The Comptometer: The Adding-Machine Patent Dorr Felt Won in a Year, While Burroughs Waited Three

By Matthew Partsch · Owl and Twig Vintage · October 2, 2026

William Burroughs filed for his adding machine in January 1885. Dorr Felt filed for his a year and a half later and held an issued patent within twelve months — Burroughs waited three years for his. The company that put its product's name on the federal trademark register first is not the company whose own name became famous enough to need no proof at all, and the gap between the two machines explains why.

What a Comptometer is, and what it isn't

A Comptometer adds numbers the moment its keys go down. Each of its eight or more columns carries keys numbered 1 through 9, arranged in a bank; pressing a key moves that column's register wheel directly, with no crank to turn and no separate step to total the result. Dorr Felt built his first working version from a macaroni box, with skewers, staples and rubber bands standing in for the mechanism, over the Thanksgiving holiday of 1884, finishing it shortly after New Year's Day 1885. That prototype is now in the Smithsonian. A real machine followed once Chicago workshop owner Robert Tarrant agreed to finance it, completed October 5, 1886.

William Burroughs's machine solved the same problem differently. It turned a crank, and — this is the part that mattered to the banks and insurance offices that became its biggest customers — it printed every figure entered onto a paper tape before totaling them. The company's own early product name, the Burroughs Registering Accountant, says what it was built for: a machine that produced a checkable record alongside its total. A Comptometer, run by an operator who made no mistake, was faster. A Burroughs machine, run by anyone, left proof.

That speed came at a cost. Felt & Tarrant ran dedicated operator schools, three weeks to three months long, teaching touch operation — entering a full number with both hands at once, without looking at the keyboard. A December 1970 comparison in the trade publication Management in Action, cited on the specialist site Vintage Calculators, found that entering the number 39,407.05 took five simultaneous keystrokes on a Comptometer against nine separate keystrokes on a ten-key electronic calculator, concluding that the key-driven machine remained the fastest adding machine available even by 1970 — while conceding that an electronic calculator did at least half again as much multiplication and division. That trade-off, speed against training against a paper trail, is the whole reason two very different machines sold alongside each other in American offices for most of a century.

Two patents, filed a year and a half apart

Burroughs filed first. His application, for what the Patent Office eventually titled a "Calculating Machine," went in on January 10, 1885, assigned to the American Arithmometer Company he and three St. Louis partners had organized the following year. It took three and a half years to clear: US Patent 388,116 was granted August 21, 1888, alongside three related patents numbered 388,117 through 388,119, granted the same day. Burroughs did not wait for the patent to put a machine on the market — the company built and sold fifty units in 1887, at $475 each, while the application was still pending. They were difficult enough to run correctly that, according to Smithsonian magazine's account of the company's early years, Burroughs himself was reportedly the only one who could operate them reliably. A redesign through the early 1890s added safeguards against entry errors and improved the printing mechanism, and the company's fortunes turned around from there; general accounts of the adding-machine market date Burroughs's real commercial arrival to around 1892, several years after Felt's machine was already selling.

Felt filed second and got there first. His application, backed by Tarrant's money and a working machine completed in October 1886, went in July 6, 1886 — eighteen months after Burroughs's own filing — and was granted within a year, on July 19, 1887, as US Patent 366,945. A second patent, covering a stop-motion device that kept the register wheels from over-rotating during a carry between columns, followed October 11, 1887 as US Patent 371,496. Felt held an issued, enforceable patent for more than a year before Burroughs held his, despite starting the paperwork a year and a half after Burroughs had already begun it.

Google Patents' own digitized text of Felt's two patents renders his name wrong twice, two different ways: the scan of 366,945 reads the inventor as "Donn E. Felt," and the scan of 371,496 reads him as "Dore E. Felt." Neither matches Dorr. It is the same kind of optical-character-recognition artifact this series has flagged before on other century-old filings — worth naming because a name search against the wrong spelling turns up nothing, not because either error changes who filed the patent.

