Slip Slidin' Away -- Once A Symbol Of Technology, Slide Rules Have Become Obsolete

"Dad says that anyone who can't use a slide rule is a cultural illiterate and should not be allowed to vote. Mine is a beauty - a K&E 20-inch Log-log Duplex Decitrig."

- "Have Space Suit - Will Travel," 1958, Robert A. Heinlein

Robert Otnes was a high-school senior in 1949 when he and his mother went to the University of Nebraska bookstore in Lincoln to make an important decision: which slide rule he would get for his high-school graduation gift.

After a long and serious discussion with the bookstore clerk, he settled on a Kueffel & Esser Log-log Duplex Decitrig, the same model as the hero in Robert A. Heinlein's science-fiction novel.

It cost about $30. Worth about $200 in today's dollars, it wasn't a trivial purchase.

At the time, slide-rule companies encouraged would-be engineers to purchase the best slide rule they could afford, one that would last through college and into their professional careers.

"This was a big decision. You bought one, and it lasted a lifetime," Otnes said. "It was more of a standard tool, like it was part of your tool chest."

One part of that expectation held true. Otnes, now a consulting engineer from Palo Alto, Calif., still has his Log-log Duplex Decitrig. But it hasn't been a practical tool for more than 20 years. When electronic pocket calculators hit the market in the early 1970s, slide rules slipped from valued instrument to obsolete artifact almost overnight.

The slide rule's doom was jarring because of both its speed and unexpectedness.

They had been around for more than 300 years, were universally used, and were strongly identified with science, engineering and technological progress. Slide rules had helped create the space age. Who would've thought they could become as irrelevant as buggy whips?

Their demise should be a lesson for anyone who assumes that today's high-tech devices - even entire industries - are safe from almost instant obsolescence.

"Everyone woke up one day, and suddenly it had happened," said Craig Finseth, a senior network designer for the state of Minnesota, of the slide rule's passing.

English mathematician and minister William Oughtred is credited with inventing the first slide rule in about 1621, employing the principals of logarithms discovered by Scottish mathematician John Napier.

Used by everyone from tax collectors to carpenters to Sir Isaac Newton, the slide rule became "the world's single most important mechanical aid available to calculate multiplication, division, and square and cubical expansions," according to the "Historical Dictionary of Data Processing Technology."

By the 20th century, they were especially identified as the engineer's constant companion. In college campuses around the world, engineering students could be recognized by the slide rules they carried in leather cases strapped to their belts.

Symbol of technology

In the 1950s and 1960s, those crew-cut engineers and their slipsticks were credited with giving us Teflon, Tang and color television.

No wonder that slide rules became "a symbol of advancing technology of the 20th century," according to Michael Williams, computer science professor at the University of Calgary and author of "A History of Computing Technology."

In Heinlein's vision of the future, for example, humans had built space stations on the moon but were still using slide rules.

A cover of an Astounding science-fiction magazine from the late 1950s depicted space pirates climbing aboard a rocket ship clutching between their teeth not daggers but slide rules.

"It was kind of a magic wand," Otnes said.

Dead in 1975

Shuffling and rustling can be heard over the telephone.

"I'm opening my desk right now," says George Trytten at the other end of the line in Decorah, Iowa. "I'm looking into the back of my desk now, and, as a matter of fact, I've got two of them."

Trytten, a professor emeritus of mathematics at Luther College, may not have seen his slide rules in years, but he remembers clearly the reason he put them in the back of the drawer.

In mid-1972, Hewlett-Packard introduced the HP 35, regarded as the first successful scientific pocket calculator.

At the time, Trytten was an associate professor at Luther, making about $15,000 a year. But he was undaunted by the HP 35's $395 price tag.

"I told my wife, `I don't care what it costs. I'm going to get one,' " he said.

He was the first in his department to buy a pocket calculator. He wouldn't be alone for long. The calculator was so much faster, more accurate and easier to use than the slide rule. And its price rapidly dropped.

"It was like an epiphany for me," he said. "I was actually thrilled with that sucker, I tell you."

Slide-rule companies weren't caught totally unaware. Some tried to get into calculator production. One company produced a hybrid: a slide rule with a four-function digital calculator attached.

"Basically the slide rule was dead by 1975," Otnes said.

A relatively ordinary slide rule recently brought $24,150 at auction at Sotheby's because it was owned by Sergei Korolev, an early leader of the Soviet Union's space program.

Although they are now literally museum pieces, slide rules still have a few things to teach us.

Slide-rule companies that were surprised by the calculator thought their competition was other slide-rule companies, said Russell Roberts, director of the Management Center at the Washington University School of Business. They didn't expect to be wiped out by a whole different industry.

"The real lesson is the competitive marketplace is very broad," Roberts said.