Wilhelm Johann Diedrich Keuffel was one of the founding partners of Keuffel & Esser Company (K&E), a scientific instrument manufacturing firm founded in New York City in 1867. Best known for its popularization of the slide rule, Keuffel & Esser was the first American company to specialize in the manufacture and sale of drafting and surveying tools. By the early twentieth century, it was one of the largest manufacturers of scientific instruments in the world.
Wilhelm Johann Diedrich Keuffel (born July 19, 1838 in Walbeck, Province of Saxony, Kingdom of Prussia; died October 1, 1908 in Hoboken, NJ) was one of the founding partners of Keuffel & Esser Company (K&E), a scientific instrument manufacturing firm founded in New York City in 1867. Best known for its popularization of the slide rule, Keuffel & Esser was the first American company to specialize in the manufacture and sale of drafting and surveying tools. By the early twentieth century, it was one of the largest manufacturers of scientific instruments in the world. After Keuffel’s death in 1908, K&E remained a family owned and managed business until it was acquired by Kratos Corporation in 1981.
Wilhelm Johann Diedrich Keuffel was born on July 19, 1838, to Gottfried C.A. Keuffel and Auguste (née Walter) Keuffel in Walbeck, in the Prussian province of Saxony. He attended local schools before becoming an apprentice in a general store at the age of fifteen. In 1857, at the age of nineteen, he moved to Magdeburg and then to Hanover, working in hardware stores in both cities. After a period of work in Birmingham, England, Keuffel traveled to the United States in July 1866. He settled in Hoboken, New Jersey, just across the Hudson River from Lower Manhattan. On December 26, 1871, he married Bertha Caroline Schneeberger (born 1853) of St. Louis, Missouri. She was the eldest child of John Schneeberger, a successful shoe and boot manufacturer from Hesse-Darmstadt, and his wife Margaret Louisa, who was from Schleswig-Holstein. Together, Wilhelm and Bertha Keuffel had six children: Louise A. Keuffel Bergenau (1872-1960), William Gottfried (“Willy G.”) Keuffel (1875-1942), Martha Keuffel (1876-79), Ottilie Keuffel Busch (1880-1971), Margarethe Bertha (“Gretchen”) Keuffel Keller (1885-1974), and Hermann Keuffel (1886-87). Wilhelm Keuffel died on October 1, 1908, at his home in Hoboken at the age of seventy.
Keuffel’s partner, Hermann Esser, was born on December 30, 1845, in Elberfeld, in the Rhineland province of the Kingdom of Prussia. He emigrated to the U.S. in the fall of 1866 and settled in Hoboken. On September 30, 1869, he married Bertha Michelmann of Hanover in St. Matthew’s Lutheran Church in Hoboken; the couple had two children: Otto Esser (born 1870) and Klara Esser (born 1875). Esser retired from K&E in 1902, at which point he sold his share of the business to Keuffel. He returned to Germany that spring and died in Bad Godesberg am Rhein on April 16, 1908, at the age of sixty-two.
According to Keuffel family lore, Keuffel and Esser first met in Hanover, where both had worked for the Ravené Company, a Berlin-based iron manufacturer. Eventually, the company sent Keuffel to Birmingham, England, and then to the U.S. to sell its hardware products. After arriving in New York, however, Keuffel decided to part with the Ravené Company and go into business for himself, and he encouraged his former co-worker to immigrate and partner with him. Esser arrived within a matter of months.
When Keuffel and Esser settled in Hoboken in the late 1860s, the town was still a rural village best known for its wooded picnic grounds, the Elysian Fields. Hoboken had land available for development, but it was not a promising location for the kind of high-end, specialty retail business Keuffel and Esser envisioned, mostly because it lacked the retail and office space of New York City, but also because would-be customers would have to cross the Hudson River by ferry from Manhattan. Therefore, Keuffel and Esser chose to base their new business in Lower Manhattan, where customers, capital, and office space were easier to find. The Keuffel & Esser Company was established in New York City on July 19, 1867. The two partners rented office space downtown on the fourth floor of 79 Nassau Street for $5.50 per month ($83.60 per month in 2010) and planned to sell drafting and surveying equipment imported from Europe, mainly the German states. The business remained a partnership until February 16, 1889, when Keuffel and Esser incorporated as Keuffel & Esser Co. (K&E) in New Jersey. Keuffel served as president and Esser as treasurer, first of the partnership and then of the corporation, during the thirty-five years that they worked together.
To attract clients, Keuffel and Esser went door to door to architects’ and builders’ offices in Lower Manhattan, selling pencils and pens, rubber erasers, India ink, protractors, rulers, and compasses – anything and everything that an architect or an engineer needed to do his job. Although they imported much of their stock, the partners also did some of their own manufacturing, with Keuffel initially making some of their supplies by hand. As the business grew, the partners hired craftsmen to do the manufacturing, while they alternated between extended buying trips to Europe and stints at home to oversee sales and domestic manufacturing. Between 1877 and 1907, Keuffel and Esser filed six passport applications each for travel to Europe; Keuffel’s third child, Ottilie, was even born in Germany in 1880 during an extended business trip. In 1881, the partners assured their customers: “As one member of our firm is constantly residing in Europe, we are able to keep our stock always complete, shall have all the latest improvements and inventions relating to the articles of our business and offer [the] best facilities for importing goods to order, at the shortest notice and most reasonable price.” By 1883, Keuffel and Esser had opened a buying office in Berlin, and K&E had started manufacturing instruments in Germany as well.
In the 1860s and 1870s, as their business grew and as they began needing additional space for sales and manufacturing, Keuffel and Esser relocated several times in downtown Manhattan. In 1868, they moved from 79 Nassau Street to 71 Nassau Street, and in 1870, they moved to 116 Fulton Street. At the same time, they also rented space for manufacturing at 3 Dutch Street. By 1873, the company had moved to 111 Fulton Street and then to 119 Fulton Street, which had space for a large showroom. From 1874 to 1878, a K&E retail store occupied the entire ground floor between Fulton and Ann Streets. Located in the neighborhood just south of New York’s City Hall, this store was close to the offices of many architects, civil engineers, and construction companies.
In need of more manufacturing space, Keuffel and Esser leased a small loft building at the southwest corner of Third and Adams Streets in Hoboken in 1875 and transferred their manufacturing operations there. In 1878, the partners leased a building at 127 Fulton Street (sometimes known as 42nd Ann Street), in New York City, to serve as their general office and retail showroom. In 1880, Keuffel and Esser expanded their factory space in Hoboken, building a large, three-story structure at the northeast corner of Third and Adams Streets. In 1887, they replaced this facility with a large plant that occupied most of Third Street between Grand and Adams Streets. By this point, Keuffel & Esser had permanently divided its operations between manufacturing in Hoboken, where there was room to expand, and retail sales and general offices in New York City, where customers could be found.
In 1892-93, Keuffel and Esser built a new store at 127 Fulton Street to house the company’s primary retail salesrooms and general offices. The fireproof, eight-story Renaissance Revival-style building was designed by architects Theodore W. E. De Lemos and August W. Cordes, both of whom were German immigrants. In addition to being active in the local German-American community, the two were known for their designs for commercial and retail buildings. The building is now a New York City landmark. In 1907, K&E rebuilt its Hoboken factory and moved its management offices to Hoboken but kept its primary salesrooms at 127 Fulton Street. Although Keuffel and Esser would open retail stores and manufacturing plants in several cities and states over the next century, 300 Adams Street, Hoboken, and 127 Fulton Street, New York City, functioned as the company’s two operations centers for ninety years.
Having a base of operations in New York City gave Keuffel and Esser easy access to skilled craftsmen, many of whom were from the German states. Heavy immigration from German-speaking Europe from the 1840s to the 1880s meant that New York City had one of the largest German populations in the world, and German immigrants and their children comprised one third of New York’s population in 1875. As late as 1910, Germans were still the second largest ethnic group in New York City (after Russians), and they accounted for nearly twenty percent of the city’s 4.7 million residents. Hoboken was an extension of New York’s German-American community, and much of its growth in the mid to late nineteenth century was attributable to German immigration. Hoboken was the American base for the Hamburg-America Packet Company and the North German Lloyd Steamship Company, and German immigrants and their children comprised between 25 and 40 percent of its population in the late nineteenth and early twentieth centuries. 
German immigrants in New York City and Hoboken could be found in nearly every strata of socioeconomic life – they worked as merchants and entrepreneurs but also as unskilled laborers, longshoremen, luggage porters, and domestic servants. In New York City in the 1850s, German immigrants dominated the needle, boot and shoe, woodworking, baking, and tobacco trades, and the majority of German-American businessmen were grocers and peddlers. In the 1880s, half of New York City’s German-Americans worked in manufacturing, while approximately twenty percent were business owners, most commonly wine and liquor dealers, saloon keepers, and dry goods and clothing storekeepers; nearly twenty-five percent of the city’s German-Americans were white-collar clerical workers. In Hoboken in the 1850s, the most common occupations for German-Americans were merchant, cabinet maker, clerk, cane maker, carpenter, tailor, and barkeeper, but the city also boasted German-born portrait artists, painters of fine china, jewelers, and watchmakers. In the 1880s, German-Americans in Hoboken continued to predominate in the skilled trades, and to work as merchants, clerks, and retail store owners. Thus, entrepreneurs like Keuffel and Esser could easily find men trained in fine metal, wood, and glass work on either side of the Hudson, and the frequent ferry service made commuting easy for workers, who were already accustomed to traveling between New York City and New Jersey.
In 1867, when Keuffel and Esser started their business, the American drafting and surveying industries were expanding dramatically to meet the demands of a rapidly growing and industrializing nation. Nonetheless, architects, civil and mechanical engineers, and draftsmen still tended to learn “on the job” through apprenticeships, and they frequently cobbled their equipment together from hardware and stationery stores and also made some of their tools themselves.
In the mid to late nineteenth century, architecture and engineering started to emerge as professions. In the United States, the American Institute of Architects was founded in 1857, and the Massachusetts Institute of Technology began offering the nation’s first university program in architecture in 1865. Associations related to the profession formed in relatively short order; they included: the American Society of Civil Engineers (1852), the American Institute of Mining Engineers (1871), the American Society of Mechanical Engineers (1880), and the American Institute of Electrical Engineers (1884). Aside from Rensselaer Polytechnic Institute in New York, which had opened back in 1825, most American engineering programs were established in the 1870s to 1890s and were modeled after European institutions. The Stevens Institute of Technology in Hoboken, an institution with which the Keuffel family had a long-standing relationship, opened its doors in 1870. Although most architects and engineers in the U.S. were Anglo-Americans, the profession included a number of prominent German immigrants – such as De Lemos and Cordes, and John A. Roebling, the designer of the Brooklyn Bridge – and many of these men were based in New York. An early and important customer of K&E was the New York Bridge Company, which built the Brooklyn Bridge.
By the turn of the twentieth century, Keuffel and Esser had influenced the building and construction industries and the architecture and engineering professions in several ways: by introducing new tools, such as the slide rule, to the United States from Europe; by improving the design of existing tools and inventing new ones; and by helping budding architects, engineers, surveyors, and builders learn to use these new tools by selling to universities. Keuffel and Esser also helped advance the instrument manufacturing industry in the U.S. by pioneering new sales techniques and proving that a market did indeed exist for domestically-manufactured measuring tools.
Neither Keuffel nor Esser had trained in architecture or engineering, but their work in the hardware supply industry in Germany had given them a good understanding of the needs of the profession. After immigrating to the U.S., they saw that no one business specialized in architectural and engineering equipment, which meant that members of the profession had to shop at multiple stores, an often frustrating and always time-consuming task.
Keuffel and Esser’s first important innovation was specializing in the sale and manufacture of measuring instruments. By offering everything that a would-be customer needed under one roof (and then by mail order catalog, as well), K&E quickly became the store for drafting and surveying supplies in New York City and then in the whole United States. K&E’s “one-stop shopping” appealed to efficiency-minded architects, builders, and engineers who subscribed to the American capitalist mantra, “time is money.” Keuffel and Esser also allowed their customers to try out tools at their Fulton Street showroom, a very important option for any architect or engineer who was buying expensive equipment. At the same time that K&E was developing its specialization model, the department store, as a retail institution, was emerging from the dry goods business in the U.S. Although Keuffel & Esser and department stores such as Macy’s sold different products in different ways, both shared a business model that was based on envisioning a customer’s needs and trying to meet them, as opposed to requiring the customer to adapt to the convenience of the business owner.