The companies that outlived their founders

Felt and Tarrant incorporated the Felt & Tarrant Manufacturing Company on January 25, 1889, in Chicago. The partnership itself lasted until 1902, when it split: Felt kept majority control of the manufacturing company, and Tarrant took the Comptograph Company, a related firm built around Felt's earlier printing-adder patent. Felt & Tarrant went public in 1947, renamed itself the Comptometer Corporation in 1957, and merged with the Victor Adding Machine Company in 1961 to form the Victor Comptometer Corporation — a name that survives today, reduced to Victor Technology LLC.

Burroughs did not live to see his own company succeed. He died September 14, 1898, in Citronelle, Alabama, six years after the redesigned machine had started selling reliably. The turnaround belonged to Joseph Boyer, the company's third president, who had worked alongside Burroughs at his bench during the difficult early years. Boyer secretly bought a rival, the Addograph Manufacturing Company, in 1903, then in 1905 moved the entire operation from St. Louis to Detroit and renamed it the Burroughs Adding Machine Company. In 1953 the company renamed itself again, to the Burroughs Corporation, and began building digital computers for banks. It merged with the Sperry Corporation in September 1986 to form Unisys, ending what Wikipedia's own account of the company calls its hundred-year independent history as a business-equipment maker.

One more thread connects the inventor to a name more people recognize today. William Seward Burroughs's son Mortimer Perry Burroughs was the father of William S. Burroughs, the Beat-generation novelist who wrote Naked Lunch. The novelist's father held his inherited shares in the family company longer than his siblings did, and sold them in 1929 — just ahead of the stock market crash — for $276,000, according to Smithsonian magazine's account. The inventor never saw any of it; the machine that outlived him funded two more generations of a very different kind of American reputation.

One trademark filed in 1905, the other in 1968

Felt & Tarrant registered COMPTOMETER as a federal trademark on August 8, 1905 (Registration No. 45,076, filed April 28, 1905), covering "key-operated calculating machines." The application swore a first-use-in-commerce date of September 1, 1888 — meaning the company had been selling machines under that name for seventeen years before it bothered to register it, and eighteen years after Felt's own first patent. The mark lapsed in 1986, when nobody filed the paperwork to renew it under Section 9.

The word BURROUGHS itself is a different story. Searching the modern federal trademark database for every mark Burroughs Corporation has ever owned, the earliest registration for the plain word BURROUGHS turns up with a filing date of January 19, 1968 — for "electronic components—namely circuit modules, magnetic cores, readout devices," reflecting the company's pivot into computing by that point, not adding machines at all. That is eighty years after the 1888 patent grant and sixty-three years after Joseph Boyer put the Burroughs name on the company in 1905. No earlier registration for the word turned up in this search; older, paper-only Patent Office records that predate full-text digitization may not all be indexed in the database used here, so this is reported as an absence found in this research, not as proof that no earlier registration ever existed anywhere.

How to date a real one

Both machines can be dated closely from the case and the markings alone, using the model and serial-number references compiled by calculator historian Jaap Scherphuis.

Maker & model	Case, keys and markings	Approx. years
Comptometer, wooden case	Wood case, flat metal plate over the register; nameplate reads "Felt & Tarrant Mfg. Co., Chicago"; serials 10–6244	1887–1903
Comptometer Model A	Copper-plated steel case painted brown (often stripped shiny today); serials 15000–20603	1904–1906
Comptometer Models F–J	Black-and-white keys (F, H), then green-and-white (J); "Comptometer" name appears on the case panel from Model H on; Model J serials run roughly J245489–J346384	c. 1911–1938
Comptometer Models K, M, 992	Nameplate reads "Comptometer Corporation" after 1957, "Victor Comptometer Corporation" after 1961; Model 992 serials 5014–42739	1934–1961 and later
Burroughs Class 1, "Registering Accountant"	Large listing machine on a metal stand, glass panel over the printing mechanism	1880s–1930s
Burroughs "Shoebox" (Class 5)	Black case styled like a contemporary Comptometer, but with one more key column	1911–1914
Burroughs "Leggy"	Rounded black case, green keyboard plate, small metal legs with tiltable rear extensions	1915–1936
"Baby Burroughs"	Smaller 6-digit register, flat base on rubber feet instead of legs; later versions in color	1928–1960s

