Principles for Sustainable Tech (2007)

When I sat down to start work on the three narratives of the deindustrial future that featured on The Archdruid Report in the last months of 2006, I didn’t know the first thing about slide rules. In the school district I attended, they went out of fashion just before I reached the math classes where they had previously been taught. My only exposure to them was in the form of a 6-foot-long example, a former teaching aid, gathering cobwebs up near the ceiling in a forlorn corner of my junior high school math classroom. Pocket calculators were brand new and fashionable then. Like every other kid at my school, I learned how to make my TI-30 utter the one expletive in its limited vocabulary (punch in 7734 and look at the screen upside down) and blithely forgot about practicing arithmetic.

Curiosity is a powerful force, though, and once the slide rule surfaced as a bit of stage property in my stories, I decided that a calculator that didn’t require batteries or silicon chips might be worth investigating. A few inquiries revealed that most of my older friends still had a slipstick or two gathering dust in a desk drawer. That was how, last Saturday, I found myself being handed a solid aluminum Pickett N903-SE slide rule in mint condition. The Druid who gave it to me is getting on in years and has a short white beard, and though he makes a better double for Saint Nicholas than Alec Guinness, I found myself instantly inside one of the fantasies burned into the neurons of most of my generation:

”This,” Obi-wan Kenobi tells me, “is your father’s slide rule.” I take the gleaming object in one hand, my gaze never leaving his face. “Not so wasteful or energy-intensive as a calculator,” he says then. “An elegant instrument of a more sustainable age.” I press my thumb against the cursor, and...

Well, no, a blazing blue-white trigonometric equation didn’t come buzzing out of the business end, and of course that’s half the point. The slide rule is an extraordinarily simple, low-tech device that lets you crunch numbers at what, at least in pre-computer terms, was a very respectable pace. Even by current standards it’s not slow. I’ve only begun to learn the ways of the Force, so to speak, but after less than a week of practice I can already multiply and divide on my Pickett as fast or faster than I can punch buttons on a calculator.

Beyond its practical uses, however, the slide rule has more than a little to teach about what sustainable technology looks like. It is quite literally pre-industrial technology – the basic principle was worked out in 1622 by Rev. William Oughtred, though it took many years of evolution after that to produce the handy ten-inch device with multiple scales that played so important a role in 19th and 20th century science and engineering. Set a slide rule side by side with an electronic calculator and certain points stand out.

First, a slide rule is durable. By this I don’t simply mean that you have to use more force to break a slide rule than a pocket calculator, though this is generally true. More important is the fact that a pocket calculator has a limited shelf life. Over fairly modest time spans, batteries go dead, memory and processing chips break down, and many plastics depolymerize into useless goo. Even the cheap plastic slide rules once mass-produced for schoolchildren will outlast most pocket calculators, and a good professional model can stay in working order for something close to geological time.

Second, a slide rule is independent. You don’t need to rely on any other technology to make it work or do something useful with the output. Pocket calculators depend on a certain level of battery technology to work, though admittedly this puts them toward the independent end of the spectrum; for a more representative example, think of the number and extent of the technological systems needed to keep a car or an internet terminal functioning and useful.

Third, a slide rule is replicable. If you have one, it doesn’t take advanced industrial technology to make another, or a thousand more; a competent cabinetmaker with hand tools and a good eye can produce them as needed. Making a pocket calculator, by contrast, demands a mastery of dozens of extraordinarily complex and energy-intensive technologies, ranging from clean rooms through solvent chemistry to the manufacture of monomolecular metallic films. Once industrial technology falls below this level, a dead certainty in the deindustrial age, pocket calculators become a nonrenewable resource.

Fourth, a slide rule is transparent. By this I mean that it’s not difficult to work out the principles that make it function from the thing itself. This is crucial, because a transparent technology can communicate much more than its own output.

Imagine for a moment that the deindustrial age turns out much more severe than we have any reason to expect, and nearly all knowledge gets lost. A thousand years from now, a slide rule ends up in the hands of a scholar who knows how to read ancient numbers and can do basic arithmetic. A few minutes of fiddling would show her how the C and D scales can be used to multiply and divide numbers, and a few more would reveal that the A scale shows the squares of corresponding numbers on the D scale. Once she realizes that each scale shows a different mathematical operation, the device itself becomes a Rosetta stone of mathematics that can teach her all about fractions, decimals, squares and square roots, cubes and cube roots, reciprocals, and logarithms, because all the mathematical relationships are right there in plain sight.

If she gets a pocket calculator instead, none of this happens, because the algorithms that make a calculator work are hidden away in its circuitry. Even if the thing still works, it’s a black box that spits out numbers, and the relationships between the numbers would have to be worked out the hard way, by trial and error. Nor is it at all certain that our hypothetical scholar would realize that the calculator was a calculator rather than, say, a remote control or some other enigmatic ancient relic.

SF writer Arthur C. Clarke unknowingly pointed out one of the potential long-term weaknesses of our present technology in his famous Third Law: “Every sufficiently advanced technology is indistinguishable from magic.” What makes a technology more or less advanced is a subtler question than it may appear at first glamce, but Clarke’s point is a valid one nonetheless: once a technology becomes complicated enough that it loses transparency, it can be very hard to recognize the technology for what it is, and very easy to turn it into a stage property for ritual use. (A respectable number of today’s technologies, for that matter, have already become ritual props in industrial society’s mostly unacknowledged ceremonial life; consider the way that computer s are used to justify official economic projections that simply mirror the ideologies and expectations of those who pay for them.)

This has to be avoided if the technologies we pass on to the future are going to be of any use to anyone once the fossil fuels run out and today’s industrial civilization becomes tomorrow’s scrapheap. For that matter, all four of the principles suggested by the humble slide rule – durability, independence, replicability, and transparency – make good criteria for technologies meant to endure into the deindustrial age. Too many of the technologies currently being touted as answers to peak oil fail one or more of these tests, and a good many fail all four. As people in the peak oil community move beyond debating the fact of fossil fuel depletion and start tackling the challenges of planning for a difficult future, a careful study of potential technologies in something like the terms I’ve outlined may be a good place to start.

As a postscript, it might be worth suggesting that since the slide rule itself passes all four tests, getting it back into circulation among people concerned about the future may be a step worth taking. The Oughtred Society (, a nonprofit group of slide rule historians and collectors, provides a good access point for slide rule information, and its website includes a listing of dealers in case your local Obi-wan surrogate doesn’t have a spare slipstick in his desk drawer.