Log-antilog table booklet

I also have both slide rules and Castle's log tables, neither of which have been used for many a year. But, with a little effort, I CAN still use them and for all sorts of complex calculations involving indices, not that I've ever needed them. However, I would challenge anyone brought up in the calculator/computer age to use them in the event that electronic goodies were not available.

I don't know how true it is, but I've always understood that using the mechanical methods, although not as fast or as accurate as electronic methods, did at least give the user a feel for whether or not the answer was feasible or not. In support of this, I can relate two examples of where electronic devices have been proved to be incorrect due to possibly bad programming by the program writer(s).

The first was a calculation involving, from memory, as attempt to calculate the daily interest on a given sum given the annual rate. Using a particular make of calculator gave a wrong answer depending on the order of the calculation. It turned out that this machine ignored anything beyond the 16th (or maybe the 8th, it's a long time ago) decimal digit, whereas an equivalent Casio always gave the correct answer regardless of the order of calculation.

The second was a demonstration by a colleague who was into mapping underground caves and was using Microsoft Basic to perform the calculations. Again, memory is hazy, but I think he was using horizontal and vertical co-ordinates to determine a particular point, and then as a check, reversing the calculation. He did not end up back where he started. It turned out that he was using the standard single precision values. Double precision, I seem to think cured the problem. Interestingly, my Sinclair Spectrum did not display the same problem yet I seem to think it only used one byte more than Microsoft's single precision.

All that is newer, is not necessarily better.

Regards,

Peter G. Shaw

My personal archive has two little pocket books from the Henry Ford Trade School. One is a 6 figure log and Antilog book and the other is its matching Trig tables complete with diagrams for solving triangles, escribed and inscribed circles etc. These were given out as part of the training of apprentices at Radway Green in the 1950s, sadly no longer offered today.
I remember that the badge of office of all aspiring draffies was the Faber Castell 5" slide rule hidden in its little green pouch, usually in the breast pocket of a laundered overall. It was not particularly accurate, but with regular use good meaningful answers to problems could be quickly arrived at. A 10" version was kept in the drawer under the drawing board for more serious calculations!

Bob D

I own a slide rule and know how to use it, and I'm a hopeless romantic for old-fashioned things like 8-bit computing

But I have had to accept a few things:

An autofocus camera takes sharper pictures than I can.
A digital tuner tunes an instrument better than my ear.
A cheap digital calliper or mike is as accurate as me with a vernier one.
I make fewer errors with a digital calculator than doing mental maths.
I can proof read better using a pdf than a paper copy.
The microwave burns less food than the oven

All is not lost though, I still have an analogue wife and prefer FM to DAB!

It is horses for courses, and I suspect that the applications you list could all be addressed better by a computer (even using a spreadsheet) with a little imagination - I often get a spreadsheet to generate graphs of various scenarios or to compare gear ratios to get the best for a particular purpose, for example.

The irony with Peter's story is that single-precision numbers give you better accuracy than a slide rule, six significant figures where working to four is optimistic with a standard slide rule.. so I would guess that your speleological friend would have been even further out if he had worked out his route back using a slide rule.

I've looked it up and Peter is right about Sinclair BASIC using 5-bytes (like my beloved BBC computers!) rather than the 4 of a normal single-precision 'float'.

Neil

I've been looking for my log tables but can not find them. I did find my old slide rule but the plastic scales fell off, damp. Can't find my pride and joy "good" slide rule. When electronic calculators came out the usual question was " what's the point of 6 decimal places when all you want to know is should we use 3" angle or 4" ?"

I remember those too. They were published by the boss of the Ford Trade School at Dagenham (whose name escapes me now) although the data were produced by apprentices working hours on (mechanical) calculating machines. Being dumped on for that job was considered the equivalent of being sent to the salt mines. He was publishing a revised issue so a lot of this was going on when I was there (~1961).

I ought to have those books somewhere, wonder where they went - I never throw anything like that away.

I dunno about pdf's - don't have much call to proof-read those - but this sure doesn't apply (for me) to proof-reading drawings on the screen. No matter how much time I spend checking before printing, I see error(s) at the first glance of a printed page.

To John Knight

John

Failing all other courses I would welcome your kind offer

'Lake House'

Clun

SY7 8NY

Tony

Yes but it usually focuses on the wrong thing - and anyway, by the time it's sorted everything out the thing you wanted to photograph has gone.

Russell.

Hmmm Russell

I think maybe you need to get a newer autofocus camera!

Norman

Got the little 6" slide rule that dad had at the E&W(Wireless) school RNZAF Wigram around 1942, it' "The Unique Log--Log" slide rule made in England, I think they got them as a kit set. It's wooden, with celluloid pinned on. The cursor broke many years ago, I suppose a new one could be made. With dad's eyes I would think he would need a magnifying glass to use it!

