In 1991, when unpacking a removal box, I came across the long-forgotten slide rule from my student days. I was intrigued - when did they become obsolete? Soon after a bizarre tongue-in-cheek idea struck me: “What else could an (ex)computer man collect but analogue slide rules!”

Slide rules do not wear out or break when dropped and unlike modern-day calculators, they do not need batteries! True slide rules have a pair of Log x (C/D) scales and they come in many shapes and sizes but most are either:

• Linear - by far the most common
• Circular or disc form
• Drum or cylinder form
• Tubular
• Watch (pocket or wristwatch)

Most items in my collection fit this definition but various slide charts, the odd novel calculating aid and some hybrids have sneaked in. For fledgling or existing collectors the Reference Manual by the Oughtred Society covers all the basics and much more. Or else try An Easy Introduction to the Slide Rule by Isaac Asimov (yes, the SF writer). But if you just need cleaning/restoration tips Eric Marcotte’s or Tom Dilatush’s webpages can help.

My collection includes items from many makers. The niche sections are my ♫ acoustic ♫ (yes, they exist!) and my oversized desktop slide rules or ones with a quirky use - e.g. for Church bells. . Nowadays I also specialise in models from the only two Dutch slide rule makers: ALRO and Systeem Matthijssen. The collection has grown to 2000+ slide rules, 200+ slide charts, 40+ Ready Reckoners, 15+ slide adders and 30+ mechanical calculators. Every month or so I add a new batch of items but it will be ages before the entire collection is uploaded! 

Do try one of the adjacent search options or the browse all function to find items of interest.