By the early twentieth century, K&E had become one of the largest manufacturers of precision scientific instruments in the world. While the company surely benefitted from good timing, its success was primarily attributable to its innovative sales and marketing techniques, and its reputation for high-quality products. The company gradually developed products that fell into two broad categories: expensive one-time purchase items, such as surveying equipment and slide rules, and less-expensive repeat purchase items, such as pencils, ink, and paper of various sorts.
Initially, Keuffel & Esser sold drafting equipment, especially pencils, rulers, protractors, and compasses. Hermann Esser even published a book, “Draughtsman's Alphabets, A Series of Plain and Ornamental Alphabets Designed Especially for Engineers, Architects, Draughtsmen, Engravers, Painters, Etc.,” in 1869. Some of the first patents filed by Keuffel and Esser in the 1870s were for improvements to draftsmen’s tools.
In the early 1870s, K&E began selling surveying equipment, focusing on compasses, transits, levels, and theodolites. The company also started selling continuous steel tape, which was an improvement on the Gunter’s chain used by surveyors to measure distances. As with its drafting products, K&E made its own surveying tools but also sold those made by others. By the 1890s, K&E’s surveying equipment was so well regarded that it was used by Robert E. Peary and his team on their Arctic explorations.
Keuffel and Esser had been in business for thirteen years when they began selling the item that became most firmly associated with their company, the slide rule. The slide rule had been invented by English mathematician William Oughtred (1575-1660) in the mid seventeenth century on the basis of innovations by John Napier (the inventor of logarithms) and Edmund Gunter (the creator of logarithmic scales). The rule is a mechanical analog computing tool used to do multiplication, division, roots, logarithms, and trigonometry calculations. A rule can be either linear or circular – most engineers learned to use the linear type, but circular slide rules were more common in aviation (and are still used in that industry today). Before the invention of the pocket calculator in the early 1970s, the slide rule was the most useful tool for doing large numerical calculations. Despite their acknowledged utility, these devices were rarely seen in the U.S. before the 1880s.
The story of how K&E came to sell its most famous product became part of company lore, but it also said something about the two partners’ personalities and how they envisioned a market for their products.
Hermann Esser, who was prone to see gloomy possibilities where his partner was all cheer and ebullience, often found his patience sorely tried. He would never forget the day the slide rules arrived….
“After the first factory was safely launched in 1880, William Keuffel made a trip to Europe to select instruments and materials from manufacturers in Switzerland, Germany, and England. Hermann Esser remained at home to guide the firm’s growing activities. The first shipments of William Keuffel’s selections began to arrive at 127 Fulton Street in New York – fine drawing tools, precisely divided protractors and measuring scales, brushes, pens, special draftsmen’s pencils. One shipment gave Herman Esser an unpleasant surprise. It contained, to all appearances, a set of engineers’ scales, or “rulers,” but they were like none ever seen before in the K&E showroom. The central section of each rule slid back and forth between the two outer sections. What good was that arrangement for laying off lengths on a drawing? Even worse, the graduations were not equal. This was too much. His partner had completely lost his judgment!
With this first shipment, Keuffel and Esser began selling imported slide rules based on an 1859 design by French artillery officer Amédée Mannheim. The first K&E slide rules were made of boxwood and cost $3.50 ($77.00 in 2010). K&E also began marketing and then manufacturing cylindrical calculators with extra-long logarithmic scales based on an 1881 design by New York civil engineer Edwin Thacher, who sold or assigned his patent rights to Keuffel & Esser. After instrument designer William Cox invented the duplex slide rule (which placed scales on both faces of the rule and had a dual indicator with a glass-enclosed hairline on each face, thus allowing for all of the scales to be used together) in 1891, K&E patented the Cox improvements. For a period in the 1890s, Dennert & Pape of Altona, Germany, produced the Cox model slide rule for K&E, but around 1899, Keuffel & Esser started manufacturing its own rules. To make the duplex slide rule – which was made of mahogany and white celluloid – K&E began importing large quantities of mahogany from the West Indies. They stored the logs in a lumber yard at the Hoboken factory, where they were seasoned for five years before being cut and finished into slide rules.
In 1893, K&E ran an advertisement for the new Cox model duplex slide rule in Scientific American. The advertisement carefully explained the new features of the rule, described how it worked, and noted how it differed from the Mannheim style rule. It featured an illustration of both the front and back of the slide rule, along with an explanation of how it was supposed to be used. With the emergence of new fields requiring calculations, such as electrical engineering and aviation, K&E developed new slide rules, frequently providing instruction manuals for their use.
In the early twentieth century, K&E began selling materials for making blueprints, just in time for the boom in skyscraper construction in major American cities. The development of this new product line was an extension of the company’s focus on drafting tools. The blueprint paper line continued to be refined in the 1920s and 1930s, and it led the company into more applied scientific research and development and, eventually, to the creation of a research and development (R&D) department. The reproduction of tracing paper and blueprint paper was first done with direct sunlight, then electric arc lighting. In order to improve production, K&E began experimenting with the chemical coatings used for blueprint and tracing paper as well as with the manufacture of new types of paper.
As Keuffel and Esser became more deeply involved in manufacturing, they moved to patent their refinements to established drafting and surveying tools. Both founders held patents in their own names (Keuffel had four and Esser had seven) and in the name of Keuffel & Esser; innovations developed by K&E employees were patented in the name of the company. In the 1890s and early 1900s, the partners applied for several patents on improvements to various surveying tools, including transits, levels, and surveying rods, and they also exhibited an improved steel tape at the 1893 World’s Fair in Chicago. John Paoli, an Italian-born mechanic who worked for K&E for several years in the 1890s and early 1900s, filed several patents on behalf of the company, particularly for improvements to surveyor’s transits. Keuffel’s second cousin, Wilhelm (“Willie”) L.E. Keuffel, who joined the company in the early 1880s, filed for ten patents in K&E’s name between 1900 and 1911, while Wilhelm J.D. Keuffel’s son-in-law, Carl M. Bernegau, held two patents, both for improvements to surveying equipment.
As Keuffel and Esser became more successful, and as their products became more popular, the two partners became more aggressive in defending K&E’s patents. In 1916, eight years after Keuffel’s death, the company sued former employee Eugene Dietzgen, the founder of Eugene Dietzgen Company of Chicago, for infringing on their design for a fountain pen. In 1887, Keuffel and Esser even began copyrighting product descriptions and illustrations in their catalog. In 1901, they informed their customers:
We beg to call to attention the fact that we have copyrighted this entire book, and have also separately copyrighted about four hundred of the illustrations contained in it, and much of the descriptive and explanatory matter concerning different instruments and appliances, although the general copyright of the book covers all of its contents. We have done this at considerable expense, for the purpose of protecting our patrons and the public generally from imposition at the hands of those unscrupulous dealers, who have reproduced our superior cuts and closely copied our descriptions for the purpose of making inferior articles appear to be ours or the same as ours.
Copyrighting and patent defense became increasingly common in the late nineteenth century as companies sought to protect their property rights from competitors. In 1891, Keuffel was sued by Brooklyn ink manufacturer Charles M. Higgins, who claimed that K&E had violated his copyright of the phrase “waterproof drawing ink.” Keuffel & Esser sold Higgins drawing inks (in twelve different colors, including “Black, waterproof”) and glues, but argued that copyright law did not protect labels because labels simply identified the articles on which they were placed. The U.S. Circuit Court for the Southern District of New York ruled in Keuffel’s favor, stating that “A label placed upon a bottle to designate its contents is not a subject for copyright,” and that “In order to maintain an action for an infringement of the ownership of a label … it is necessary that public notice of the registration should be given by affixing the word ‘copyright’ upon every copy of it.”
Keuffel and Esser sold their products in several ways: through in-house sales, mail order catalogs, regional salesmen, branch stores, and licensed dealers. They started with door-to-door sales, in-house sales, and mail order. They published their first catalog, a twenty-four-page booklet, in 1868. Five years later, the catalog was 123 pages long and included both surveying and drafting equipment. By the 1910s, the catalog was more than 500 pages long and listed more than 5,000 items.
Keuffel and Esser probably wrote the copy for the first few editions of the K&E catalog, and Esser, who had some drafting experience, may have done the illustrations. The large number of printers in New York City made publishing catalogs, instructional manuals, and other promotional materials relatively easy. Later catalog text was probably written by a hired copy editor.
After several years of relying on walk-in customers at the Fulton Street store and mail order sales, Keuffel and Esser began using regional salesmen in the 1880s. These men visited architectural firms, construction companies, and universities around the country, demonstrating and selling K&E products.
The two partners also opened retail stores around the country: Chicago (1891), St. Louis (1894), and San Francisco (1901). In 1908, they expanded into Canada, opening a store in Montreal. Each K&E store had a workshop, where craftsmen could make minor repairs, thus eliminating the need for customers to ship broken items back to the New York store. Like the Fulton Street flagship store, the branch stores allowed customers to test equipment before buying. Branch stores were also able to make blueprint paper in house so that, as the company promised, stock was always fresh and orders could be filled immediately. The branch stores were responsible for selling to dealers within a particular geographic region, such as stationery stores, hardware stores, and college bookstores. Distributors connected to the branch stores reported to the branch managers and did the actual selling and distribution of items.
Networking with both established and potential customers and sellers was also an important part of their business. Keuffel and Esser regularly attended trade shows, scientific and technical conferences, fairs, and expositions to meet with customers and demonstrate their products. For example, in 1904, K&E proudly announced in The Electrical Age that it had won the only grand prize for “instruments of precision, philosophical apparatus, etc” (philosophical apparatus were tools used in scientific research) at the St. Louis Exposition that year; it also won a gold medal for instruments and equipments for underground surveying. Keuffel and Esser were also members of the New York Stationers’ Board of Trade and attended annual meetings.
From the beginning, K&E advertised regularly in a wide range of trade and technical publications, including The American Book Seller; Scientific American; American Artisan (“a Weekly Journal of Arts, Mechanics, Manufacturers, Engineering, Chemistry, Inventions, and Patents”); The Technologist (“Industrial Monthly: a Practical Journal for Manufacturers, Mechanics, Builders, Inventors, Engineers, Architects”); The Manufacturer & Builder (“A Practical Journal of Industrial Progress”); The American Architect and Building News; Brick, Pottery and Glass Journal; A.H. Van Nostrand’s Engineering Magazine; Architectural and Building Monthly; Electrical Age; Stone; Marine Engineering; The Railway Age; Railroad Gazette; The National Builder; and Hardware Dealers’ Magazine. Keuffel & Esser also advertised in Puck, an English- and German-language satirical magazine published and illustrated by Austrian immigrant Joseph F. Keppler, who, like Keuffel and Esser, belonged to the Elka Park Association of the New York Liederkranz. Their presence in New York City also allowed Keuffel and Esser to network with scientific publishers, editors, and writers.
K&E’s advertisements ranged from simple statements about their location and the nature of their business to announcements for new products. In product-release advertisements, K&E usually described the product and discussed its purpose and use. Additionally, company advertisements often included a detailed drawing of the item. In some instances, the product description was copy written by K&E; in other instances, the advertisement featured a product review.
Draftsmen, surveyors, architects, building engineers, and later mechanical, electrical, and other engineers all used K&E’s products. In the decades after the founders’ deaths, numerous technical and engineering schools started buying K&E instruments for their students to use during instruction, and industrial laboratories and the federal government – especially the military – contracted with Keuffel & Esser on a regular basis from the 1910s to the 1960s. City governments frequently bought K&E equipment for public works projects, especially road-building.
Because K&E manufactured such a wide range of products, the company had many competitors over the course of a century in business. K&E had competitors in the slide rule market, in drafting and survey equipment, in blueprinting paper, and later, during the twentieth century, in optics manufacturing.
