This non-commercial website was a novel 60th birthday present from Ros. But the site name is thanks to another family member - our daughter Siân. When asked as a teenager what I did, she often told her friends: “My Dad? Oh, he collects expensive sticks of wood!”

When the latest PC/tablet is out-of-date in 6 months it may come as a surprise that the Englishman in the image, the Rev. William Oughtred (1575-1660), invented a calculator around 1621 that would be in continual daily use for nigh on the next 400 years. My hobby is collecting and writing about this analogue calculating wonder - the SLIDE RULE. The analogue concept behind the slide rule was successfully adopted and adapted by many trades and professions. Being able to use one is still a licensing condition private and commercial pilots have to meet.

This site is a virtual “display cabinet” for my collection (as it gets uploaded) of slide rules and the odd mechanical calculating aid plus a “bookshelf” for my published articles - enjoy browsing.

To learn more about the history of this calculating wonder check out the “Slide Rule History” by the Oughtred Society (OS) or my 2-page summary (in Dutch!).

Anyone needing a “memory jogger” or is just intrigued how such analogue calculators of the past worked, the International Slide Rule Museum has a richly illustrated “How To Use The Slide Rule” teach yourself course or download a self-running introduction course with synchronised audio I digitalised. Afterwards try out some test calculations with Derek Ross’ online simulation of a Pickett N909-ES slide rule. If all this gets you thinking about starting your own collection then the UKSRC/OS “Beginner’s Guide to Collecting Slide Rules” can be a great help.

For any educators looking for maths related inspiration & teaching aids/material then you need to look no further than Nicola Marras’ website. But if you are just looking for reference books/publications on slide rules try one of these: List 1 or List 2.