I hated slide rules in school. Looking back now I think it was just a failure to spend a little time coming to grips with them in the first place. In retrospect they make perfect sense. Instead i battled through my HSC Industrial Arts in 1973 with the cumbersome 5 figure log tables, ubiquitous at the time.
When I went into engineering I was so §¥#% chuffed to learn that TAFE required SEVEN figure log tables for better accuracy. Fortunately the electronic calculator came into common use in my first year of employment and training. Suddenly life got considerably easier and you could sail through complex calculations in a breeze and concentrate on your design.
Found this noodling about on gumtree. It’s a simple time distance circular slide rule. Know two variables and it gives the third. I devised a simple variation of these for my guitar students to change music keys. In fact the RTA published one that was a rest break calculator that covered the pacific highway years ago showing stops and rest areas. Not much need for me on Lake Mac to have one but thought I’d throw it up for anyone that is more far ranging on the briney and might might like to make one . This link shows how to use a cd and cd case to do it .
https://www.sliderulemuseum.com/SR_Scales.htm
No batteries required
P.S. just remembered as an afterthought. When I started working some of the designers were still using these mechanical calculators called Brunsvigas. Invented in the 1920s . And you young blokes worry about getting the latest operating system on ya iPhone
Weight was roughly the same as my plough anchor
