took place in the Sinai desert in southern Israel, approximately around 3500 BC, perhaps as an unintentional byproduct of pottery firing. Copper smelting is a physical and chemical process requiring heat above 1084 degrees C as well as a chemically “reducing” atmosphere rich in carbon but lacking in oxygen. These conditions are hard to create accidentally, but definitely exist within a pottery kiln.9 Copper mines and artifacts have been found at various European sites dated between 4000 and 3000 BC, with a general diffusion of the technology from southern to northern Europe and west to East Asia. Common copper items of the ancient world included agricultural tools such as sickles and plows, carpentry tools, and ornaments.10

  Copper, while harder than metals such as silver, still proved fairly soft and of limited utility in items such as blades, weapons, and armor. Early smiths could harden copper through hammering and heating, but this ran the risk of making the metal brittle and unusable. Copperworking technology underwent a dramatic improvement when ancient metalworkers began experimenting with alloys, or different mixtures of metals, in search of improved physical properties. After unsuccessfully experimenting with copper-arsenic alloys, metalworkers settled on the combination of copper and tin, known as bronze.11Bronze offered many advantages over copper, such as increased hardness and strength, fewer bubbles produced during cooling, and a lower melting point (around 950 degrees C) that made it easier to work. Bronze first appeared in the Near East and Mesopotamia around 3000 BC, and caused an explosive growth in overall metal production and mining, with bronze weapons and armor quickly gaining ascendancy over their competitors. Bronze remained the preferred metal alloy for more than one thousand years and gave its name to a dynamic age of human history.12 The rise of iron, discussed in the previous chapter, eventually reduced the general demand for bronze goods because of iron’s greater strength and hardness. However, bronze continued to serve wherever one needed a lighter or more ductile substitute for iron. Because of the acoustical properties of bronze, bells became one such application.

  Bronze alloys have many intrinsic advantages for cast items such as large bells. A tough metal, bronze can withstand the shocks and impacts that bells receive throughout their lives. It also melts at a relatively low temperature, which allows the caster to ensure that it melts in a uniform manner, not hardening until all the metal has time to fill the mold. Bronze is fairly soft, especially in comparison to iron, which makes it much easier to manipulate during the tuning process. Bronze’s softness also relates to its elasticity, which allows the bell’s vibrations to last a long time and propagate over great distances. Finally, bronze resists corrosion and is lighter than iron, essential qualities for items hoisted into high towers and exposed to the elements.13

  The composition of bell metal remained a matter of great inconsistency at the time that Revere contemplated his entry into the bell-making trade. Most bells consisted of copper alloys, but the ratio and range of metals in these alloys depended on tradition e ach bell maker’s preference, and the local abundance or scarcity of each constituent. Although modern experts define bell metal as a variant of bronze consisting of 75 percent copper and 25 percent tin, many bell makers experimented with small additions of other metals to improve the bell’s sound. Some bells include quantities of zinc, which combines with copper to form brass, an alloy with similar properties to bronze. Most bell makers also added minute quantities of silver or even gold to their bells largely out of the superstition that this would produce a sweeter sound. Contemporary bell makers kept descriptions of the proportions of different metals, heating times, and temperatures purposely vague, either to guard trade secrets or to acknowledge the fact that they failed to follow one consistent recipe. One definition stated that “Bell-metal is a composition of tin and copper in due proportion; which has the property, that it is more sonorous than any of its ingredients taken apart.” A study of fragments of a Revere bell shattered by lightning illustrates that he followed the prevailing wisdom concerning bell composition: his bell consisted of approximately 77 percent copper and 21 percent tin, with small amounts of lead, arsenic, zinc, nickel, and silicon, and a trace of silver. The lesser ingredients probably resulted from impurities in the copper, although Revere probably added the silver intentionally, a hopeful nod to the prevailing tradition.14