• Check the case material on a Comptometer first: wood means 1887–1903; metal with a copper-brown finish narrows it to the 1904–1906 Model A.
• Read the nameplate rather than trust a listing title. "Felt & Tarrant Mfg. Co." predates 1957; "Comptometer Corporation" is 1957–1961; "Victor Comptometer Corporation" is 1961 or later.
• On a Burroughs machine, the case style narrows the window fast: a rounded black case on short legs with a green plate is the 1915–1936 "Leggy"; a flat 6-digit model on rubber feet is a "Baby Burroughs," 1928 or later.
• Match the serial number's leading digit against the class number before trusting a seller's stated year — a "5-" prefix is Class 5, an "8-" prefix is Class 8, and so on.
• A legible stamped patent date on a Burroughs machine (surviving examples carry dates into the 1910s) narrows the year further than the serial number alone, when the stamp is still readable.
• Treat any model-based year as a window, not an exact date. Even Scherphuis's own serial-number charts note that actual production commonly ran two to four years behind what the serial number by itself would suggest, on at least one well-documented model.

What they sell for

No publicly verifiable hammer price turned up in the research for this guide, for either machine. The clearest number on record is an estimate, not a result: Auction Team Breker, a German specialist house for mechanical calculators and office machines, offered a lot at its September 16, 2023 sale pairing a documented 1887 Comptometer Model No. 1 (serial no. 3954, mahogany case, described as in very good working condition) with a circa-1920 copper-cased Comptometer and a 1961 Victor Comptometer Corporation share certificate. The pre-sale estimate for the lot was €1,200 to €1,800, against a €600 starting price; the actual hammer price sits behind the auction house's own login wall.

Everything else here is an asking price or a single appraisal estimate, and is labeled as such. A Felt & Tarrant Comptometer from the 1920s sold on eBay for $40 before that listing ended — an asking price, with no confirmation the sale went through at that figure. A Burroughs Model 3, dated by the seller to 1904–1906 with its original crank mechanism, was listed active on eBay at $64.99 with a Best Offer option. A dealer's circa-1910 Burroughs listing on 1stDibs and a sold-out Etsy listing for a portable Burroughs both omitted price entirely. The one formal appraisal found in this research — from an antiques specialist answering a question on JustAnswer, for a working 1908 Burroughs Class 1 machine — put the fair-market resale value at $175 to $250, explicitly as an estimate for auction or online sale, noting a brick-and-mortar antique shop might realize 30 to 50 percent more.

Where the records disagree

Two sources on Burroughs's early years read, at first glance, as if they disagree about when the company succeeded. Smithsonian magazine's account puts the first fifty machines on the market in 1887, sold at $475 each, difficult enough that Burroughs himself was reportedly the only one who could run them correctly. A general history of the adding machine instead dates Burroughs's real commercial arrival to around 1892. Read together rather than against each other, both are true: 1887 was an unreliable first run sold before the patent had even cleared, and 1892 is closer to when the redesigned, safeguarded version actually took hold in offices. A single "year Burroughs succeeded" answer depends entirely on which of those two moments a source picks.

The filing date of Felt's second patent is a smaller, unresolved point. Wikipedia's account of the Comptometer gives March 12, 1887 as the filing date for US 371,496; the patent's own digitized text instead references the earlier application number from his first patent, in a way that does not clearly state a separate filing date of its own. This guide follows Wikipedia's date, since it is consistent with the roughly seven-month gap between that filing and the October 11, 1887 grant — in line with how quickly Felt's first patent had already cleared.

The absence of an early Burroughs trademark is reported the same way: as what turned up in this research, not as a settled fact about Patent Office history before full-text search existed. And the serial-number dating tables above carry their own caveat, in the source's own words — at least one Comptometer model's actual production year commonly ran two to four years behind what its serial number alone would suggest, which is reason enough to treat any case-and-serial dating here as a window rather than an exact year.

The cash register is this shop's other guide built around a founder who filed first, a rival who commercialized better, and a trademark that arrived years after the machine itself. For the rest of the library, see the Field Guides index.