Slide rules!

[Aicchalmers]

Just been playing around with one of my ol grandads, really quite fast and not so complex once you get used to it .. appeals to my core luddite

Any tips for learning how to use them or just keep practicing and looking up?

Is there any board feet, cubic meter etc forestry slide rules made anybody knows of?

Oh and Nuclear Fallout Radiac Slide Rule (ca 1950's). | eBay

Although I do agree with the seller

PS if anybody has any interesting ones spare I'd be interested in buying

[Stubby]

I had one when I was at school . As I recall I used to have the formulas for things I was wobbly on written inside . When I slid the center out there they were !

[Aicchalmers]

See they're banning kids from using calculators in primary school now .. I reckon teach them to use slide rules and they'll be a hell of a lot better off

[daltontrees]

I still have one and use it now and again. Tey work on the principle that multiplying two numbers together is the same as taking the log of both numbers, adingthem and then taking the antilog of the answer.

 

e.g. multiply 7.35 by 17.2.

 

log 7.35 = 0.8662

log 17.2 = 1.2355

sum = 2.1017

antilog = 126.38

which is the right answer

 

The great thing about them is you don't have to do any of the calculations or even know what logarithms are.

But where they really come into their own is if you have to multiply the same number by lots of different numbers. So if you are paying say £43.50 a metre for fencing materials, set upthe slide rule and you can read off the total price for 23 metres, 11 metres, 94 metres, 55.5 metres etc. No need to adjust the slide rule. As quick as that, no calculator, no pen and paper.

 

Could be used the same way for converting feet to metres, metres to feet, pounds to kilos, litres to gallons. The accuracy is only as good as your eyesight.

[GardenKit]

Haha, Stubby, thats just what I did too. All scratched very neatly into the plastic with the point of my dividers.

Exam cheating, but it worked!

Before the days of the calculator.

[Stubby]

Haha, Stubby, thats just what I did too. All scratched very neatly into the plastic with the point of my dividers.

Exam cheating, but it worked!

Before the days of the calculator.

 

:biggrin: