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

Slide rules come in all 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)

They are hard wearing, do not break when dropped and unlike modern day calculators, they do not need batteries! Strictly speaking to be a slide rule it must have at least a pair of Log X scales. Most of the  items in my collection fit this definition but various slide charts, the odd novel calculating aid and some hybrids have sneaked in!

For enthusiasts or fledgling collectors the excellent online 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). If you are just looking for cleaning/restoration tips Eric Marcotte’s or Tom Dilatush’s webpages can help.

The niche part of my collection is ♫ acoustic ♫ ( yes, they exist!) and oversized desktop slide rules. Nowadays I also specialise in slide rules from Dutch makers ALRO and Systeem Matthijssen or any model with a quirky scale for a novel application - e.g. for Church bells. My collection has grown to 2000+ slide rules, 100+ slide charts, 40+ Ready Reckoners, 15+ slide or dial adders and 30-odd mechanical calculating machines/aids. To find specific items of possible interest try one of the adjacent search options.

Every month or so a new batch of items is added but because of the sheer volume it will take many months, if not years, before the entire collection is uploaded! So check regularly and look out for NEWS items on the HOME page announcing details of the latest batch that has gone up!