  Bell making remained a high-tech trade in Revere’s time, and all large bells in America had to be ordered and imported from England. The first and most famous bell produced in America, the Liberty Bell, originated in England but cracked upon its first striking. Philadelphia’s Pass & Stowe foundry recast the Liberty Bell in the 1750s and needed two tries to produce one with an acceptable sound. The number of early bell makers, while undoubtedly small, is obscured by the fact that several foundries, such as Revere and Son, probably cast a small number of bells alongside their normal activities such as blast furnace operations, iron casting, and other metallurgical work.15 In this way the early American metalworkers formed a loose professional network that transcended any single material, product, or process: most skilled workers who attained mastery in some aspect of metalworking offered advice or aid to the others. Upon receiving the contract to cast a new bell for his church, Revere would have attempted to contact anyone who could offer pertinent advice, especially local experts. He almost certainly learned some of the details of bell casting from Aaron Hobart of Arlington, Massachusetts, one of the few Americans who understood the principles of bell founding in the early 1790s. But Revere’s bell-making preparations predate his 1792 contract, as revealed in earlier correspondence directed at metallurgical research.

  Revere first investigated the possibility of casting bells, at least briefly, several years earlier. Nicholas Brown wrote to him in October 1789, responding to an earlier letter in which Revere asked many questions about bell making. Brown had witnessed the bell-casting process at his furnace, although he did not qualify as an expert. Brown informed Revere that a recently cast bell cost more than 60 pounds sterling and consisted of 60 pounds of copper and 35 pounds of block tin, a deviation from current and eighteenth-century metal proportions. This letter makes repeated mention of Brown’s papers on the subject of bell making, such as “I set to overhauling the file of papers about recasting our meeting bell,” and “I found authors differed about the loss & proportion of metal,” providing another illustration of the research that all metalworkers commonly performed and the importance of any available expertise.16 Even without Revere’s original letter to Brown, it seems clear that he had toyed with the idea of bell making since 1789.

  In late 1791 Revere’s interest in metallurgy took on a heightened and more scientific intensity. He began a correspondence with Doctor Lettsom (which he misspelled “Lestrom”), a London scholar. Revere’s questions to Dr. Lettsom illustrate his advanced knowledge on many aspects of metallurgy as well as his practical curiosity concerning related topics. Before writing Dr. Lettsom, Revere tested a sample of tin from a recently discovered Massachusetts source. After describing the sample as “1/32” heavier than his sample of Cornwall block tin, Revere theorized that his ore sample was not “divested of the crude minerals which it is commonly mixed with,” possibly implying that it was what the miners call stream tin. He requested Dr. Lettsom’s opinion, as well as samples of “shade, stream, and mine tin” from Cornwall or Devon “in their crude state.” Revere sent Dr. Lettsom some samples of minerals found in the area and promised to continue doing this every spring and fall, “for I am realy selfish in the cause, for I doubt my abilities in chemistree, and am sensible that I shall git a true estimate of all that I shall send you.” Dr. Lettsom responded in August 1792, and sent Revere the tin ores he requested. He also identified Revere’s samples and mused about the establishment of a mineralogy school at Harvard. In March 1793 Dr. Lettsom responded to another letter and identified a new batch of minerals sent to him.17 This abstract research did not direc
tly relate to Revere’s work; he needed to cast the copper and tin, not learn to identify different ores. This correspondence does illustrate his interest in the field, and increased his overall understanding of metallurgical processes. In addition, the ease with which Revere obtained valuable advice, feedback, and physical samples from a well-known scholar in a different nation clarifies the early scientific and technical networks of the English-speaking world. Unlike the American politicians who refused Revere’s requests for appointed positions, Dr. Lettsom saw merit in this American stranger’s scientific questions and took the time to respond. The lack of professionalism allowed the small number of interested amateur scientific practitioners, typically self-funded gentleman-scholars, to make useful contributions such as Revere’s samples and observations. Revere must have received a bit of a thrill when a noted scientific expert and writer took the time to converse with him as an equal.