In 1991, while unpacking a removal box, I came across the long-forgotten slide rule from my schooldays. I was intrigued by its history and soon a tongue-in-cheek idea was born: “What else could a 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
• Drum or cylinder
• 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 logarithmic scales and usually a couple of gauge marks. Most items in my collection fit this definition but the odd novel calculating aid and some hybrids have sneaked in!

For enthusiasts or fledgling collectors/users there is an excellent online Reference Manual by the Oughtred Society covering all the basics and much more. Alternatively try An Easy Introduction to the Slide Rule by Isaac Asimov (yes, the SF writer). For cleaning/restoration tips try Eric Marcotte’s or Tom Dilatush’s webpage.

My speciality is ♫ acoustic ♫ (they exist!) and oversized desktop slide rules. But I am also attracted to any slide rule that incorporates a quirky or innovative scale and any 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 is added but because of the sheer volume involved it will take many months, if not years, before the entire collection is uploaded! So check out the relevant NEWS item on the HOME page to see what was in the latest batch!