By Erin Sherbert
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To those born after 1970, the thought of sending someone into space with a slide rule seems ridiculous, but, to early Apollo crews, the mere thought of going up without one would have been a good enough reason to scrub a launch. Slide rules (the Pickett N600-ES Dual Base Log/Log to be precise) were compulsory equipment during our first five trips to the moon; in fact, Neil Armstrong probably determined the distance between one step for man and a giant leap for mankind by using his trusty pocket-size Pickett. Prior to 1972, no feat of modern engineering was undertaken without a slide rule. The space shuttle, the Golden Gate Bridge, the Hoover Dam, the atomic bomb, the Panama Canal, and the Empire State Building (which, by the way, survived a head-on collision with a 10-ton B-25 bomber in 1945 with nary a tremble) were all conceived and completed using a slide rule, an instrument invented in the early part of the 17th century. During my father's generation, the slide rule was more common than the telephone; students were required to carry them from class to class (the nerdiest wore the rule cases dangling from their belt loops like gun holsters); circular, rectilinear, and triangular rules were made from metal, wood, and plastic, in every size, for every purpose imaginable; custom slide rules could analyze aerial photography, calculate the concentration of hydrogen ions in an alkaline solution, determine the structural integrity of a bridge truss, or gauge the planks of lumber in a tree and cuts of beef in a cow. There seemed no end to what they could accomplish. Then, in 1972 Hewlett-Packardintroduced the HP-35, the world's first scientific handheld calculator, and slide rules disappeared from the public consciousness faster than my science professor could find the cosine of a 15.5-degree angle. Now, no one uses them.
"That's not exactly true," counters Bob Koppany, an optometrist from Southern California. "Most airline pilots still carry a slide rule just in case the GPS craps out."
The aptly named Dead Reckoning Computer is a small circular slide rule that estimates the plane's position using course, speed, and time, as well as fuel requirements for distance traveled. I study the intricate configuration of dashes, signs, and integers arranged around the edges of the tiny wheel, and conclude that trains are very nice indeed.
"This one calculates the effects of a nuclear explosion," says Koppany, picking up a deceptively innocuous-looking slide rule from a pile that threatens to spill over the table onto the floor.
A fellow member of the Bay Area- based Oughtred Societysaunters over to the table and offers Koppany $30 for a mechanical pocket watch/slide rule.
"Hmmmm," ponders Koppany. "Considering I paid $3,000, and there are only 10 to be known in existence, I'd have to say ... no."
The bargain hunter pauses for a moment and then offers $50; they both laugh like old friends and spend a few minutes discussing the exploits of today's biannual Oughtred Society Meeting and Auction. With slide rules going for as little as $5, Koppany has managed to spend several thousand dollars; however, his pile of antediluvian swag is impressive even if this crowd isn't easily impressed.
The Oughtred Society, named after William Oughtred, the English clergyman attributed with inventing the slide rule in 1622, was formed in 1991 in Emeryville by three casual collectors who had been on intimate terms with the slide rule during the early part of their engineering careers; the society's roll call is now several hundred strong and is separate from the International Slide Rule Group, which boasts an online message board with more than 700 registered members. Barring a very few, most society members recall a time when slide rules were an integral part of their lives and snow was not a hair color; most of them have also acquired one or two doctorate degrees in their lifetime, not excluding Rick Blankenhorn, the only professional dealer set up at the convention. In a past life, Blankenhorn was a full-time staff scientist for an aerospace company; now he peddles antique instruments of science. These are his people.
"It's a little irritating that an early Barbie doll can go for $7,000 at auction, but a slide rule of historic importance and superb design goes for one-tenth of that," says Blankenhorn in a voice that suggests more than money is at the root of his concern. "They're disappearing."
Keuffel & Esser, the largest manufacturer of slide rules in the United States, produced its final rule in 1975. Although currently housed in the Smithsonian Institution, it would pale next to 80 percent of the slide rules represented here. There are hundreds spread out on long banquet tables, each lovingly labeled and categorized -- astronomical rules, shipping rules, rules for aligning howitzer guns, rules for measuring alcohol content, rules made of ivory, bamboo, and brass, rules that span centuries and continents, for purposes that have become indecipherable. Like old maps, compasses, and clockworks, old slide rules have an air of mystery and destiny about them; the newer slide rules seem lighthearted and oftentimes foolish, like the happy yellow Pickett pocket model, or the military issue for measuring the effects of a nuclear blast on your location.
"Some of them are just adorable," says Jean Collins, referring to a 4-inch antique she hoped her husband would procure today. Richard Collins, a former aeronautics engineer and test pilot, returns with bad news. Jean chuckles, not taking it too hard. Between them, the Collinses have hundreds of slide rules, as do most society members, but the collection counts as just one of their many hobbies. (The Collins home also accommodates an assortment of antique tools, an airplane, a number of freeloading wild coyotes, and a family of rehabilitated owls that continues to return for treats.)
As the sun begins to weaken, the group migrates to the home of Thomas Wyman, current Oughtred Society president, for dinner and cocktails. Perhaps, if they put their heads together, they'll finally figure out how Conrad Schure's newly acquired German astronomical slide rule functions, or why, for that matter, Pongis making a comeback. In this crowd, there is never a shortage of things to talk about.