This site is under development - it may take some time to have it fully up and running. The intention is to introduce you to some of the many types of slide rule and mechanical calculators in common use up until the early 1970s when electronics, the microchip and electronic calculators entered the scene. Nowadays, personal computers, spreadsheets, iPhones and iPads have gained total control over practically every aspect of everyday life.

The slide rule, or guessing stick, as it was sometimes called, has now become virtually extinct. My first slide rule was given to me by my grandfather when I was about 12, I took it to school and my maths teacher showed me how to multiply and divide with it. That small slide rule accompanied me everywhere for nearly 20 years - I still have it. It turned me into an instant mathematical genius - even the more able classroom mathematicians were still only using those little flat pocket adding machines with the holes and the pointed pencil thing (the stylus) that changed the numbers (see Pocket Calculators).

I purchased my last slide rule for serious use in about 1970, it cost the company about £10 if I remember rightly because it was a slightly superior model. I never really used it though, because the electronic calculator became available at a cost of between £40 to £70. Most of those early electronic marvels were only capable of the four basic functions - addition, subtraction, multiplication and division. £40 in the early 70s was more than a weeks wages. Today, 40+ years on, a 90 function electronic pocket calculator - such as most of those in the Casio range will cost less than £10. The upside of the slide rule being that they didn't need batteries. The downside being that you couldn't see to use them in the dark. You would also have needed a set of log tables and a pencil and paper to help you keep track of the decimal places and remember the intermediate results.

I have divided this site into categories - each category section is self-contained - just click on the category of interest from the menu at the top and you will go into the main page for that category - you can go back to the home page any time to select a new category.


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