Initially, the main producers of scientific and mathematical instruments, including slide rules, were European. In 1862, five years before Keuffel and Esser launched their business, Dennert & Pape (“D&P,” later called Aristo after 1936) started producing slide rules and other measuring instruments in Germany. German pencil manufacturer A.W. Faber Castell started making drafting equipment in the 1860s and slide rules in 1884. By 1900, Faber was selling German-manufactured slide rules in the U.S. Another important German instrument manufacturer was Beck & Nestler (later called Nestler), founded in 1878; Beck & Nestler made other drafting equipment in addition to slide rules. In 1891, Reiss, Inc., began making surveying equipment as well as slide rules in Liebenwerda, Prussia. In the early 1910s, Harold Fowler, the son of Mechanical Engineer publisher William Henry Fowler, founded the English company, Fowler, and started making circular slide rules.
In the U.S., much of Keuffel and Esser’s competition came from other German immigrant entrepreneurs. One of their main competitors was Luhring & Dietzgen (later Eugene Dietzgen Company), founded in Chicago in 1885 by former K&E Midwestern sales representative and fellow German immigrant Eugene Dietzgen. Dietzgen’s rules were similar to K&E’s in design and quality, and the company was one of the largest in the U.S. after K&E. Another competitor in both the slide rule and blueprint paper businesses was Frederick Post, a German immigrant who started the Post Company in 1890 to manufacture and sell drafting, surveying, and engineering supplies after learning the business from Dietzgen. Although Post Co. sold slide rules, the firm never manufactured its own, preferring instead to import rules made by Dennert & Pape, Nestler, and Faber, and then after 1932, by Hemmi Keisanjaku of Japan. Post and his cousins Charles and Jacob Bruning also started a blueprint paper company, Post, Jacobi, & Bruning, in 1893. From the early 1890s to the 1920s, the Brunings, who were Danish immigrants, started several blueprint companies that competed with K&E in the blueprint business.
Although K&E enjoyed steady success in its first decades, the company remained relatively small until the 1890s. In 1870, Bradstreet’s Commercial Reports rated K&E as “DD,” meaning somewhere between D (“Doing business with small capital; generally meets engagements; doing well in a small way, and thought to be good for small lines”) and DE (“Not to be refused credit in all cases but caution is advised in selling”). Nine years later, in 1879, Bradstreet rated K&E “F 2 ½,” with F equaling “worth between $10,000-$20,000 estimated pecuniary strength,” and 2 ½ equaling good credit risk. By 1908, the year in which both Keuffel and Esser died, K&E had 450 employees. Nearly all of them were employed at the Hoboken factory, though a small minority worked in the branch stores and as traveling salesmen.
In 1905, K&E’s Hoboken factory was seriously damaged in a fire. Keuffel rebuilt and modernized the factory, which reopened in July 1907, just in time for the company’s fortieth anniversary. The new building on the west side of Adams covered the length of Third Street to Jefferson Street. It was made of fireproof concrete and, at 152,500 square feet, was the largest facility of its kind in the world. The new factory was Keuffel’s last major project on behalf of K&E; fifteen months later, he died at his home in Hoboken.
By the time of Keuffel’s and Esser’s deaths in 1908, their sons, Willy G. Keuffel and Otto Esser; Keuffel’s second cousin, Willie L.E. Keuffel; Willie L.E.’s son Carl W. Keuffel; and Wilhelm J.D. Keuffel’s sons-in-law, Carl M. Bergenau, Eugen Busch, and Karl Keller, had joined the family business, working their way up from salesmen and clerks to various supervisory and managerial positions. These men owned and managed K&E until its sale to Kratos Corporation in 1981.
While K&E’s success in the nineteenth century came from sales to both private and public builders, much of the company’s growth in the twentieth century was tied to government-funded projects. Keuffel & Esser did extensive work for the U.S. Army and Navy during the First and Second World Wars; they also manufactured precision measuring, sighting, and optical tools, as well as surveying and drafting equipment for New Deal-era public works projects during the Great Depression. K&E’s growth in the 1930s to 1960s paralleled the growth and development of the “military-industrial complex.” By 1965, when K&E became a publicly-traded company, it had more than 2,200 employees working in twenty-nine sales offices in sixteen states and ten factories in New Jersey, New York, Connecticut, California, Texas, Michigan, Maine, and Quebec, Canada. Yet, by the mid-1970s, the product most closely associated with the firm, the slide rule, had been rendered obsolete by the pocket calculator, and K&E stopped manufacturing rules altogether in 1975. The company donated the machine used to engrave precise lines on its mahogany slide rules to the Smithsonian Institution.
After considering – and rejecting – a series of acquisition offers in the late 1960s and 1970s, the Keuffel family, which retained ownership of seventy percent of K&E’s stock, accepted a 1981 buy-out offer from Kratos Corporation, a manufacturer of analytic devices, aircraft instruments, and computer display equipment based in La Jolla, California, for $55 million ($132 million in 2010), or $31 per share. The acquisition was poorly leveraged, and by 1984 the debt had forced Kratos into bankruptcy. InteliCoat, which manufactures coated papers, films, and specialty substrates, acquired the remaining assets of Keuffel & Esser through a series of mergers and acquisitions in the 1990s.
Keuffel & Esser was very much a “German” business. As German immigrants, the partners spoke German and most likely did so with each other and their families. Both partners spent considerable time in Germany on business and thus maintained a connection to German business practices and German culture. In 1902, after retiring from Keuffel & Esser and selling his stake in the business to Keuffel, Hermann Esser returned to Germany, where he died six years later. K&E had a tradition of hiring German craftsmen, and Hoboken’s location within the Port of New York helped guarantee a steady supply of German workers. But K&E’s “Germanness” did not prevent it from doing substantial business with the U.S. government during both World Wars. And English was probably the primary language spoken in the New York showroom, in regional retail stores, and by regional salesmen.
It is unclear how many German-born or German-speaking workers were employed at K&E, but one cannot fail to notice that many of the employees listed in the company’s in-house newsletter, the Kecoscope (keco for K’euffel & ’E’sser ’Co.), had German-sounding surnames. In 1892, when the company celebrated its twenty-fifth anniversary with a company picnic at a local park, it printed the program in both English and German – a decision that suggested that at least some of K&E’s employees (and their family members) were more comfortable reading German than English. Additionally, all of the K&E employees implicated in a handful of unusual incidents over the years were German born: for example, in 1895, K&E was embezzled by two young German-American employees, Albert Hohmann, age 24, and Harris Paulis, age 30, who stole plans, castings, telescopes, and other equipment with the intention of setting up their own rival business. In 1915, K&E was indirectly involved in a passport fraud case in which a former employee, Richard Peter Stegler, was convicted of buying an American’s birth certificate and applying for a U.S. passport in order to return to Germany under the guise of an American citizen. And Conrad Leiptau, “a German who is secretary for W. G. Keuffel, President of Keuffel & Esser, makers of mathematical instruments in Hoboken, now engaged in manufacturing range finders and periscopes for the navy,” was arrested for shouting “Hurrah for the Kaiser” in the streets of Hoboken during World War I.
Both Wilhelm J.D. Keuffel and Hermann Esser were active members of New York City’s German community, the largest in America. But they certainly did not have to cross the Hudson to be surrounded by German culture. When Keuffel and Esser arrived in the U.S. in 1867, Hoboken was already on its way to becoming one of the most “German” communities in America. In 1870, Hoboken had 20,297 residents, 10,334 of whom were foreign born; and of those immigrants, more than 5,000 came from German-speaking states, mainly Prussia, but also Bavaria, Baden, Württemberg, Hesse, and the Palatinate. By 1890, Germans and their American-born children comprised 41 percent of the city’s 43,648 residents. Twenty years later, in 1910, 26 percent of Hoboken’s 70,324 residents were either German immigrants or the American children of German-born parents.
This large German immigration was facilitated by the German shipping lines, Hamburg-America Packet Company and the North German Lloyd Steamship Company, which built piers in Hoboken in 1863 and 1864, respectively. In fact, when Hermann Esser arrived in New York on the Hamburg Brazilian Steamship Company’s ship, the S.S. Teutonia, on September 26, 1866, his ship probably docked at Hoboken. (Keuffel sailed to the U.S. on an English ship from Glasgow, Scotland, and most likely docked on the Manhattan side of the Hudson, but he would have gone through Castle Garden just as Esser did.)
When Wilhelm J.D. Keuffel died, his life was celebrated as an immigrant success story of upward mobility – a story that could “only happen in America.” As the local newspaper commented, “He came to this country a poor man and it was not until he had labored for years that he attained his success.” The newspaper also noted that Keuffel’s funeral, which was held at Hoboken’s prestigious Deutscher Club (German Club), was “largely attended as he was one of the most prominent members of the German colony in the country.”
It is unclear how much capital Keuffel and Esser brought with them to America. What is clear, however, is that they quickly ascended into the middle and professional classes of the German-American community in both New York City and Hoboken. The Keuffel and Esser families first lived in middle-class and then upper-middle-class neighborhoods in Hoboken, and the partners were active in mostly German civic, cultural, and educational organizations in both New Jersey and New York. When the Keuffels and Essers sailed to and from Europe, they traveled cabin class, not steerage.
The Essers were first listed in the local city directory in 1871, when they lived in downtown Jersey City; by 1874, the family had moved to the Jersey City Heights, a nicer neighborhood on the cliffs overlooking the Hudson River. They then moved to 56 Eighth Street in Hoboken near the newly-founded Stevens Institute of Technology.
Almost immediately after settling in Hoboken, Keuffel and Esser lived in the Second Ward, Hoboken’s upper-class district. (As bachelors, Esser and Keuffel had lived together briefly at 113 Garden Street in 1868.) The Keuffel and Esser families lived near one another, often next door or across the street, for many years, at 24, 56, and 31 Tenth Street in the late 1870s; at 188 and 190 Hudson Street in the 1880s and early 1890s, and then at 510 and 512 Hudson Street in the mid-1890s.
The Second Ward, and especially the blocks closest to the Stevens Institute, where the Keuffels and Essers lived, consisted of single-family brownstones and Victorian mansions. In a city of tenements and factories, the Second Ward stood out. It also had the fewest immigrants, including Germans, of any Hoboken neighborhood. By comparison, Keuffel and Esser’s factory was located in the heavily foreign Fourth Ward, which was populated by Irish, Italian, and Russian immigrants.
But living in the Second Ward did not necessarily mean assimilation into Anglo-American culture. Social life in Hoboken in the late nineteenth and early twentieth centuries was dominated by German immigrants. From the 1880s until 1917, the year in which the U.S. entered World War I, the city’s public schools were bilingual in German and English from kindergarten (pioneered in Hoboken by German immigrants) through Grade 12. Additionally, the city had two German-language private schools. By 1900, Hoboken had five German-language churches and one German-language synagogue, as well as dozens of German fraternal, social, cultural, homeland, and athletic organizations. In the late nineteenth and early twentieth centuries, Hoboken, as a port city, had more than twenty hotels, several of which were owned by Germans and catered to German-speaking travelers. Both Keuffel and Esser were actively involved in two of the more important German institutions in Hoboken, the Hoboken Deutscher Club (German Club) and the Hoboken Academy, a private German school.
Founded in 1857, the Hoboken Deutscher Club was one of the city’s premier social organizations. A local booster wrote of the club in 1884: “its members are composed of the very best citizens of Hoboken, with some from New York. The individual wealth of the members of this club is, in the aggregate, probably more than that of any other German club in the United States.” Its members included Dr. Hans Kudlich, an Austrian who had been a leader in the Vienna Parliament during the Revolution of 1848, Carl Christian Schurz, a Civil War general and U.S. Senator from Missouri, and William Steinway of Steinway & Sons piano company of New York.
Keuffel joined this exclusive fraternity in 1869, and Hermann Esser sat on the club’s board of trustees in the mid-1880s. Keuffel’s funeral was held at the Deutscher Club, which was located at 600 Hudson Street, one block from the Keuffel family’s home.
