Slide Rules - whatever happened to them?

[BigMal]

Oh yes. Flexicurve. Still got one - it's in the same "junk" drawer as my sliderule.

[Nick C]

13 hours ago, EddieB said:

The mistakes were deliberate, so that any “stealing” (unauthorised copying) would be obvious.  I sometimes wonder if compilers of locomotive lists do the same!

Map makers certainly do - inserting fake streets etc.

9 hours ago, John ks said:

And a calculation done with a slide rule

 

 

Line the 1 on the slide with 2.102 on the body, move the Cursor (clear bit) until the hairline lines up with 1.3 on the slide & the number on the Body is the result 

Calculator result is 2.7326 . out by 0.0034

The accuracy depends on how accurately you line up the slide & the cursor

John

 

 

I don't understand that - how do you get 2.102 to start with? Surely the most accurate you can get is 2.11 as that scale is in 0.02 increments? (I was always taught that any measuring instrument is only accurate to half the smallest scale division)

 

I think I shall have to get myself a slide rule and learn how to use it...

[2750Papyrus]

10 minutes ago, APOLLO said:

Not got mine now but does anyone remember the Flexicurve, twin thin brass plates either side of a lead bar covered in plastic. About a foot long and half inch square, you bent it to (more or less) align with dots on graph paper then drew a line along it. Most useful at Tech.

 

Think you can still buy them.

 

Brit15

 

 

Yes, I had one of these.  It was in the garage (railway room) for many years but seems to have disappeared.

 

I did go my my Thornton drawing instruments box recently for a pair of dividers and was disappointed to find that the foam had crumbled and the instruments corroded.  A bit like their owner!

[Joseph_Pestell]

6 minutes ago, Nick C said:

Map makers certainly do - inserting fake streets etc.

 

 

 

I learned this when I made a complaint to Ian Allan about the "inaccuracies" in one of their atlases.  The "mistakes" are deliberate, they told me, to catch any people cheating on copyright.

 

I still think that 42 errors on 1 page is taking it a bit far!

[KeithMacdonald]

15 hours ago, Michael Hodgson said:

I do indeed mean tables.  Of course before we had computers log tables were produced by manual calculation, and I remember early mainframes being used to produce log tables (!) because it wasn't unknown for the printed manually produced tables to contain the odd mistake, either through mathematical error or mistakes by typesetters.  It was potentially a safety issue as such things might be used for navigation.  I wouldn't have wanted to be proof-reader for those!

 

Veering off topic (well, this is RMWeb), wasn't that Charles Babbage motivation for creating the Differential Engine? To calculate these tables without human error.

 

https://en.wikipedia.org/wiki/Charles_Babbage#Background_on_mathematical_tables

 

Quote

In 1812 he was sitting in his rooms in the Analytical Society looking at a table of logarithms, which he knew to be full of mistakes, when the idea occurred to him of computing all tabular functions by machinery.

 

[APOLLO]

11 minutes ago, Nick C said:

Map makers certainly do - inserting fake streets etc.

 

I don't understand that - how do you get 2.102 to start with? Surely the most accurate you can get is 2.11 as that scale is in 0.02 increments? (I was always taught that any measuring instrument is only accurate to half the smallest scale division)

 

I think I shall have to get myself a slide rule and learn how to use it...

 

 You get it as near as you can (or eyesight allows) - hence the name "guessing stick" !!!!!  

 

Brit15

[John Harris]

30 minutes ago, BigMal said:

Oh yes. Flexicurve. Still got one - it's in the same "junk" drawer as my sliderule.

 

I had a Flexicurve for my O level "Technical Drawing", I found it next to useless and drew curves by plotting the points and drawing freehand.  I passed the O Level, so I guess I was okay.

 

I also had small slide-rule, but pocket calculations arrived during my school days, so doting parents invested £32.95 in a simple add, subtract, multiply and divide calculator, which I still have.  This would be in the early 70s, so around £400 in today's money!  I never really took to log tables, they seemed a palaver compared with long division.

 

Dad worked at Ford in Dagenham, in the Standard's Room, and knew the bloke who calculated the gear profiles, for engines, gearboxes, etc.  manually using a slide rule.  Such applications were amongst the first the company used these "new fangled" computers for, after things like payroll.

