Wednesday, June 27, 2007

Slide Rule

My favourite author is Nevil Shute. He wrote many novels including No Highway, which I studied for my O Levels in 1968 and A Town Like Alice. Both have been made into movies. Nevil Shute was an aeronautical engineer by profession and he also wrote an autobiography entitled Slide Rule.

Slide Rule - Nevil Shute

Now, I have a question for the young people (below 30). Do you know what is a slide rule?

If you have never heard of a slide rule, do not feel embarrassed. I once put this question to my nephew, a polytechnic graduate, and he too did not know what it was. To my surprise, so did a few other young people I put the same question to.

Here’s another question. You must watched documentaries of the 2nd World War and seen some of those amazing fighting machines like air craft carriers, submarines or even Hitler’s inter-continental ballistic missile, the V2. In fact, at the time of the Korean War, in the fifties, when the jet fighter started to be used, or during the early part of the space race in the 60’s, the electronic calculator had not arrived yet. To design, produce and operate these engineering marvels must have required an immense amount of mathematical calculations and data crunching. How on earth were they able to do it when they did not even have a simple electronic calculator? Has this question ever occurred to you?

The answer is the slide rule and its cousin the log book (which we learned to use in secondary school). According to my dictionary, the slide rule is “an old-fashioned instrument that looks like a ruler with a middle part that slides, used for calculating.”

Do you know that the ubiquitous calculator that even the vegetable seller in our wet markets use nowadays was not around until the 1970’s. I remember my university days in the early seventies. We had to use the slide rule for all our calculations. Although, the scientific calculator was available by then, we were not allowed to use them for our exams. The reason is that they were simply too expensive and very few students could afford one. For example, did you know that an HP scientific calculator cost more than $1,000! I had the chance to use one courtesy of my brother-in-law who worked as a refinery technologist.

(Well, actually at that time, he was courting my sister, and maybe wanted to impress me by lending me his precious HP scientific. I remember bringing it to class and getting my class mates all envious.)

Slide Rule 1

Although, I have been advising my readers to get rid of things they do not need (in my other blog ), I am really glad that I did not throw away my slide rule. In fact, it is still in very good condition complete with protective case and instructional manual. Mine was an expensive model from Faber Castell. It was made of 'Geroplast' and cost slightly more than $30. The cheaper ones were usually made of bamboo and imported from China.

Slide Rule 3

Slide Rule 2

The slide rule is one of those human inventions that was seen as an essential tool one day and then became obsolete practically overnight with the arrival of the pocket calculator. Here’s an interesting snippet about the slide rule from Wikipedia:

“Throughout the 1950's and 1960's the slide rule was the symbol of the engineer's profession (in the same way that the stethoscope symbolized the medical profession). As an anecdote it can be mentioned that German rocket scientist Wernher von Braun brought two 1930s vintage Nestler slide rules with him when he moved to the U.S. after World War II to work on the American space program. Throughout his life he never used any other pocket calculating devices; slide rules obviously served him perfectly well for making quick estimates of rocket design parameters and other figures. Aluminum Pickett - brand slide rules were carried on five Apollo space missions, including to the moon, according to advertising on Pickett's N600 slide rule boxes.”

How to use the Slide Rule? Sorry to say that apart from simple multiplication and division, I have forgotten. And I am too lazy to read up the instruction manual just to explain it here. But if you are really interested, I have listed a few websites below which explain in detail how to use the slide rule.

Still, I hope you learned something new today.

Wikipedia Slide Rule Site
Eric’s Slide Rule Site

How a Slide Rule Works
Another great slide rule site


JollyGreenP said...

I remember them well. My first one was also a Faber Castell bought when I was in the sixth form doing A level Chemistry and Physics. Sadly I no longer have it, but it also saw me through HNC Chemistry and HNC endorsement in Instrumental Analysis. At work we used the black truncheon like slide rules where the scale was printed in a spiral effectively giving a lot longer scale in a shorter space and allowing an extra degree of precision in the calculation. We used them for calculating analysis results for moisture %, reducing sugar %, dextrose equivalent and sulphur dioxide content of glucose syrups.

John H

Lam Chun See said...

Hi John. Nice to see you (adult) photo for the first time.

I forgot to mention to mention my slide rule cost around $30.

aiyah nonya said...

Hey , I remember seeing that when I was young - the wooden type. But had no idea what it was for. Since then I have forgotren all about it.

Thanks for the info.

zen said...

Slide rule is like greek to me but we did use the log book in secondary school. As for Von Braun, who was Hitler's youngest scientist (rocketry). Luckily he was captured by allied forces in 1945, otherwise he would be working for the Russians. Later he became one of the pioneers spear-heading the US space progamme. I remember when the Port first introduced the use of calculars, every storekeeper was given one, and it was treated like a piece of rare gem to be kept under lock and key. Only the warehouse chief was allowed to use it. Now no one even give a second look on a multitude of calculators displayed in a roadside stall.

