Wednesday, December 31, 2014

A Slide Rule is Built

If there is no power on the ship, your calculator batteries are dead, and you need to do a thermodynamic calculation to finish repairing the steam turbine, you ought to have a slide rule. Or, a spare calculator. For the last post of the year, I’m diving into the history of how we calculate. At the start of plebe year, midshipmen at KP purchase two calculators for classes- a low-powered, $15, scientific version known as the TI-30, and a TI-84 graphing calculator. Because the TI-84 knows too much, some math tests require that you use the ‘dummy’ scientific calculator. But the $15 handheld device was the thing that put the slide rule out of business. What history the TI-30 has. Launched in 1976 (with LED lamps, less functionalities, and a larger size), it cost $25 in then-dollars, or $103 today. The affordable device opened electronic computing power to a wide audience, and sent slide rules the way of the steam locomotive: at least for the Atari generation. Technology is for the young, and browsing forums, I discovered that, in the 1980’s, experienced slide-rule-toting architects and engineers feared younger professionals who never used the slide rule. (Today, there are still aficionados for hand drawings over digital blueprints, including KP faculty). I got a brief overview on the theory of slide rules from a neighbor in my dormitory. He actually prefers the slide rule, and it got him through high school and into KP. Of course, the slide rule is so quaint that the SAT and ACT don’t mention it on the list of approved calculators. As scientific calculators without power cords, they appear to be permitted. I bet that Mr. Miller brought an electronic calculator just in case the proctor wasn’t in the know. You have to be smart when using the slide rule. You have to count your zeroes, and project a reasonable answer. These are good skills that successful students use. My father has a Pickett Synchroscale model, with leather case, on the shelf at home. With some time on my hands during the winter break, I decided to make one of my own. I printed a template off the internet, and hit the arts-and-crafts store. The store was an intersection of fine arts majors and architects, and I got some interested looks as I built my gizmo. I cut some polystyrene sheets to make a bezel and a slide, and got some clear PVC to make the viewer. I pasted on the template strips, and voila, a slide rule. Perfectly suited for use as a hipster accessory, or as a calculating device. Give some respect to the slide rule: they built America. As for slide rules that still earn their keep, some variants of the slide rule exist for navigational purposes for airline pilots and ship’s mates. These are used to determine distances on scaled drawings. Print a slide rule: How to use a slide rule: List of slide rule makers: Images of the original TI-30:

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