 

jch

[EddieB]

12 hours ago, AndyID said:

 

Are they similar to French curves? I think I might still have mine somewhere although I have not seen them for a while.

To add to the confusion, they are also known as Burmester Curves or a Burmester Set. 

 

If I remember correctly that was how Rötring marketed their highly-prized and highly-priced sets, in obvious deference to their "designer", fellow German Ludwig Burmester, described in Wikipedia as a "kinematician and geometer" (I'd quite like those terms on my CV!). 

 

Me, I just graduated from a Helix school geometry set to a generic set of "French Curves" 

[Hroth]

1 hour ago, John Harris said:

 

I had a Flexicurve for my O level "Technical Drawing", I found it next to useless and drew curves by plotting the points and drawing freehand.  I passed the O Level, so I guess I was okay.

 

I also had small slide-rule, but pocket calculations arrived during my school days, so doting parents invested £32.95 in a simple add, subtract, multiply and divide calculator, which I still have.  This would be in the early 70s, so around £400 in today's money!  I never really took to log tables, they seemed a palaver compared with long division.

...

jch

 

I had some sort of flexible curve, green coloured and impossible to straighten out after use, more kinks than a dogs hind leg! 

 

My first encounter with an electronic calculator was in "Technical Drawing", the teacher brought this chunky box in, which had a Nixie tube display and told us that it was the future of calculation.  We all had a go, I probably tried 22/7! I had an early 4-function calculator too, its best feature was that you could get it to attempt to divide by zero...

 

2 hours ago, APOLLO said:

 

 You get it as near as you can (or eyesight allows) - hence the name "guessing stick" !!!!!  

 

Brit15

 

One thing we had drummed into us was that you should have a feel for the magnitude of the result you wanted, to be able to interpret the number under the cursor...

 

 

 

 

 

[The Johnster]

Lord knows what happened to mine, and I’ve long forgotten how to use one.  They are nice things to own, as are all precision instruments and should be kept on that basis.  It just feels wrong that a device that required such mathematic erudition to design and engineering precision to make should be discarded because it has been replaced by something cheaper and better.  

[Graham108]

I've still got my slide rule - must be 50 years old now. Never used it since i left school in the mid-(19)70's

 

Graham

[62613]

Somewhere, either myself or my no. 2 son have dad's slide rule, which was a "special"; he was a building services' engineer and, IIRC, it was used for calculating heat loads in buildings and stuff like that. What I do have are my 3 scale rules, all metric, as that's all I ever used for thirty years as a draughtsman.

[62613]

6 hours ago, KeithMacdonald said:

 

Veering off topic (well, this is RMWeb), wasn't that Charles Babbage motivation for creating the Differential Engine? To calculate these tables without human error.

 

https://en.wikipedia.org/wiki/Charles_Babbage#Background_on_mathematical_tables

 

 

Babbage had a mention on one of the programmes that BBC Bitesize are putting out for children, last Friday; but it was mostly about Ada Lovelace, who ruined herself attempting to get the money together to allow Babbage to build his machine. She, apparently is credited with the first attempts at programming.

 

 

[Fenman]

19 hours ago, Philou said:

I never had a slide-rule - just too expensive at the time and had to make do with log tables. I am glad that the electronic calculator came about!

...

In my first week at grammar school, we were each given a little pack of pre-printed card and paper elements from which we had to make our own slide rules.

 

I can’t imagine Norfolk County Council Education Committee would have frittered much money on us (there was little evidence of it anywhere else), so I’m surprised they were considered expensive. 
 

After hopefully grasping the basics, I remember us graduating to big white plastic jobs, with vastly more numbers on them than I had realised existed. I am not confident I ever learned enough to come close to its capabilities. Fortunately, pocket calculators started appearing a year or so later. The sciencey kids had complicated jobs from Texas Instruments; I had a nifty solar-powered Casio which got me through exams. 
 

Paul

[TheQ]

We were shown a slide rule at my first secondary school but that was as far as it went.

After that we used log tables.

We're were given a couple of sessions with a mechanical calculator and told they were the future.

Electronic calculators came in just as I left school, I bought a Maxwell scientific calculator for training college, it's still in a box somewhere...

