### I re-discovered my slide rule a while back, the one I used in school maths lessons, way back when. I didn’t know just how utterly classic such things were, even then.

These things mostly worked because of a quirk of mathematics – the logarithm, which means you can add logs, as a linear measure, to multiply. And there’s more. In the photo, I’ve set my slip-stick to do the pi times table – and believe me, it’ll calculate that to about two decimal places (which is OK for a quick estimate) faster than you can punch the same thing into a calculator. All you have to do is slide the centre piece to the right point and look along the ruler. Cool.

Time was when no self-respecting space adventurer set off without one of these. They were a staple in Robert Heinlein’s sci-fi, among others. With them you could not only defeat the squidgy aliens who were trying to make off with all Earth’s water – you could go on to conquer the entire universe.

And, just to nail how fast the world changes, NASA actually did conquer the Moon with slide rules. Apollo-era engineers carried them the same way we carry phones.

My slide rule’s linear, but they were also available as circular calculators – disks – often optimised for other functions such as electrical calculation. My father had one.

I have to admit that I’m using computers to do the maths for a hard sci-fi story I’m writing just now for an upcoming anthology. But still, the slide rule’s there as a standby. And the idea of it – well, I find that pretty inspiring. Do you?

## 11 thoughts on “My flirtation with the ultimate golden age sci-fi gadget”

1. I love the fact that a physical device shows mathematical relationships. It shows the mathematical/logical universe neatly and perfectly fitted into the physical world. Cool!

1. It is indeed very cool! As you say, physically showing math relationships in a very real way. Somethiing we risk losing sight of in this age of computers.

2. It is inspiring.

The slide rule was just before my time, but I respect it.

1. It”s a wonderful example of human ingenuity. I can get quick-and-dirty approximate answers out of it faster than I can push buttons on a calculator.

3. bevrobitai says:

Sadly I was maths-intolerant from an early age and never understood the delight others found in the subject. Slide rules were just annoying because I could never figure out which side had the right measurements to use as a plain and simple ruler.

1. My slide rule has a ruler across the top. In centimetres, which was annoying at the time because it was 1977 and metric measurements only meant something then if you multiplied a cm by 2.25. Luckily the slide rule was quite good at solving the 2.25 times table.

4. It’s amazing what has been achieved by earlier generations. A friend went to the Smithsonian and saw one of the Apollo capsules. He was shocked to note the control panel was made of wood. Wow! That’s just shocking to imagine. Men left Earth’s atmosphere with such crude technology. It’s unfathomable to consider…now. Just because something is old, doesn’t mean it doesn’t work. I’ve never used a slide-rule. I held one, once. That’s it. Division was taught to me with a wierd kind of shorthand. Long division was cool once I got the hang of it. With calculators, I haven’t used it in decades. I think it’s cool that Heinlein conquered space with slide rules. It’s the epitome of the moral in golden-age scifi: humans overcome the odds despite our technological deficiencies.

1. Apolllo was a simply stunning achievement for its day! When I think of golden age sci fi and slide rules the only name is Heinlein. One to conjure with. I still remember the sequence in ‘Have Spacesuit, Will Travel’ where he presented what amounted to a lecture on acceleration physics and slide rules, all seamlessly as part of the story. It worked!

1. Heinlein was a genius. 🙂