Recognizing the importance of education – especially engineering and technical training – to their business, Keuffel and Esser also supported several schools in Hoboken and New York City. Although it is unclear which schools the Keuffel and Esser children attended, upwardly mobile Protestant German immigrants such as Keuffel and Esser probably sent their children to the Hoboken Academy, which had been founded by Saxon immigrant Adolf Douai in 1860. Keuffel also served as president of the Academy and as trustee of the Hoboken Manual Training School, a public institution. He also sat on the advisory board of the German Hospital and Dispensary (now Lenox Hill Hospital) in New York City.
The German Hospital and Dispensary was founded by German immigrants in 1857 to serve New York City’s growing German community. Originally located on Canal Street in Kleindeutschland on the Lower East Side, the hospital moved to Second Avenue at Eighth Street in 1884, and then to Park Avenue and 77th Street in 1905, where it is presently located. As late as World War I, when the hospital’s name was changed to Lenox Hill Hospital to escape association with Germany, an estimated 95 percent of the doctors, nurses, and other staff members spoke German.
St. Matthew’s Lutheran Church, a German church established in Hoboken in 1858, was one important local German institution with which the Esser family was associated. The Keuffels were also Lutheran, but it unclear whether they attended St. Matthew’s or St. John the Baptist (later the Evangelical Lutheran St. John’s Church), which was established in 1889.
The Keuffel and Esser families were also active in the Elka Park Association resort in Greene County, New York, in the Catskills. A collection of twenty-one vacation homes, Elka Park was developed by the New York Liederkranz in 1890. Keuffel built a two-and-a-half story Queen Anne Victorian- style house for his family there in 1893, and Esser built a two-and-a-half story Colonial Revival bungalow for his family in 1894. An additional Elka Park house associated with the Keuffel family was built in 1896.
The Liederkranz had been founded in 1847 by twenty-five German immigrants interested in promoting and preserving German culture through music. By the 1890s, it had grown to more than 1,500 members, most of whom were successful businessmen and professionals. Active members paid $24 in annual dues and sang in the men’s choir, while passive members paid $40 per year in dues and used the club primarily as a socializing and networking arena. Piano manufacturer William Steinway was president from 1867 until 1896. Chemist Jacob Hasslacher, chemist Frederick W. Fink, and Puck owner and illustrator Joseph Keppler were among those club members with summer homes at Elka Park.
Keuffel also belonged to several non-German associations, including the Hoboken Board of Trade (equivalent to the Chamber of Commerce), the Stationer’s Board of Trade of New York, and the Technical Society of New York.
Both Keuffel and Esser were active in civic life, but neither was involved in local politics in Hoboken. Most middle- and upper-class Germans in Hoboken were Republican, and it is likely that they were as well.
Although Keuffel and Esser married and raised their families in the U.S., both made sure that their children grew up with close ties to Germany. The partners took their wives and children with them on extended business trips, and their children spoke German. Two of Keuffel’s daughters married German men: Louise Keuffel’s husband, Carl M. Bernegau, was born in Rheinberg, Rhineland Province, Prussia, in 1866; and Ottilie Keuffel’s husband, Eugen Busch, was born in Remscheid, Rhineland Province, Prussia, in 1867. A third Keuffel daughter, Margarethe, married a man from German-speaking Switzerland; her husband, Karl Keller, was born in Zurich in 1880. Willy G. Keuffel’s wife, Ida, was born in New York in 1878 to German immigrant parents.
Other members of the Keuffel family maintained close ties to Germany and were active members of the German-American community in both New York City and Hoboken, even after World War I. Carl M. Bernegau, president and treasurer of K&E in the 1940s, was a member of the Hoboken German Club and the Hexamer Riding Academy, a local German equestrian club. He was also a trustee of the Lenox Hill Hospital in New York, just as his father-in-law had been. In the 1920s and 1930s, the Bernegaus visited Germany approximately every other year. Keuffel’s wife Bertha continued to make frequent trips to Germany after his death. Moreover, Ottilie and Eugen Busch lived in Europe for many years: in Riga, Latvia, and in Russia in the 1900s; in Königsburg, East Prussia, in the 1910s and 1920s; and in Merano, Italy, in the 1930s.
The Stevens Institute of Technology was one non-German institution with which the Keuffels maintained close ties. W.L.E. Keuffel’s sons, Carl and Adolph William, attended Stevens, with Carl graduating in 1911 and Adolph in 1914. Both worked at K&E for most of their careers: Carl served as president from 1950 until 1961 and Adolph oversaw slide rule production from 1920 until 1940. Carl Bernegau was a trustee of Stevens for many years, and, after moving to Orange, New Jersey, he donated the family’s home at 809 Castle Point Terrace to the college for use as a dormitory. Carl W. Keuffel, president of K&E in the 1950s, received an honorary degree from Stevens in 1958.
Keuffel & Esser was a German-American business in the fullest sense of the term. German immigrants Wilhelm J. D. Keuffel and Hermann Esser built a lasting business in the United States but always maintained close ties to Germany, mainly for business reasons but also for personal ones as well. Ultimately, near the end of his life, Hermann Esser chose to return to Germany, where he died. The two founders had arrived in the U.S. at a time of high German immigration and they settled in a community, Hoboken, that was dominated by German immigrants and German immigrant culture. During the forty-plus years that Keuffel lived in Hoboken, the number of German immigrants never dropped below 25 percent of the city’s population (and sometimes it even reached as high as 41 percent). The city’s schools were bilingual in German and English, and the community had several German language churches, as well as many German-owned businesses and social organizations. It was possible for a German immigrant to live and work in Hoboken and rarely (if ever) need to speak English.
In terms of business practices, Wilhelm Keuffel and Hermann Esser certainly spoke English (Keuffel probably learned it in Manchester, if he hadn’t already studied it in school in Germany) in order to sell to their customers. Going door-to-door to architects’ and builders’ offices in Manhattan in the late 1860s required a good command of English, and it is probable that English was the primary language of business at K&E early on. Still, the large number of German craftsmen in the New York City area may have meant that some parts of the Hoboken factory were either German-speaking or bilingual. K&E also advertised extensively in English, and published numerous instructional manuals in English. Although the founders were German, they did not limit themselves to selling just to Germans.
Keuffel and Esser succeeded as entrepreneurs because they saw a demand for high-quality scientific instruments and responded with high-quality products, first through imports and then through domestic manufacture. Between 1867 and 1908, Keuffel and Esser built one of the largest instrument manufacturing firms in the world and introduced the slide rule to the United States. The founders also improved on the design of numerous drafting and surveying tools, and encouraged their successors to emphasize the research and development of new products.
For many years, Keuffel & Esser was one of the largest producers of slide rules in the world, and their rules were cherished as the expensive and essential tools of thousands of architects and engineers. Traditionally, an engineer would buy a K&E slide rule in college or soon thereafter and use it for the duration of his career. As slide rules were replaced by electronic pocket calculators in the 1970s, a handful of engineers who had come of age using slide rules began collecting them. The Oughtred Society, an association of slide rule collectors, was formed in 1991 and is based in Emeryville, California, in the San Francisco Bay Area. In 2005, the MIT Museum in Cambridge, Massachusetts, was given InteliCoat Technologies’ unparalleled collection of 600 K&E slide rules. K&E instruments are also found in other museums, including the Smithsonian Institution.
The end of the slide rule did not have to spell the end of Keuffel & Esser; yet, by the late 1970s, K&E’s most visible product had been rendered obsolete by new technologies, and the company faced stiff competition in the specialty paper market. Given the opportunity to sell out, the Keuffel family did, ending more than a century of family ownership and control. Now, this once successful German-American business is known primarily to collectors and an aging generation of engineers.
 New York City Landmark Preservation Commission, April 26, 2005, Designation List 362, LP-2178, p. 1, Summary; “Partners in Creating the First Century of K&E, 1867-1967,” p. 3, (accessed on July 17, 2012). The booklet also states that Keuffel & Esser was the first firm to specialize in scientific instrument sales and manufacturing.
 There are three villages named Walbeck in Germany today; two are in Saxony-Anhalt, the third is part of the municipality of Geldern, North Rhine-Westphalia. Of the two in Saxony-Anhalt, one is in the Börde district slightly northwest of Magdeburg; the other is part of the municipality of Hettstedt in the Mansfeld-Südharz district and is further south, closer to Halle. When Keuffel was born, the two Saxon Walbecks were part of the Prussian province of Saxony, and it is unclear which village was his birthplace. In an interview with Keuffel’s great-grandson, Gerd Keuffel, Keuffel said that his great-grandfather worked in a hardware store in Braunschweig, which is near the Börde Walbeck. See Gary S. Flom, “Interview with Gerd Keuffel,” Journal of the Oughtred Society (vol. 14, no. 2, 2005): 58, (accessed on August 26, 2012).
 George von Skal, A History of German immigration in the United States and successful German-Americans and their descendents (New York, NY: F.T. & J.C. Smiley, 1908), “William Keuffel,” p. 149; The National cyclopaedia of American biography: being the history of the United States, vol. 17, edited by George Derby and James Terry White (New York, NY: James T. White, 1920), p. 187, notes the names of Keuffel’s parents but does not mention his father’s occupation or anything else about the family; Obituary, Keuffel, New York Times, October 3, 1908, p. 9. The date of Keuffel’s immigration to England is unknown, although it was sometime between 1857 and1866. Keuffel immigrated to the U.S. on July 15, 1866, sailing on the S.S.Iowa from Glasgow, Scotland, and he became a naturalized U.S. citizen on March 9, 1874, in Hudson County, New Jersey. See Wilhelm Keuffel, May 17, 1895, National Archives and Records Administration (NARA), Washington D.C., Passport Applications, 1795-1905: ARC Identifier 566612/MLR Number A1 508; NARA Series: M1372; Roll #: 444, located at Ancestry.com on July 12, 2012. “Marine Intelligence,” New York Times, July 16, 1866, notes that the steamship Iowa departed Glasgow on July 1, and arrived in New York on July 15, 1866, with 638 passengers. “Keuffel, William, drawing matl, 71 Nassau, h 113 Garden, Hoboken,” and “Keuffel and Esser, drawing matl, 71 Nassau,” Trow’s New York Directory 1868-1869, vol. 1, A-Kup, compiled by H. Wilson, vol. LXXXII, for the year ending May 1, 1869 (New York, NY: John F. Trow, 1869), p. 586, is the first mention of Keuffel in a local city directory. He does not appear in Hoboken directories until 1876, please see “Keuffel, William, math insts, h 17 Tenth St, Hoboken,” Gopsill’s Jersey City and Hoboken City Directory, for the year ending April 30, 1876, pt. 2, H-R (Jersey City, NJ: James Gopsill, 1876), p. 351.
 Bertha was eighteen years old and Wilhelm was thirty-three years old at the time of their marriage. It is unclear how they met. They were married by Rev. J.G. Eberhard in St. Louis. See Missouri Marriage Records, 1805-2002, located at Ancestry.com on February 5, 2013. Eberhard was pastor at the Independent Evangelical Church of the Holy Ghost in St. Louis at the time of the Keuffels’ marriage. See John Thomas Scharf, History of St. Louis City and County from the Earliest Periods to the Present Day: Including Biographical Sketches of Representative Men, volume 2 (St. Louis, MO: L. H. Everts & Company, 1883), pp. 1731-32. Information on Bertha Keuffel’s date of death could not be found. John Schneeberger was a shoemaker who was born in Hesse-Darmstadt. In 1860, he owned $300 worth of real estate and his personal estate was valued at $1,000. This information on Schneeberger comes from the Eighth Census of the United States, Year: 1860; Census Place: St. Louis Ward 5, St. Louis (Independent City), Missouri; Roll: M653_651; Page: 290; Image: 294; Family History Library Film: 803651, located at Ancestry.com on February 5, 2013. Schneeberger and his wife Margaret had four daughters; Bertha was the eldest. In 1860, the Schneeberger household also included a Maine-born female servant, an Irish-born drayman and an Irish-born laborer, a Dutch-born shoe maker, a Bavarian-born shoemaker, and an 18-year old apprentice shoemaker named Jacob Schneeberger, also from Hesse-Darmstadt, possibly a brother. By 1870, the Schneebergers had moved to St. Louis’ Ward 3, and John Schneeberger was listed in the 1870 census as a boot and shoe manufacturer with real estate holdings valued at $2,500 and personal property valued at $10,000. By 1870, the Schneebergers had six daughters and were living in a single-family home with a domestic servant from Osnaburg(?), Ninth U.S. Census, Year:1870; Census Place: St. Louis Ward 3, St. Louis, Missouri; Roll: M593_812; Page: 2A; Image: 7; Family History Library Film: 552311, located at Ancestry.com on February 5, 2013. The Schneebergers were prosperous enough for Bertha and her mother to travel to Europe: the two returned to New York on November 14, 1870, on the ship Cimbria, New York Passenger Lists, Year: 1870; Arrival: New York, United States; Microfilm Serial: M237; Microfilm Roll: 336; Line: 35; List Number: 1057. The purpose of the trip is unknown, and it is unclear why they were not accompanied by other family members.