 

 

[Philou]

@Fenman Cardiff Education Committee 1960s - likewise grammar school. Not much money about then AND I was one of five kids - so I did with tables and it's surprising what you remember especially if you use 'simple' degrees ie., 30, 45 and 60 - something stuck.

 

Cheers,

 

Philip

[APOLLO]

41 minutes ago, 62613 said:

Babbage had a mention on one of the programmes that BBC Bitesize are putting out for children, last Friday; but it was mostly about Ada Lovelace, who ruined herself attempting to get the money together to allow Babbage to build his machine. She, apparently is credited with the first attempts at programming.

 

 

 In The Science musem in London you can see this

 

 

Babbages Brain !!!

 

Brit15

[rocor]

16 hours ago, J. S. Bach said:

A Burroughs office photo from 1907, with at least two oddities:

 

 

 

I could not find the oddities in the photograph.

 

 

[Hroth]

4 hours ago, TheQ said:

We were shown a slide rule at my first secondary school but that was as far as it went.

After that we used log tables.

We're were given a couple of sessions with a mechanical calculator and told they were the future.

Electronic calculators came in just as I left school, I bought a Maxwell scientific calculator for training college, it's still in a box somewhere...

 

 

 

I've a Multo mechanical calculator, somewhat similar to that, which I salvaged when a company I worked for was throwing them out...

 

[Hroth]

3 hours ago, rocor said:

 

I could not find the oddities in the photograph.

 

 

 

We've run into some insurmountable problems Gentlemen, We've no internet connection for the Chromebook, and they haven't made any batteries for the printing calculator yet.

 

I'm afraid we'll just have to continue using the cylinder calculators for the time being...

 

 

[J. S. Bach]

5 hours ago, TheQ said:

We were shown a slide rule at my first secondary school but that was as far as it went.

After that we used log tables.

We're were given a couple of sessions with a mechanical calculator and told they were the future.

Electronic calculators came in just as I left school, I bought a Maxwell scientific calculator for training college, it's still in a box somewhere...

 

 

That thing looks more complicated than a slide rule. I want one!!

 

It also reminds me of an old-fashioned check writer:

https://i.pinimg.com/originals/ab/de/2f/abde2ff42bc5f09d7316e22e56f2a625.jpg

 

Edited January 25, 2021 by J. S. Bach

[Danemouth]

There is a film starring Leslie Howard about RJ Mitchell the man who came up with the Sptifire -  "The First of the Few"

 

In it we see Howard using a large cylindrical slide rule at one point. I didn't know they existed!

 

Dave

[John Harris]

22 hours ago, Hroth said:

 

I had some sort of flexible curve, green coloured and impossible to straighten out after use, more kinks than a dogs hind leg! 

 

My first encounter with an electronic calculator was in "Technical Drawing", the teacher brought this chunky box in, which had a Nixie tube display and told us that it was the future of calculation.  We all had a go, I probably tried 22/7! I had an early 4-function calculator too, its best feature was that you could get it to attempt to divide by zero...

 

 

One thing we had drummed into us was that you should have a feel for the magnitude of the result you wanted, to be able to interpret the number under the cursor...

 

 

That's the one, green and more "kink" than curve!

 

I worked in IT for years and in the early when we did financial runs the operations staff used to have to reconcile the figures, they had old style mechanical calculators with a handle to crank at the end to add them up.  I think they were thrown out, though I wish now I had rescued one.

 

jch

[John Harris]

4 minutes ago, Danemouth said:

There is a film starring Leslie Howard about RJ Mitchell the man who came up with the Sptifire -  "The First of the Few"

 

In it we see Howard using a large cylindrical slide rule at one point. I didn't know they existed!

 

Dave

 

Those cylindrical slide (twist?) rules are collectable these days and fetch a good price.

 

jch

 

 

[John Harris]

18 hours ago, 62613 said:

Babbage had a mention on one of the programmes that BBC Bitesize are putting out for children, last Friday; but it was mostly about Ada Lovelace, who ruined herself attempting to get the money together to allow Babbage to build his machine. She, apparently is credited with the first attempts at programming.

 

 

 

For a fairly accurate, yet amusing, account of Lovelace & Babbage, I can recommend this book.  As the title suggests, it's "mostly accurate". but I think it's worth a read.

 

jch