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 or C/D scales. Most 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). But if you are just looking for cleaning/restoration tips Eric Marcotte’s or Tom Dilatush’s webpages can help.

My collection is made up of items from many makers but the niche parts are the ♫ acoustic ♫ (yes, they exist!) and the oversized desktop slide rules. Nowadays I have a special interest in models from the two only Dutch slide rule makers ALRO and Systeem Matthijssen alongside slide rules with a quirky or novel use - e.g. for ringing Church bells. The collection has grown to 2000+ slide rules, 200+ slide charts, 40+ Ready Reckoners, 15+ slide adders and 30+ mechanical calculators. Do try one of the adjacent search options to find items of interest.

Every month or so a batch of new items is added but because of the sheer volume it will be ages before the entire collection is uploaded! So check regularly for any NEWS item on the HOME page announcing the latest batch!