 All of the Keuffel children were born in Hoboken, except for Ottilie, who was born in Suderode (possibly Bad Suderode), Germany; Ottilie Keuffel, May 21, 1902, National Archives and Records Administration (NARA); Washington D.C.; Passport Applications, 1795-1905; Collection Number: ARC Identifier 566612/MLR Number A1 508; NARA Series: M1372; Roll #: 600. A number of ship manifests list Margarethe Keuffel as “Gretchen.” There was also a Herman Keuffel, born on October 24, 1886, in Hoboken, to father Wilhelm J.D. Keuffel, age 48, and mother Bertha C. Schneeberger, age 33, New Jersey, Births and Christenings Index, 1660-1931, located at Ancestry.com on July 12, 2012. A Keuffel family tree registered with Ancestry.com includes a Hermann Keuffel (October 24, 1886-May 16, 1887), and a Martha Keuffel (September 22, 1876-January 6, 1879). The National cyclopaedia of American Biography, volume 31 (New York, NY: James T. White & Co., 1944), p. 361, notes Willy G. Keuffel’s death in 1942; Social Security Death Index for Otilie Keuffel Busch, Social Security Number 150-42-1894, Number: 150-42-1894; Issue State: New Jersey; Issue Date: 1966, and Margaret Keller, Social Security Number: 139-44-1771; Issue State: New Jersey; Issue Date: 1966-1867, also located at Ancestry.com on February 11, 2013.
 “William Keuffel Buried To-Day,” Jersey Journal, October 3, 1908, p. 6, and Obituary, Keuffel, New York Times, October 3, 1908, p. 9, note that Keuffel died at his home, 512 Hudson Street, Hoboken, which had served as the Esser family home until he retired and returned to Germany, Boyd’s Jersey City and Hoboken Directory 1901-1902, pt. 1, A-G (Jersey City, NJ: W.H. Boyd, 1901), p. 196, lists “Esser, Herm, treas, Keuffel and Esser, h 512 Hudson, H”; this is the last listing for Hermann Esser in Hoboken.
 Hermann Esser, March 26, 1902, National Archives and Records Administration (NARA); Washington D.C.; Passport Applications, 1795-1905; Collection Number: ARC Identifier 566612/MLR Number A1 508; NARA Series: M1372; Roll #: 594, located at Ancestry.com on July 12, 2012, states that Esser sailed from Hamburg on the S.S. Teutonia on September 26, 1866, and was naturalized in Hudson County, New Jersey, on April 3, 1877. Although Esser does not appear in Hoboken city directories until 1875, Trow’s New York City Directory for 1868-1869indicates that he was living in Hoboken as early as 1868, please see “Esser, Herman, drawing matl, 71 Nassau, h 113 Garden, Hoboken,” Trow’s New York Directory 1868-1869, vol. 1, A-Kup, p. 332. He then moved to Jersey City in 1871 before returning to Hoboken in 1875, “Esser, Hermann, math insts, h Newark n Passaic av, HC [Hudson County],” Gopsill’s Jersey City and Hoboken City Directory, for the year ending April 30, 1871, pt. 1, A-G (Jersey City, NJ: James Gopsill, 1871), p. 178. “Esser, Hermann, h 56 Eighth St, Hoboken,” Gopsill’s Jersey City and Hoboken City Directory, for the year ending April 30, 1875, p. 1, A-F (Jersey City, NJ: James Gopsill, 1875), p. 201, is the first mention of Esser in Hoboken.
 Keuffel served as a witness to the Essers’ marriage, see St. Matthew’s Trinity Lutheran Church, Record Book 1, 1856-1875, Marriages: February 22, 1857-March 11, 1874, p. 354, “1869,” entry 322. Otto Esser was born in Jersey City during the time his parents lived there (1871-74), Otto Esser, October 29, 1896, National Archives and Records Administration (NARA); Washington D.C.; Passport Applications, 1795-1905; Collection Number: ARC Identifier 566612/MLR Number A1 508; NARA Series: M1372; Roll: # 477. Klara Esser was born in Hoboken. Although most government records spell Klara Esser’s name with a “C,” in one passport application she spelled her name with a K, Klara Esser, November 13, 1900, U.S. National Archives and Records Administration (NARA); Washington D.C.; Passport Applications, 1795-1905; Collection Number: ARC Identifier 566612/MLR Number A1 508; NARA Series: M1372; Roll #: 566. The death dates of the Esser children cannot be determined.
 Charles E. Smart, The Makers Of Surveying Instruments in America Since 1700, vol. II (Troy, NY: Regal Art Press, 1962), p. 224, says that Esser returned to Bad Godesberg am Rhein, Germany, on April 23, 1902, and died there on April 16, 1908; this information comes from his correspondence with Ward H. Bolter, a K&E employee in Hoboken; “Herman Esser Dies in His Home in Germany,” Hoboken Observer, April 16, 1908, p. 10. Boyd’s Jersey City and Hoboken Directory, 1903-04, pt. 2, H-R, p. 365, lists Keuffel as living at 512 Hudson Street, Esser’s last recorded residence in 1901, please see “Esser, Hermann (K&E), h 512 Hudson,” Boyd’s Jersey City Hoboken Directory, 1901-1902, pt. 1, A-G, p. 196. The fact that Esser turned over his home to his old partner suggests that he did not intend to return to the U.S. It is unclear when Bertha Esser died.
 Flom, “Interview with Gerd Keuffel,” Journal of the Oughtred Society, p. 58, describes Keuffel’s employment at the Ravené Company and suggests his reasons for immigrating. Little is known about Keuffel’s and Esser’s work at Ravené. In the U.S., Keuffel might have worked as a traveling salesman for Ravené, which would explain how he came to meet Bertha Schneeberger in St. Louis, but this is only conjecture. Nothing is known about the kinds of capital, connections, or resources that Keuffel and Esser brought with them to the U.S. Likewise, it is unclear whether they decided to start their own business before they left Europe or after they arrived in New York.
 The population of Hoboken grew from 9,662 in 1860 to 20,297 in 1870, an increase of 262 percent; by 1910, Hoboken had more than 70,000 residents. Hoboken was rural but not particularly agricultural in the mid-nineteenth century. The land that encompasses Hoboken was bought by Col. John Stevens beginning in 1784; Stevens developed a recreational area called the Elysian Fields at the northeastern end and ferried New Yorkers across the Hudson River to picnic on his property. After Stevens’ death, his heirs formed the Hoboken Land & Development Company in 1839 and sold lots for residential and industrial development, but Hoboken was not built up until the early twentieth century. See Daniel Van Winkle, History of Municipalities of Hudson County, 1630-1923, vol. 1, Historical-Biographical (Chicago, IL and New York, NY: Lewis Historical Publishing Co., 1924), p. 287.
 All current values (in 2010 USD) are based on Samuel H. Williamson, “Seven Ways to Compute the Relative Value of a U.S. Dollar Amount, 1774 to present,”MeasuringWorth, 2011, using the Consumer Price Index.
 “Partners in Creating the First Century of K&E, 1867-1967,” p. 3; Smart, The Makers Of Surveying Instruments In America Since 1700, vol. I, p. 93, gives the dates of the founding and incorporation.
 “Partners in Creating the First Century of K&E, 1867-1967,” p. 6, notes that Keuffel won a design award from the American Institute in 1869.
 Keuffel applied for passports in 1879, 1895, 1902, 1904, 1905, and 1907, while Esser applied for passports in 1877, 1881, 1885, 1891, 1900, and 1902, U.S. Passport Applications, 1795-1925, National Archives and Records Administration (NARA), Washington D.C., located at Ancestry.com on September 4, 2012.
 “To our friends and patrons,” Keuffel & Esser Catalogue and Price List (New York, NY: Keuffel & Esser, 1881, 10th edition), Introduction, Clark McCoy and Michael O'Leary, K&E Catalogs, (accessed on August 19, 2012).
 “To our friends and patrons,” Keuffel & Esser Catalogue and Price List (New York: Keuffel & Esser, 1883, 12th edition), Introduction, Clark McCoy and Michael O'Leary, K&E Catalogs. K&E also did some manufacturing in Germany, see “Barometer, aneroid wall model 512-1, made by Keuffel & Esser Co., New York, n.d., ca. 1875-1890,” which reads “Made in Germany,” Hoboken Historical Museum, (accessed on February 9, 2013).
 New York City Landmark Preservation Commission, April 26, 2005, Designation List 362, LP-2178, p. 6, “Notes,” footnote no. 4. “Partners in Creating the First Century of K&E, 1867-1967,” p. 6, notes locations on Dutch Street and 111 Fulton Street that are not included in the New York City Landmark Preservation Commission report. Trow’s New York Directory 1868-1869, vol. 1, A-Kup, p. 586, includes the first K&E listing in a New York City directory; it lists “Keuffel & Esser, drawing matl,” at 71 Nassau Street.
 New York City Landmark Preservation Commission, April 26, 2005, Designation List 362, LP-2178, p. 3.
 “Partners in Creating the First Century of K&E, 1867-1967,” p. 6. U.S. Indexed County Land Ownership Maps, 1860-1918, “H Esser,” Collection Number G&M 15, Roll Number 15, located at Ancestry.com (accessed on July 16, 2012), shows that one H Esser had bought a lot in Hoboken in 1873. Keuffel & Esser was secretive about its sources of materials and suppliers and did not advertise this information in its catalogs. Robert Parrish, Antique Surveying Equipment, “Keuffel & Esser Corporation Historical Timeline,” suggests that in 1876, “instruments [were] added to sales line. Most likely these were made by Stackpole & Brother Instruments,” but there is no evidence for this, (accessed on February 9, 2013). Stackpole & Brother Instruments was founded by Irish immigrants William and Robert Stackpole in 1843 and manufactured mechanical engineering instruments at 41 Fulton Street. Stackpole & Brother Instruments was not so much a K&E competitor as a potential supplier.
 New York City Landmark Preservation Commission, April 26, 2005, Designation List 362, LP-2178, p. 3, notes that the land owner of 127 Fulton Street was the Reformed Protestant Dutch Church, which had owned the lot since 1791. “Building Intelligence,” The Manufacturer and Builder: A Practical Journal of Industrial Progress, May 1, 1884 (vol. 16, no. 5), p. 104, notes that “Lederle & Co. have plans in hand for a four-story and basement brick factory, 100 by 46 by 110 by 40 feet, L shape, to be erected on the corner of Adams and Third streets, Hoboken, J.J., for Keuffel & Esser, manufacturers of drawing materials, at a cost of about $85,000.” Hoboken Historical Museum exhibit, “Surveying the World, Keuffel & Esser + Hoboken, 1875-1968,” on exhibit January-December 2010, summary located at http://www.hobokenmuseum.org/exhibitions/main-gallery/past-exhibitions/keuffel-and-esser-2010 (accessed on February 11, 2013).
 New York City Landmark Preservation Commission, April 26, 2005, Designation List 362, LP-2178, p. 3.
 Thirteenth Census of the United States, 1910, vol. 3, Population Reports by States, Nebraska-Wyoming: New York, Section 2, Chapter 1, Table 13, “Foreign White Stock, by Nationality, for Cities of 100,000 or More” (Washington, D.C.: Government Printing Office, 1913), p. 216. New York City had 724,704 Germans, 19.3 percent of the city’s population, while immigrants from Russia, most of them Jews, numbered 733,924 in 1910.
