Walter Shawlee, the sovereign of slide rules, has died at the age of 73

For about 350 years, humanity's most innovative handheld computer was a slide rule. Just as typewriters once symbolized the writer, slide rules symbolized the engineer.

These analog calculators were available in metal, wood, plastic and even bamboo, and could be found all over the world. Their functions include calculating higher order multiplications, exponents and logarithms, among other mathematical operations. They were usually long and rectangular with an extendable center segment, and they had solid fields of stacked letters, lines, and numbers.

They looked almost comically dark, as if they could be used as paddles in the hazing rituals of a math fraternity.

Non-geeks had trouble understanding them. Then, in the early 1970s, lightweight electronic calculators became widely available. The market for slide rules collapsed and production of new devices effectively stopped.

One day, about twenty years later, Walter Shawlee, a middle-aged aeronautical engineer, was looking through a drawer in his home in Kelowna, a mid-sized city in British Columbia, when he happened upon his old slide rule from high school.

It was a Keuffel & Esser pocket Deci-Lon, model 68-1130, with a slim Ivorite body and a delicate, clear cursor box. Both had stood the test of time. Mr. Shawlee recalled saving money for six months as a teenager to buy it.

Inspired by this encounter with his youth, he created a website dedicated to slide rules. It didn't take long for nostalgic math whizzes from decades past to come across the site. Emails flooded Mr. Shawlee's inbox. He began spending eight hours a day researching, buying, repairing and reselling old slide rules.

“Are you trying to corner the slide rule market?” his wife Susan Shawlee nervously asked him to The Wall Street Journal reported in 2003.

The Institute of Electrical and Electronics Engineers' journal, Spectrum, found in 2007 that Mr Shawlee had effectively 'cornered the global market'.

“He's Mr. Slide Rule,” a Texas engineer and slide rule enthusiast told The Journal. “Walter knows everyone in the slide rule racket.”

Mr Shawlee died on September 4 last year at his home in Kelowna. He was 73. The death was not widely reported at the time and The New York Times was only informed of it last month. His wife said the cause was cancer.

Mr. Shawlee wasn't just a slide-rule sentimentalist entranced by memories of teenage nerds. He argued that slide rules had an intrinsic appeal for several reasons.

For example, he saw dignity in their strength and design. In a 1999 profile for The Times, Mr. Shawlee described slide rules as “the techno-boy version of a broadsword.” Up website, the Slide Rule Universe, he contrasted them with digital technology. “Fifty years from now, the computer you use to view this web page will be a landfill,” he wrote, “but your trusty slide rule will be broken in just fine!”

For Mr. Shawlee, the lost durability represented by slide rules was part of a broader story of decline. “When we used slide rules every day in the 1960s, we could send people to the moon,” Mr. Shawlee told the Journal. Speaking to The Times, he noted: 'People who grow up with calculators have no understanding of numbers.'

Joe Pasquale, professor of computer science and engineering at the University of California, San Diego, has taught classes on the “history, theory, and practice” of slide rules, including a survey of “the best slide rules ever made,” as he put it in a Course description.

In an email, Professor Pasquale explained the pedagogical value of slide rules. Calculators tend to replace the human mind, requiring users to simply punch in numbers and 'blindly accept' a result, leading to a loss of the user's ability to calculate – 'and more generally, after to think,” wrote Professor Pasquale. While slide rules require active involvement, he added, “expanding the mind's computing power.”

It was Mr. Shawlee's good fortune that a surprising number of people shared these views. In the early 2000s, he made $125,000 a year repairing and reselling slide rules. The company paid for his two children to go to college, and one of them went to law school. His customer base took its most organized form the Oughtred Associationa club named in honor of William Oughtred, the Anglican minister widely credited with inventing the slide rule in the early 1920s.

Mr. Shawlee's Web site developed a subculture of its own, with a network of slide rules from Arizona to Venezuela to Malaysia sifting through the moldy wares of old stationery stores and estate sales and school district warehouses on Mr. Shawlee's behalf. of slide rules. In Singapore, an official, Foo Sheow Ming, visited the back room of a bookstore and found 40 unopened crates containing more than 12,000 slide rules in different varieties. On his website, Mr Shawlee called the find “the absolute El Dorado of slide rules”, and Mr Foo told the Journal it was “the mother lode”.

Because government regulations prohibited making a profit on the goods, Mr. Foo sold the slide rules to Mr. Shawlee at a discount. “It's all about the thrill of the hunt,” he told the Journal.

Including Mr. Shawlee's inventory remarkable artifacts of the history of science. He offered a slide rule made for machine gun operators, with calculations for wind, altitude and range. He offered a slide rule for measuring metabolism, with different settings for age, gender and height. And he used his website to explore hidden points of slide rule-iana, writing about slide rules, for example made by the US government for calculating the effects of nuclear bombs.

“Would you like to know what the optimal explosion height is for that new nuclear bomb you just bought?” Mr. Shawlee asked in a mock sales pitch. “What about the high-confidence lethal zone radius, or the temperature at an exact distance from the nuclear weapon that just went off a block away? These babies can answer all those burning questions when you are flambéed into free ions and radioactive dust at a speed of about 2,100 kilometers per hour.”

He also sold slide rule cufflinks and slide rule tie clips, which in some cases had been made by major slide rule manufacturers as promotional items during what Mr. Shawlee called “the golden age of slide rules.” The tie clips proved so popular in the Slide Rule Universe that Mr. Shawlee partnered with a small foundry to produce them himself.

Over time, his customers included a weather station in Antarctica, where many electronic gadgets couldn't handle the cold; photo editors responsible for adjusting image sizes (they like slide rules for their clear display of different values ​​for the same ratio); an archaeologist who discovered that calculators became too dusty to work properly during excavations; the pharmaceutical company Pfizer, which gave away slide rules at a trade show; slide rule enthusiasts in Afghanistan and French Polynesia; and “NASA guys,” Mr. Shawlee told Engineering Times in 2000.

Walter Shawlee II was born on November 27, 1949 in Los Angeles. His mother, Joan (Fulton) Shawlee, was an actress known for her role as Sweet Sue, the leader of the “girl band” at the center of the film “Some Like It Hot” (1959), and for her role as Pickles Sorrell. a recurring character on “The Dick Van Dyke Show” (1961-66). His father was a hotel concierge and painter who specialized in seascapes.

At the age of 14, Walter worked in an electronics store and devotedly read magazines such as Electronics World. He studied engineering and mathematics at the University of California, Los Angeles before dropping out. He worked several jobs, including as an assembly line welder at a Volvo factory in Sweden, before founding Northern Airborne Technology, a successful aviation communications company, in Kelowna. He sold the company in 1992.

He then became a hired tinkerer and inventor, helping companies design things like machines that could gently apply labels to a variety of fruits. He repaired and sold gadgets, including signal generators, high-voltage rectifiers and cathode ray tubes.

He and his wife first met at UCLA, and they married in 1971. In addition to her, he is survived by their children, Walt III and Rose Shawlee, and a half-sister, Angie Barchet.

When The Journal visited the Shawlee household, about a thousand slide rules were scattered across the dining room table, Mr. Shawlee's home office and the family sauna. “I know my wife wants her dining room back soon,” he told Spectrum magazine.

In a telephone interview, Ms. Shawlee said thousands of devices were still in the family's home. She said she plans to keep selling them. As far as she knows, there is no prospect of another collector-expert-fixer-dealer romance like Mr. Shawlee appearing in “the slide rule racket.”