Ian S C

Well chaps here's my small anecdote from when calculators first arrived, I was working on production and tool room jig boring at the time, Newall 1520 & 2436 machines, all calculations, and there were many, had to be done with 7 fig logs and we used a mechanical pin wheel calculator do achieve this.

The firm bought us a Texas Instruments scientific calculator and at first we would do the calculation and the "magic box" produced the answer, well being untrusting of this new fangled gadget we proceeded to " check" the result on the old mechanical machine. It was of course correct but ! ! Just in case ! A hole in the wrong place and a lot of money went down the drain. The pin wheel machine was "rescued" by my one time apprentice some years later when it was on its way to the skip.

Cheers John

It was only when a tutor explained that a slide rule was a set of log tables plotted out in linear form, that I began to understand how to use it. Eventually, with a Faber Castell Log-Log rule, (I still have mine over 50 years on) it was (note WAS) possible to work to two decimal places.

Surely, if it appears on a computer screen, it must be right mustn't it?

Someone said that CAD was an abbreviation for Computer Aided Disaster. In , or under, the wrong hands, it probably is.

(Tongue firmly in cheek)

Howard

Edited By Howard Lewis on 09/10/2014 23:51:59

Dug out one of my slide rules, and am struggling to understand all it's functions.

It's like this:

"Thornton No P221 Comprehensive duplex plastic slide rule with plastic cursor. The 27 scales are: LL01,LL02,LL03,DF{CF,C1,ISd,ITd,Td,Sd,C}D,LL3,LL2,LL1//S,ST,T,A{B,L,K,C}D,D1,Ps,Pt. The rule is complete with instructions and black vinyl wallet. Thornton’s most complex rule. Later renumbered AA010."

Despite the glorious complexity, there's one on ebay for £12!

It worked out 19x17 about four times faster than I could do it in my head I have a nice little pocket book on how to use slide rules, it's probably the toughest read since my statistics text book.

Neil

Hi, well I still have my late brother's British Thornton P271 slide rule, but it hasn't been used in anger for 41 years as I've no instructions for it. I can use the basic part, but haven't really had need to for many a year.

I can remember him working out quite complex and long winded equasions with it in his head, he was very good at maths.

My maths has never reached the grade of my late brother and I had a much simpler slide rule from Boots which I used to use at Tech, it was allowed in exams but electronic calculators were strictly forbidden. My one had a reversable slide for the log log ect. I've still got the instruction for it, so can brush up on its used if I ever need to.

I also have four and five figuer log and other tables by F Castle and printed by Macmillam Education Ltd. these were also allowed in exams. I haven't used these in years either. I nearly always use an electronic calculator these days, as it's normally the best answer I can get now, can't trust my mental arthematic to much.

Regards Nick.

Several reasons...

You need a better signal for DAB to be listenable without cutting out. Most of the stations my radio detects won't even play 90% of the time.

The bit rate for anything except BBC stations is so low that they are noticeably inferior to FM, even to my ageing ears, when you get a good signal.

Virtually all of the stations I like to listen to are in mono on DAB.

I remember the revelation when Radio 1 was able to make broadcasts in FM (back in the days of Tommy Vance).

All DAB has done so far is allow me to enjoy a genuine AM radio experience without the dial twiddling!

Neil

Neil

You could always move.......................

N

(...... ..and if Radio 1 is your thing then a crystal set and headphones would probably do )

N

Edited By NJH on 10/10/2014 13:40:54

Edited By Anthony Kendall on 10/10/2014 15:41:57

Edited By Anthony Kendall on 10/10/2014 15:52:00

> and if Radio 1 is your thing then a crystal set and headphones would probably do

Not since the days of Mark and Lard!

Today it's Radio 4 and Planet Rock

@Tony

Hmm - FM baseband has 15Khz bandwidth -at least as good as my ageing ears even if the stereo information hasn't got such wide bandwidth - at least it's there!

I'm sure a good DAB signal with stereo an 240 kbs sounds great, but even some of the BBC stations are only 80kbs mono. A non-BBC station I can almost receive is 48kbs stereo...

Neil

Neil,

I'm in a supposedly good area for both DAB and FreeView reception, and we listen mostly to Radio 3.

The audio quality on both streams is very variable ... according, I believe, to the bit-rate in use [for the recording and/or the broadcast] ... When it's bad, I simply can't bear to listen ... the digital harshness sets off something similar to tinnitus, although this is not a condition that I suffer.

Like you, I am much more comfortable listening to FM [although, yes, I am fully aware that the broadcast material has been 'digital' for many years].

I don't fully understand how DAB works; but I think there is a lot of lossy compression involved, and I certainly don't like the audio quality.

MichaelG.