 Stanley Nadel, Little Germany, Ethnicity, Religion and Class in New York City, 1845-80 (Urbana, IL and Chicago, IL: University of Illinois Press, 1990), p. 41; Christina A. Ziegler-McPherson, Immigrants in Hoboken, One-Way Ticket, 1845-1985 (Charleston, SC: The History Press, 2011), chapter 2, “Little Bremen,” pp. 36-54.
 Nadel, Little Germany, pp. 63-67.
 Ziegler-McPherson, Immigrants in Hoboken, p. 43.
 “Partners in Creating the First Century of K&E, 1867-1967,” p. 6; New York City Landmark Preservation Commission, April 26, 2005, Designation List 362, LP-2178, p. 2.
 An advertisement in Scientific American Building Edition, March 1, 1886 (vol. 1, no. 5), p. 134, describes a K&E architects’ and builders’ level that sold for $45 (approximately $1,000 in 2010).
 Robert D. Tamilia, “The Wonderful World of the Department Store in Historical Perspective: A Comprehensive International Bibliography Partially Annotated” (May 2002) (accessed on February 9, 2013).
 The Editors, “An Interview with Jack Burton and Gordon Anthony: The End of the Slide Rule Era at Keuffel & Esser – Part 1,”Journal of the Oughtred Society (vol. 7, no. 2, Fall 1998), pp. 19-20, (accessed on August 26, 2012), describes the division in types of products.
 Hermann Esser, “Draughtsman's Alphabets, A Series of Plain and Ornamental Alphabets Designed Especially for Engineers, Architects, Draughtsmen, Engravers, Painters, Etc.” (New York, NY: Keuffel & Esser, 1869).
 “Partners in Creating the First Century of K&E, 1867-1967,” p. 9, p. 10.
 The Smithsonian National Museum of American History has several K&E compasses, levels, and transits, please see “Keuffel & Esser,” NMAH Physical Sciences Collection, Surveying & Geodesy (accessed on August 25, 2012). K&E equipment can also be found in the Peary-MacMillan Arctic Museum at Bowdoin College in Brunswick, Maine, please see “Polar Pathways, 1906- 84 N 74 W: Timely Observations,” (accessed on August 25, 2012).
 Florian Cajori, “Notes on the History of the Slide Rule,” The American Mathematical Monthly, vol. 15, no. 1 (January 1908), pp. 1-5, notes that although the slide rule had been used in the U.S. in the eighteenth century, it was not until K&E began importing Mannheim rules that the device became popular. Cajori incorrectly states (on page 4) that K&E began importing the Mannheim rules in 1888 and that they began manufacturing them in Jersey City in 1895.
 This is according to the 1881 catalog, Keuffel & Esser Catalogue and Price List (New York, NY: Keuffel & Esser, 1881, 10th edition), Clark McCoy and Michael O'Leary, K&E Catalogs, (accessed on August 19, 2012).
 “Slide Rule History,” The Oughtred Society, (accessed on February 20, 2013), says that George Fuller of Ireland and Edwin Thacher independently invented the cylindrical calculator in 1878 and 1881, respectively, and that K&E manufactured the Thacher calculator. “Thacher, Edwin (1839-1920),” in Diana H. Hook and Jeremy M. Norman, Origins of Cyberspace, A Library on the History of Computing, Networking, and Telecommunications (Novato, CA: Norman Publishing, 2002), also lists Keuffel & Esser as the manufacturer of the Thacher calculator. Bob Otnes, “Thacher Notes,” Journal of the Oughtred Society (vol. 2, no. 1, March 1993), p. 21, (accessed on February 24, 2013), says that Thacher sold or assigned his patent rights to K&E sometime between 1881 and 1890. Please also see Wayne Feely and Conrad Schure, “Thacher Slide Rule Production,” Journal of the Oughtred Society (vol. 3, no. 2, September 1994) (accessed on February 24, 2013).
 “Partners in Creating the First Century of K&E, 1867-1967,” p. 11; “Slide Rule Built Thriving Concern, Keuffel & Esser Celebrates its 100th Anniversary,” New York Times, July 30, 1967, p. 130. See Patent No. 460930, issued on October 6, 1891, to William Cox, assignor Keuffel and Esser, for an engineer’s slide. Nothing is known about the arrangement Cox made with K&E for the patent on the engineer’s slide rule.
 Based on his analysis of K&E catalogs, Bob Otnes argues that K&E did not actually manufacture its own slide rules until about 1899; instead, it imported European rules, usually made by D&P, and sold them, see Bob Otnes, “Keuffel & Esser, 1880-1899,” Journal of the Oughtred Society (vol. 10, no. 1, Spring 2001): 18-29 (accessed on August 26, 2012); “Dennert & Pape/ARISTO – Data and Product Timeline,” Slide Rule Museum (accessed on August 26, 2012).
 “Partners in Creating the First Century of K&E, 1867-1967,” p. 11, “The Day the Slide Rule Arrived.”
 “The ‘Duplex’ Slide Rule,” Scientific American, August 12, 1893 (vol. LXIX, no. 7), p. 101.
 For instance, please see “Power Computing Slide Rule,” International Marine Engineering, March 1, 1913 (vol. 18, no. 3), p. 136, “Engineering Specialties,” which introduced a new rule for computing the power and dimensions of steam, gas and oil-powered engines. The Hoboken Historical Museum’s Keuffel & Esser collection contains dozens of manuals on the use of slide rules and other K&E tools, please see Hoboken Historical Museum (accessed on September 3, 2012).
 “Blueprinting Machine, New Tools of the Month, A Record of New Tools and Appliances for Machine Shop Use,” Machinery, June 1, 1904 (vol. 10, no. 10), p. 562. An early photograph of the rebuilt 127 Fulton Street building, circa 1892, shows blueprint racks hanging off the front of the building, “Partners in Creating the First Century of K&E, 1867-1967,” p. 15.
 “Partners in Creating the First Century of K&E, 1867-1967,” pp. 21-23, “Progress despite the Depression,” (accessed on July 17, 2012). The Editors, “An Interview with Jack Burton and Gordon Anthony: The End of the Slide Rule Era at Keuffel & Esser – Part 1,” p. 21, notes more than 100 employees devoted to pure research in addition to applied R&D work.
 Osborne I. Price, “Keuffel & Esser Patents,” Journal of the Oughtred Society (vol. 2, no. 1, March 1993): 34-37, (accessed on August 26, 2012), notes 32 patents issued between 1891 and 1937 relating to slide rules alone.
 Please see Patent No. 307203, issued on October 28, 1884, for a stretcher frame; Patent No. 702439, issued on June 17, 1902, for a tape reel; Patent No. 138896, issued on May 13, 1873, for improvements to a drawing board; and Patent No. 684437, issued on October 15, 1901, for a drawing pen; as well as Patents No. D28024, issued on December 14, 1897, for the design of a bottle; Patent No. 347927, issued on August 24, 1886, for an extension tripod; Patent No. D22295, issued on March 14, 1893, for the design of a fork for dividers; Patent No. 152985, issued on July 14, 1874, for an improvement to drawing pens; Patent No. 494132, issued on March 28, 1893, for a draftsman’s divider; Patent No. 384899, issued on June 19, 1888, for an ink-supplying device; and Patent No. 431568, issued on July 8, 1890, for a measuring scale.
 Patent No. 138896, issued on May 13, 1873, for improvements to a drawing board, and Patent Nos. 453158, 453159, and 453160, all issued on May 26, 1891, for improvements to engineer’s transits, filed by John Paoli, assignor Keuffel & Esser. “Partners in Creating the First Century of K&E, 1867-1967,” p. 10.
 Please see Patent Nos. 453158, 453159, and 453160, all issued on May 26, 1891, for improvements to engineer’s transits, filed by John Paoli, assignor Keuffel & Esser. Paoli was born December 29, 1859, in San Ginugnano, Siena, Italy. He immigrated and settled in Hoboken in 1883; he became a U.S. citizen on March 31, 1893, John Paoli, June 9, 1897, National Archives and Records Administration (NARA); Washington D.C.; Passport Applications, 1795-1905; Collection Number: ARC Identifier 566612/MLR Number A1 508; NARA Series: M1372; Roll #: 489, located at Ancestry.com on July 18, 2012.
 Patents filed by Willie L.E. Keuffel and Carl M. Bernegau. Please also see Price, “Keuffel & Esser Patents,” Journal of the Oughtred Society (vol. 2, no. 1, March 1993), pp. 37.
 Federal Reporter, Cases Argued and Determined in the Circuit Courts of Appeal and the District Courts of the United States, vol. 232, June-August 1916 (St. Paul, MN: West Publishing, 1916), pp. 729-30, Keuffel & Esser v. Eugene Dietzgen Co. “Who’s Who, Past and Present,” The International Slide Rule Museum, notes that Eugene Dietzgen was a former K&E sales representative who started his own drafting instruments manufacturing business in Chicago in 1885 (accessed on August 26, 2012).
 “Keuffel & Esser Catalogue and Price List (New York, NY: Keuffel & Esser, 1901, 30th edition), p. vi, “Special Notice,” Clark McCoy and Michael O'Leary K&E Catalogs (accessed on August 19, 2012).
 Higgins v. Keuffel, 140 U.S. 428 (1891), (accessed on August 15, 2012); “Commissioner of Patents Simonds Makes an Important Decision,” Boston Herald, January 26, 1892, p. 4; “Keuffel & Esser Catalogue and Price List (New York, NY: Keuffel & Esser, 1913, 34th edition), p. 263; Clark McCoy and Michael O'Leary, K&E Catalogs; “Higgins Inks and Adhesives,” (accessed on August 22, 2012).
 “Partners in Creating the First Century of K&E, 1867-1967,” p. 6, p. 9, p. 20. The 1913 catalog, for instance, had 566 pages and thousands of items, please see “Catalog and Price List of Keuffel & Esser” (New York, NY: Keuffel & Esser, 1913, 34th edition), (accessed on August 22, 2012).
 W.E. Holcomb, “Advancing the Expense Money, Does it Pay, Should the House Provide This or the Salesman?,” Hardware Dealers’ Magazine, October 1, 1911 (vol. 36, no. 4), p. 735. It is unclear from the article whether K&E paid its salesmen a commission in addition to a salary; Holcomb was a K&E employee.
 New York City Landmark Preservation Commission, April 26, 2005, Designation List 362, LP-2178; “Catalog and Price List of Keuffel & Esser” (New York, NY: Keuffel & Esser, 1913, 34th edition), p. vii, “To Our Patrons,” (accessed on August 22, 2012); Crocker & Langley San Francisco Directory 1900 does not list Keuffel & Esser whereas Crocker & Langley San Francisco Directory 1901 does list the firm at 303 Montgomery Street (San Francisco, CA: H.S. Crocker Co., 1901), p. 999. Announcement by Keuffel & Esser Co. of the opening of the Montreal Branch House, October 1908,” Hoboken Historical Museum, (accessed on February 8, 2013). “Partners in Creating the First Century of K&E, 1867-1967,” Keuffel & Esser anniversary booklet (New York, NY: Keuffel & Esser, 1967), p. 15, says that “in 1900 K&E reached the Pacific with a branch in San Francisco.”
 The Editors, “An Interview with Jack Burton and Gordon Anthony: The End of the Slide Rule Era at Keuffel & Esser – Part 1,” pp. 18-24, notes the structure of K&E’s sales operations and the changes it underwent in the 1950s and 1960s. The Editors, “An Interview with Jack Burton and Gordon Anthony: End of the Slide Rule Era at Keuffel and Esser – Part III,” Journal of the Oughtred Society (vol. 8, no. 2, Fall 1999): 27-32, (accessed on February 24, 2013), notes K&E’s policy of giving new slide rules to customers who had problems with their rules, regardless of the cause of the problem (see p. 28).
 For instance, please see “The Fair of the American Institute,” The Technologist, or Industrial Monthly, December 1, 1870 (vol. 1, no. 11), p. 298.
 “Trade News,” The Electrical Age, November 1, 1904 (vol. 31, no. 5), p. 384.
 The American Bookseller, January 17, 1891 (vol. 29, no. 2), p. 32.
 “History, Liederkranz Society of New York,” (accessed on August 22, 2012); “The William Steinway Diary, 1861-1896,” Smithsonian Institution, (accessed on August 22, 2012). Elka Park was a community of vacation homes in the Catskills owned by prominent members of the singing society.
 Advertisement at bottom right corner entitled: “Drawing materials for Architects, Engineers, Surveyors, and Draughtsmen,” American Artisan, November 24, 1869 (vol. 9, no. 21), p. 336; “Keuffel & Esser’s Architects and Builders’ Level,” Scientific American Building Edition, March 1, 1886 (vol. 1, no. 5), p. 134.
 “Personal and Social” column, Wisconsin State Journal, September 30, 1901, p. 5, notes the visit of F.B. Fink of Keuffel & Esser and W. M. Duncan of Eugene Dietzgen Company to the University of Wisconsin. “Orders to Naval Officers,” Washington Post, December 14, 1905, p. 1, and “Naval Orders,” Washington Post, November 20, 1915, p. 11, note the assignment of Navy personnel to K&E’s Hoboken factory to oversee production for naval contracts. “K+E Ninety Years Young in Instrument Making,” New York Times, August 20, 1957, p. 35, notes such Fortune 500 customers as Du Pont, Westinghouse, Raytheon, General Electric, and Maryland Shipbuilding, as well as the federal government.
 For instance, please see New York Evening World, November 22, 1894, p. 7, column entitled “Central Park, Improvement of, between 7th and 8th Avenues, from 104th to 110th Streets,” which notes that New York City had bought cross-section paper for $16 and drawing materials for $13.53 from K&E.
 “Dennert & Pape/ARISTO – Data and Product Timeline,” International Slide Rule Museum (accessed on August 26, 2012).
 Denise M. Gustavson, Necessity is the Mother of All Invention (Modern Reprographics, June 2000), timeline reproduced as “Slide Rule Startups,” International Slide Rule Museum, (accessed on August 26, 2012).
 Bradstreet’s Commercial Reports embracing the Bankers Merchants Manufacturers and Others in the United States and the Dominion of Canada, vol. XXVII, July 6, 1870, “New York City,” no page number, no publisher noted; The Mercantile Agency Reference Book (and Key) containing ratings of the Merchants, Manufacturers, and Trades Generally throughout the United States and Canada, vol. 45, July 1879 (New York, NY: Dun, Barlow & Company1879), “New York City,” no page number. In 1878, Bradstreet’s Commercial Reports embracing the Bankers Merchants Manufacturers and Others in the United States and the Dominion of Canada, vol. 43, October 1878, “New York City,” p. 93, gave K&E a “C” rating for “good credit, and placed its value between $20,000 and $35,000 ($451,000 to $789,000 in 2010).
 Industrial Directory of New Jersey, compiled by Winton C. Garrison (Trenton, NJ: Bureau of Statistics of New Jersey, 1906), p. 164.
 “$100,000 Fire in Hoboken,” New York Times, December 9, 1905, p. 1; “Opening of Keuffel & Esser’ Co.’s New Factory,” Machinery, August 1, 1907, p. 718. The new factory incorporated many new building innovations, particularly regarding the use of reinforced concrete, and it was “fireproof.” “Partners in Creating the First Century of K&E, 1867-1967,” p. 16, notes the size of the new factory.
 “Keuffel, William G., bookkeeper, 510 Hudson,” Boyd’s Jersey City and Hoboken Directory 1896-1897, pt. 2 H-R, p. 347; “Otto Esser, artists materials, 512 Hudson,” Boyd’s Jersey City and Hoboken Directory 1896-1897, pt. 1 A-L, p. 227. In Boyd’s Jersey City and Hoboken Directory 1897-1898, pt. 1 A-G, p. 28, Otto Esser is listed as a salesman, while later directories list him as a clerk at K&E. “Keuffel, William L.E., supt, 236 Garden, Keuffel and Esser, drawing materials, 117 Adams,” Gopsill’s Jersey City and Hoboken, West Hoboken, Union Hill, Weehawken Directory 1886-1887, pt. 2 H-R, p. 360; “Willie L.E. Keuffel,” New York Times, May 6, 1952, p. 29, notes that Keuffel joined K&E in 1884 and retired in 1945 after being in charge of manufacturing for many years. “C. Bernegau Dies; Aided Army, Navy,” New York Times, September 7, 1948, p. 25; “Willy G. Keuffel, Maker of Drafting Equipment Was With Firm Since Boyhood,” New York Times, May 18, 1942, p. 15; Ottilie Keuffel Busch and Eugen Busch’s son Alfred Eugene Busch also joined the firm in the late 1930s, eventually becoming president in the 1960s, “Partners in Creating the First Century of K&E, 1867-1967,” Keuffel & Esser anniversary booklet (New York, NY: Keuffel & Esser, 1967), p. 15.
 “Engineers Predict Domed City in 2067,” New York Times, April 24, 1967, p. 47; “Slide Rule Going the Way of Abacus as Pocket Calculator Moves In,” New York Times, October 10, 1977, p. 31; “Technology’s Martyrs: The Slide Rule,” New York Times, January 3, 1982, p. F17.
 “Mohawk Data Holding Talks on Acquisition,” Wall Street Journal, August 10, 1977, p. 4, notes that chairman Alfred E. Busch owned 12%, vice president William G. Keller and Robert K. Keller, Karl Keller’s sons, 15% each, and Anita M. Prantner, 13 percent. But other family members owned another 15 percent, because when K&E was sold, the percentage of stock that changed hands was 70 percent. “Keuffel & Esser Co. Holders End Talks With Mohawk Data,” Wall Street Journal, September 9, 1977, p. 13. “Market Place: Merritt Charts Unusual Course,” New York Times, March 1, 1967, p. 56; “Kratos Inc. Signs Accord to Acquire Keuffel-Esser Stake,” Wall Street Journal, December 21, 1981, p. 17; “Kratos Chief Quits; Bank Relief Sought,” San Diego Tribune, December 23, 1983, p. D-11; “Sehnert Leaves Kratos Post,” San Diego Tribune, January 26, 1984, p. F-1, notes that Kratos had borrowed $75 million to buy K&E for $55 million in cash; “Auditors Question if Kratos Can Survive,” San Diego Tribune, April 2, 1984, p. A-13; “Kratos Inc. Loses OTC Stock Listing,”San Diego Tribune, July 3, 1984, p. E-1, notes that Kratos had stopped making interest and principle payments on $72.1 million in debt; “Last Three Years Tough for Kratos,” Cedar Rapids Gazette, July 15, 1984, p. 9B.
 “MIT Museum Receives Landmark Donation of Keuffel & Esser Slide Rule Collection,” press release, MIT Museum, January 15, 2005 (accessed on August 21, 2012).
 “Hoboken,” New York Herald-Tribune, November 19, 1895, p. 8.
 Stegler was born in Hanover. See “Stegler Admits Passport Fraud in Accusing Aids,” New York Tribune, March 17, 1915, p. 3. Willie E. Keuffel is quoted as saying that Stegler worked for K&E for two years in the exporting department, “Charles Boy-Ed Sent Lody to Die,” New York Times, February 26, 1915, p. 1; “Passport Plotters Are Sent to Island,” New York Times, March 20, 1915, p. 8.
 “Cheered for Kaiser, Locked Up,” New York Times, July 9, 1917, p. 2.
 Ziegler-McPherson, Immigrants in Hoboken, p. 38, Table 5, “Hoboken’s German Population, 1880-1930”; Rudolph J. Vecoli, The People of New Jersey (Princeton, NJ: D. Van Nostrand Co., 1965), p. 88.
 Ziegler-McPherson, Immigrants in Hoboken, p. 38, Table 5, “Hoboken’s German Population, 1880-1930.”
 Robert Greenhalgh Albion, The Rise of New York Port, 1815-1860 (New York, NY: Charles Scribner's Sons, 1939, p. 71; Van Winkle, History of Municipalities of Hudson County, 1630-1923, vol. 1, Historical-Biographical, pp. 304-10.
 Hermann Esser, March 26, 1902, U.S. Passport Applications, 1795-1925, National Archives and Records Administration (NARA), Washington D.C., Passport Applications, 1795-1905: ARC Identifier 566612/MLR Number A1 508, NARA Series: M1372; Roll #: 594, located at Ancestry.com on July 12, 2012.
 “William Keuffel Buried To-Day,” Jersey Journal, October 3, 1908, p. 6. Keuffel’s death was also noted in German industrial circles; please see the front-page obituary in The Technologist, Mitteilungen des Deutsch-Amerikanischen Techniker Verbandes, October 1908 (vol. XIII, no. 10), pp. 149-51 (in German). The Technologist obituary notes that Rev. Alexander Richter of St. Matthew’s Lutheran Church was among the speakers at Keuffel’s funeral, so although the service was held at the Deutscher Club there was possibly a religious aspect as well.
 “Esser, Hermann, math insts, h Newark n Passaic av, HC,” Gopsill’s Jersey City and Hoboken City Directory, for the year ending April 30, 1871, pt. 1, A-G (Jersey City, NJ: James Gopsill, 1871), p. 178, “Esser, Hermann, drawing materials, h Bowers n Sherman Av,” Gopsill’s Jersey City and Hoboken City Directory, for the year ending April 30, 1874, Pt 1, A-F (Jersey City, NJ: James Gopsill, 1874), p. 223; Gopsill’s Jersey City and Hoboken City Directory, for the year ending April 30, 1876, pt 1, A-G (Jersey City, NJ: James Gopsill, 1876), p. 176. St. Matthew’s German Lutheran Church, where Hermann and Bertha Esser were married, built a new church at 57 Eighth Street, across the street from the Essers’ home, in 1878.
 “Esser, Herman, drawing matl, 71 Nassau, h 113 Garden, Hoboken,” p. 332, and “Keuffel, William, drawing matl, 71 Nassau, h 113 Garden, Hoboken,” and “Keuffel and Esser, drawing matl, 71 Nassau,” p. 586, Trow’s New York Directory 1868-1869, vol. 1, A-Kup. In 1870, the partners’ home addresses are listed as simply “NJ,” Trow’s New York Directory, 1869-1870, vol. 1, compiled by H. Wilson, Vol. LXXXIII, for the year ending May 1, 1870 (New York, NY: John F. Trow, 1870), p. 336 for Esser, p. 596 for Keuffel.
 “Esser, Herman, instrument maker, h 24 Tenth St, Hoboken,” Gopsill’s Jersey City and Hoboken City Directory, for the year ending April 30, 1878, pt. 1, A-G (Jersey City, NJ: James Gopsill, 1878), p. 223; “Keuffel, William, h 56 Tenth St, Hoboken, and Keuffel and Esser (William Keuffel and Herman Esser) drawing utensils, Grand c Third,” Gopsill’s Jersey City and Hoboken City Directory, for the year ending April 30, 1878, pt. 2, H-N (Jersey City, NJ: James Gopsill, 1878), p. 405; “Esser, Herman (Keuffel and Esser), h 31 Tenth St,” Gopsill’s Jersey City and Hoboken City Directory, for the year ending April 30, 1879, pt. 1, A-G (Jersey City, NJ: James Gopsill, 1879), p. 220; “Keuffel, Wm D (Keuffel and Esser), h 24 Tenth St,” Keuffel and Esser, drawing materials, Third c Grand,” Gopsill’s Jersey City and Hoboken City Directory, for the year ending April 30, 1879, pt. 2, H-R (Jersey City, NJ: James Gopsill, 1879), p. 398; “Keuffel, William (Keuffel and Esser), 188 Hudson St,” Gopsill’s Jersey City and Hoboken Directory for the year ending April 30, 1882, pt. 2, H-R (Jersey City, NJ: James Gopsill, 1882), p. 19; the Essers moved to 190 Hudson Street in 1886, Gopsill’s Jersey City, Hoboken, Union Hill, West Hoboken Directory, 1886-1887, p.1, A-G (Jersey City, NJ: James Gopsill, 1886), p. 205. The Keuffels moved to 510 Hudson in 1892, Gopsill’s Jersey City, Hoboken, West Hoboken, Union Hill, Weehawken Directory, 1892-1893, pt. 2, H-Q (Jersey City, NJ: James Gopsill, 1892), p. 357, and the Essers moved to 512 Hudson Street in 1896, Gopsill’s Jersey City, Hoboken Directory, 1894-1895, pt. 1, A-G (Jersey City, NJ: James Gopsill, 1892), p. 244.