Victor said...

"Don't know what a slide rule is for."

Of course, if I had said that, you'll know that I'm lying. But I am actually quoting a line from the lyrics of the 1986 Sam Cooke song, Wonderful World:

"Don't know much about geography
Don't know much trigonometry
Don't know much about algebra
Don't know what a slide rule is for."

I am not surprised if most of your young readers say the same thing though.

But isn't it wonderful that our world has gone through so many good changes in a short span of just a few decades?

Laokokok said...

Wah Chun See, thanks for the reminder. I've almost forgotten all about this word "Slide Rule". One thing is for sure, I've long forgotten how to use it hehe.

Lam Chun See said...

Thanks Victor for reminding us about that song. See if I remember correctly. The first version was by Herman's Hermits. A more recent version had 3 male singers; Art Garfunkel, James Taylor and 1 more chap, I think.

Lam Chun See said...

For a moment there, I thot Zen said 'geek'. Of course that term wasn't popolar yet during the slide rule era. But if it did, I would picture a geek as someone holding a slide rule.

Lam Chun See said...

I forgot to mention in my post that my favourite author, Neville Shute wrote an autobiography entitled Slide Rule. He was an aeronautical engineer by profession. Which goes to show engineers can be creative (in the literary sense) and can be good writers too.

zen said...

I was quite amused when one of my former officers went through my prepared memo, word by word, eyes widely opened, as though verifying an important contract. But after finding a few spelling mistakes, for such a short comment in the above blog, and in reflection I believe my officer was correct in being extra careful when coming to supervising his staff.

Brian Mitchell said...

and before the slide rule there was of course the abacus - I recall seeing one used by one of the shopkeepers near my home in Toh Drive just off Upper Changi Road. I think we used to catch the school bus or gari there and I often had a few minutes to watch those coloured balls flying back and forth - perhaps you can identify some pictures of them in use is old Singapore Chun See?

And strange that you should also like Nevil Shute, he was someone I read a lot in my youth and I recall at my first interview for a University here in the UK they asked me about my favourite authors and I listed Shute first of all.

Lam Chun See said...

Brian, Nevil Shute is also Lynn Copping's favourite. Her favourite book is A Town Like Alice. Like me, she also likes Requiem for a Wren.

Hey, maybe this can be topic for another article.

Brian Mitchell said...

I shall look out Requiem for a Wren as I don't recall it - mind you its many years since I read Shute so I may have read it and not remembered it. Another of Shute's books was of course On the Beach made into a rather good (if depressing) film about the post nuclear war world

JollyGreenP said...

neville Shute owned and ran an aircraft factory in the centre of York about ten minutes walk from where i live now. The building is currently standing empty now but I remember it being used as a car garage, a car hire hire storage building and the last use was as one of those lazer battle entertainment venue which has now gone bust. There is a photo of the building on Flickr URL is

John H

Lam Chun See said...

John. Thanks for that bit of info. Actually, I quite like to take photos of old buildings which are disappearing fast in Spore. Unfortunately, it takes a lot of time. On the other hand, my wife likes to make comments like; "that building is so old and ugly, and stands out like a sore thumb amidst all the new buildings".

zen said...

An old building looks like a sore thumb and ugly is because its dressing has not changed through passing years. A few months ago, I had dinner with my sister at the Old Majestic Theatre in Chinatown. The grand lady is now eighty years old. It has presently been given a new dress, makeover and revitalised into a small cosy shopping venue cum eating place, worthy of its presence in vibrant Chinatown. In short, old buildings need a new lease of life to stand up and be noticed by people, in the midst of Singapore's progress.

JollyGreenP said...

I agree with Zen, the Majestic is a wonderful building and shows how with a bit of Tender Loving Care (TLC) an old building can be brought back to life. I think I first noticed The Majestic in 2003 on my last working trip to Malaysia. I had finished in KL on the Friday but couldn't get a flight home until Sunday night and so had to stay in Singapore for the weekend. The majestic was one of the buildings I visited and I think that it had just reopened in time for CNY and was festooned with red lanterns which in no way detracted from the wonderful art deco decoration of the building.

John H.

zen said...

jollygreenp - As a seasoned traveller, indeed you know where places of interest are, especially in Singapore. When my sister asked me where to meet for dinner at Chinatown, two places flashed across my mind the twin iconic theatres of Majestic and Oriental (the younger one), and I suggested Majestic. I was quite sure my sister couldn't miss the place.

amy said...

Hi Chun See! :)

FYI, the link to Eric's site should be:

(I've amended this on your post on

Lam Chun See said...

Thanks Amy. I am always a little clumsy with html links.

Anonymous said...

Thanks for the wonderful memories.
I took my O levels in 1976. We had to learn slide ruling from Sec 3 , although it was not mandatory to sue it. I continued to use slide rules until my first term at NUS in 1981 (after NS), at which time calculators were suddenly the norm.
I still love slide rules and wish I didn;t lose mine all those years ago.