...was a Keuffel & Esser log-log-duplex-decitrig slide from the 1940's, with twenty-one white plastic scales bonded to teak and a glass hairline indicator, neatly cozied in a stiff leather case.
My father took his slipstick seriously.
He used it all day long, every day. While tinkering in his basement workshop, or while preparing a speech for the local chapter of the American Association of Mechanical Engineers.
He lived in a world of three significant figures. That was the accuracy of the calculations he performed on his slide rule. It was enough for a life of service to his profession and his community.
Even on his deathbed he was slipping his slipstick, plotting the cycles of medication and pain.
With a slide rule, the structure of thinking is visible and tactile. He liked that. He could see and feel the numbers add, multiply, divide. Today, processing takes place invisibly in a microchip forever sealed away from human inspection.
More is going on here than an advance in technology. The change from slide rules to electronic calculators was different, say, than the change from oil lamps to electric bulbs, or from horses and buggies to automobiles. The passing of the slide rule represented a change in how we understand the world.
It is a change from nuts-and-bolts materialism to digital formalism, from a world imagined as hardware to a world imagined as software. The dance of digits inside a computer's silicon chip is destined to become the 21st century's metaphor for reality.