 Ziegler-McPherson, Immigrants in Hoboken, pp. 94-96.
 Ziegler-McPherson, Immigrants in Hoboken, chapter 2, “Little Bremen,” pp. 36-54, p. 78.
 Charles B. Brush, “Title and Early History,” City of Hoboken, Chapter XXXVII, William H. Shaw, History of Essex and Hudson Counties, New Jersey, vol. 2 (Philadelphia, PA: Everts & Peck, 1884), p. 1220.
 Brush, “Title and Early History,” City of Hoboken, p. 1220; Carl Wittke, Refugees of Revolution: The German Forty-Eighters in America (Philadelphia, PA: University of Pennsylvania Press, 1952), p. 334.
 At this point, the Keuffels lived at 512 Hudson Street; Obituary, Wilhelm J.D. Keuffel, The American Stationer, vol. LXIV, no. 15 (New York, NY and Chicago, IL, October 10, 1908), p. 6; Obituary, Keuffel, New York Times, October 3, 1908, p. 9; “William Keuffel Buried To-Day,” Jersey Journal, October 3, 1908, p. 6; Brush, “Title and Early History,” City of Hoboken, p. 1220, notes Esser’s membership on the Board of Trustees.
 Wittke, Refugees of Revolution, pp. 306-07.
 Von Skal, A History of German immigration in the United States, “William Keuffel,” p. 149; Obituary, Wilhelm J.D. Keuffel, The American Stationer, October 10, 1908, p. 6.
 This is an assumption based on the fact that Hermann and Bertha Esser were married at St. Matthew’s, St. Matthew’s Trinity Lutheran Church, Record Book 1, 1856-1875, Marriages: February 22, 1857-March 11, 1874, p. 354, “1869,” entry 322.
 Margarethe Bertha Keuffel, August 28, 1903, National Archives and Records Administration (NARA); Washington D.C.; Passport Applications, 1795-1905; Collection Number: ARC Identifier 566612/MLR Number A1 508; NARA Series: M1372; roll: #635 noted her religion as “Protestant (Lutheran)”. St. Matthew’s moved to 57 Eighth Street in 1878 and St. John’s was founded at 300 Bloomfield Street, Hoboken, in 1889.
 “New York City,” American Druggist and Pharmaceutical Record, June 10, 1895 (vol. 26, no. 11), p. 352, noted that Elka Park “is looming up this summer as a favorite resort of German druggists.”
 “The Elka Club, About Us,” (accessed on August 21, 2012). See also the New York State Office of Parks, Recreation, and Historic Preservation, Elka Park National Registry of Historic Places application, # 1024-0018, Nancy Todd, February 1993. Von Skal, A History of German immigration in the United States, “William Keuffel,” p. 149, says that Keuffel was an honorary president of the Elka Park Association. “Catskills Ready for Visitors,” New York Times, June 16, 1895, p. 12, says that: “Herman Esser of New-York has the distinction of having erected the largest and costliest cottage on the park grounds.”
 Von Skal, A History of German immigration in the United States, “William Keuffel,” p. 149; Obituary, Wilhelm J.D. Keuffel, The American Stationer, October 10, 1908, p. 6.
 Otto Esser lived in Berlin from 1886 to1891, and probably worked at the K&E office there, please see Otto Esser, March 19, 1891, National Archives and Records Administration (NARA); Washington D.C.; Emergency Passport Applications (Issued Abroad), 1877-1907; Collection Number: ARC Identifier 1187503/MLR Number A1 515; NARA Series: M1834; Roll #: 34; Volume #: 60. He traveled to and from Europe at least four times between 1877 and 1895 (the first two trips were as a child with his parents and sister Klara), please see New York Passenger Lists, October 27, 1877, ship Suevia, Year: 1877; Arrival: New York, United States; Microfilm Serial: M237; Microfilm Roll: 410; Line: 16; List Number: 1024; November 1, 1883, ship Gellert, Year: 1883; Arrival: New York, United States; Microfilm Serial: M237; Microfilm Roll: 471; Line: 3; List Number: 1389; November 26, 1892, ship Lahn, Year: 1892; Arrival;, Microfilm Serial: M237; Microfilm Roll: 600,;Line: 19; Page Number: 2; May 11, 1895, ship Palatia, Year: 1895; Arrival; Microfilm Serial: M237; Microfilm Roll: 640; Line: 7; Page Number: 14. Klara Esser traveled to Germany in 1896, please see New York Passenger Lists, June 5, 1896, ship Normannia, Year: 1896; Arrival; Microfilm Serial: M237; Microfilm Roll: 660; Line: 9.
 Carl Bernegau (misspelled “Bergenan”), June 18, 1900, National Archives and Records Administration (NARA); Washington D.C.; Passport Applications, 1795-1905; Collection Number: ARC Identifier 566612/MLR Number: A1 508; NARA Series: M1372; Roll #: 557; Eugen Busch, New York Passenger Lists, September 23, 1938, ship Hansa, Year: 1938; Arrival: New York, United States; Microfilm Serial: T715; Microfilm Roll: 6222; Line: 15; Page Number: 8; Karl Keller, May 17, 1916, U.S. Passport Applications, 1795-1925, National Archives and Records Administration (NARA); Washington D.C.; Passport Applications, January 2, 1906 – March 31, 1925; Collection Number: ARC Identifier 583830/MLR Number: A1 534; NARA Series: M1490; Roll #: 306; Fourteenth Census of the United States, Year: 1920; Census Place: Hoboken Ward 2; Hudson, New Jersey; Roll T625_1042; Page: 16A; Enumeration District: 71; Image: 121, located at Ancestry.com on February 11, 2013.
 “C. Bernegau Dies; Aided Army, Navy,” New York Times, September 7, 1948, p. 25. Louise Bernegau traveled to Germany twenty times between 1909 and1956, the majority of the trips were taken in the 1920s, 1930s, and 1950s, see New York Passenger Lists for Louise A. Bernegau.
 Bertha Keuffel, April 26, 1905, National Archives and Records Administration (NARA); Washington D.C.; Emergency Passport Applications (Issued Abroad), 1877-1907; Collection Number: ARC Identifier 1187503/MLR Number A1 515; NARA Series: M1834; Roll #: 42; Volume #78; March 17, 1910, National Archives and Records Administration (NARA); Washington D.C.; Passport Applications, January 2, 1906 – March 31, 1925; Collection Number: ARC Identifier 583830/MLR Number A1 534; NARA Series: M1490; Roll #103; November 28, 1910, ship Kaiserin Auguste Victoria, Year: 1910; Arrival; Microfilm Serial: T715; Microfilm Roll: 1601; Line: 22; Page Number: 24; February 24, 1911, National Archives and Records Administration (NARA); Washington D.C.; Passport Applications, January 2, 1906 – March 31, 1925; Collection Number: ARC Identifier 583830/MLR Number: A1 534; NARA Series: M1490; Roll #: 128; August 30, 1918, National Archives and Records Administration (NARA); Washington D.C.; Emergency Passport Applications, Argentina thru Venezuela, 1906-1925; Collection Number: ARC Identifier 1244183/MLR Number A1 544; Box #: 4521; Volume #: 2; February 8, 1924, National Archives and Records Administration (NARA); Washington D.C.; Passport Applications, January 2, 1906 – March 31, 1925; Collection Number: ARC Identifier 583830/MLR Number: A1 534; NARA Series: M1490; Roll #: 2425; New York Passenger Lists, December 7, 1889, ship Saale, Year: 1889, Arrival: New York, United States; Microfilm Serial: M237; Microfilm Roll: 542; Line: 9; List Number: 1651A; October 18, 1911, ship Friedrich Der Grosse, Year: 1911; Arrival; Microfilm Serial: T715; Microfilm Roll: 1758; Line: 23; Page Number: 4; December 11, 1929, ship Reliance, Year: 1929; Arrival; Microfilm Serial: T715; Microfilm Roll: 4643; Line 11; Page Number: 12; March 12, 1930, ship Veendam, Year: 1930; Arrival; Microfilm Serial: T715; Microfilm Roll: 4693; Line: 30; Page Number: 19; April 14, 1933, ship New York, Year: 1933; Arrival; Microfilm Serial: T715; Microfilm Roll: 5317; Line: 10; Page Number: 11; November 8, 1935, ship Europa, Year: 1935; Arrival: New York, United States; Microfilm Serial: T715; Microfilm Roll: 5730; Line: 7; Page Number: 19, located at Ancestry.com on February 5, 2013.
 Ottilie and Eugen Busch’s son Alfred Eugene was born in Riga in 1914 but grew up in Königsburg; he came to the U.S. in the mid-1930s to attend college at MIT, “Busch, Alfred E.,” obituary, New York Times, December 10, 2006, p. 54. In 1905, Ottilie sailed from Bremen to New York with a five-month old son Wilhelm(?) and a maid and listed her most recent residence as Riga, New York Passenger Lists, December 1, 1905, ship Friedrich Der Grosse, Year: 1905; Arrival; Microfilm Serial: T715; Microfilm Roll: 646; Line: 8; Page Number: 2. The Buschs lived in Königsburg in the 1920s, New York Passenger Lists, March 8, 1927, ship Deutschland, Year: 1927; Arrival; Microfilm Serial: T715; Microfilm Roll: 4016; Line: 26; Page Number: 141. According to the 1940 U.S. Census, Ottilie, Eugen and Alfred Busch were living at 12 E 86th Street, New York City; in 1935, Ottilie and Eugen lived in Merano, Italy, Year: 1940; Census Place: New York, New York, New York; Roll: T627_2655; Page: 5B, Enumeration District: 31-1333. Ottilie returned to the U.S. from Italy in 1937 with her 29-year old daughter Hildegard, who had been born in Riga (New York Passenger Lists, April 17, 1937, ship Hansa, Year: 1937; Arrival: New York, United States; Microfilm Serial: T715; Microfilm Roll: 5965; Line:7; Page Number: 6), but she must have returned to Italy soon thereafter because she also traveled with her husband back to New York in 1938, New York Passenger Lists, September 23, 1938, ship Hansa, Year: 1938; Arrival: New York, United States; Microfilm Serial: T715; Microfilm Roll: 6222; Line: 15; Page Number: 8. Eugen Busch’s occupation is listed as “manufact” (manufacturer) so he possibly worked for K&E in Europe. John Hiden, The Baltic States and Weimar Ostpolitik (Cambridge, U.K: Cambridge University Press, 2002), p. 45, identifies Eugen Busch as a “prominent German industrialist” and as a member of the Baltic German community in the immediate post-World War I period. Eugen and Ottilie Busch lived in Italy as late as 1940. Eugen remained a German citizen but Ottilie was naturalized in Hoboken on June 20, 1939, New York Passenger Lists, January 12, 1940, ship Rex, Year: 1940; Arrival; Microfilm Serial: T715; Microfilm Roll: 6434; Line: 23; Page Number: 99. Merano is in the Italian Alps, near the Austrian border.
 “C. Bernegau Dies; Aided Army, Navy,” New York Times, September 7, 1948, p. 25; “Stevens to Honor Four,” New York Times, June 10, 1958, p. 41; “Rickover Cautions Class of Engineers on Dwindling Fuel,” New York Times, June 15, 1958, p. 76.
 Pictures of Wilhelm J.D. Keuffel’s sketches and notes are reproduced in “Partners in Creating the First Century of K&E, 1867-1967,” p.13. Among other things, they show that he wrote in English.
 “For Curator, Slide Rules Are Cutting Edge,” Boston Globe, May 10, 2005, p. C-2; “MIT Museum Receives Landmark Donation of Keuffel & Esser Slide Rule Collection,” press release, MIT Museum, January 15, 2005; Smithsonian NMAH, Physical Sciences Collection, Surveying & Geodesy, (accessed on August 25, 2012); Peary-MacMillan Arctic Museum, Bowdoin College (accessed on August 25, 2012).