The Old Rules

Frederic D. Schwarz’s article about slide rules (“Notes From the Field,” Fall 1993), caught my eye. My comment is that newer is not necessarily better. I teach physics, math, and computer courses, and I keep telling my students that one should first consider the task at hand and the desired results before automatically grabbing for a pocket calculator or a computer. For certain types of calculations, slide rules can still run rings around any electronic instrument. A case in point is working out grade curves for the courses that I teach. For the kind of calculation involved, and given that I need only two- or three-digit accuracy, I can get grade curves much faster and much more efficiently with my old slide rule than with anything electronic. It must be some kind of ultimate irony for me to be using a slide rule to work out grade curves for computer courses.

Edward A. Vondrak
Professor of Physics and Mathematics
University of Indianapolis
Indianapolis, Ind.

The Old Rules

It’s true that slide rules have been almost completely replaced by pocket calculators, but the making of calculators and their batteries requires an enormously complex manufacturing enterprise. Slide rules consist merely of two logarithmic scales sliding against each other. Our world has become more complex rather than simpler.

For some arithmetic chores, such as ratio and proportion, slide rules are easier to use than pocket calculators. When one establishes a ratio on the rule such as 4:3, then all other identical ratios such as 1.4:1.05 and 7.6:5.7 are established without further movement of the slide. One merely reads them off. A friend operates a small factory where he has to continually recalculate mixing ratios involving several components. The batches vary in size, so they involve new numerical values. He takes an old twenty-inch slide rule and makes one setting and then reads off all the proportional values.

John J. Bowen
Orland Park, III.

Out Of The Clouds

I enjoyed very much the article “Lighter Than Air” by Peter Andrews (Summer 1993). In the early thirties I lived near Canton, Ohio, just twenty miles south of Akron, where Akron and Macon were built. Our father frequently took my brothers and me to Akron on Sunday afternoons to view the progress of construction. At the time, I went to a small country school in the middle of farmland. One spring morning when the clouds were hanging very low, we were out in the schoolyard during morning recess when we heard the sound of engines coming from the north. As we turned toward the sound, a huge dirigible came out of the clouds, heading directly toward us. It was Macon on what may have been her first test flight. She was going very slowly, presumably only fast enough to maintain steerageway. And she was so low that as she passed directly over our heads we not only could make out the facial features of the crew members leaning out of the controlcar windows but could—and did- actually talk to them. Given the state of instrumentation at the time, I assume now that the crew had to maintain eye contact with the ground to know their altitude. It was an experience that I have never forgotten, and it left me a fan forever of lighter-thanair ships.

R. H. Harrison
Odessa, Tex.