My Slide Rule Collection

Sorry about the tons of graphics, but the way I see it, if you're interested in slide rules then you're probably an incredible geek (like me) and therefore one of the technological elite with a high-speed connection.

I've been collecting slide rules and other mechanical calculating machines for some years now. I've amassed a collection of around forty, plus twenty or so adding machines and perrygrafs. I am particularly fond of my Grandfather's K&E; 4088-3 slide rule, a Concise 600-ST Science Tables circular slide rule, and a neat little 5" K&E; 4097D glued to the back of an Arithma Addiator. I've also got the Sterling that I bought in college in 1985 ... the very last time I ever saw a slide rule for sale as a calculating instrument and not as an antique.

I don't just collect slide rules - I use them! I use one at work because it annoys the computer department people to no end (they desperately deserve annoying), and I use one in my workshop to calculate sprocket sizes and tool speeds, because mostly it doesn't run down when I leave it on.

I've even designed some of my own slide rules. The first was a "combat calculator" for the game Dungeons & Dragons back in high school. Since then I've made several for navigation, such as one that calculated the course and speed of a target given three azimuth/time observations. Technically, these contraptions are not slide rules as they're not intended for general calculation. They're "perrygrafs", named after an early manufacturer of the type.

One of these days, I hope to write a book on designing slide rules and perrygrafs, as these instruments are still very useful.

Enough blabage. On to the collection...

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© 2003 W. E. Johns