Talk:Slide rule/Archive 1

Addition and subtraction
I included a new section to expose the lesser known technique for performing addition and subtraction on the slide rule. While the linear method isn't exactly advanced, the dividend/quotient method retains the advantage of keeping the working total directly under the cursor. This is extremely convenient for performing functions that require an addition or subtraction component without resorting to pen/paper. Both pen/paper and the quotient method may introduce a slight amount of error. With pen/paper you introduce some error from reading then returning the value back to the slide. With the dividend/quotient method, this same conversion is performed when you carry the 1. Both have the same potential for accuracy / error introduction. Mentally, I prefer to add/subtract 1 and let the slide rule do the rest. Drakcap 22:58, 21 January 2007 (UTC)


 * The division + 1 method is really a trick, not a useful method, as it requires reading the result, adding one mentally, and then moving the cursor to the result. Pen and paper allows a much easier check on the arithmetic. You don't need to have the L scale on the slide; set the cursor on the body L scale for the first value, note the value on the slide, set the index to the slide, move the slide to the noted value, read result on L. Same error problem as the first. htom (talk) 05:44, 13 August 2008 (UTC)

Obsolete or not?
Are slide rules completely obsolete? Surely they'd be useful in places or situations where there is no electric power, or as a backup.


 * Solar-powered claculators generally fit the bill, and are now cheaper to get than (now antique and no longer made) slide rules. Some older engineers who owned slide rules and know how to use them do indeed use them as a (nostalgic) backup, but even that use is uncommon.  They can be useful in education, though--I had a math teacher who hauled a bunch out to teach logarithms quite nicely.  Also, as the article says, airline pilots are still required to have and understand specialized circular rules.


 * My brother-in-law is a cop. He had to learn to use a slide rule, for accidents. Specially marked, I'm sure. I don't know how much they use them. Solar power calculators are good, but they don't always work in dim light. Saros136 23:54, 21 January 2007 (UTC)

We were still using slide rulers in 1975 (United States). However, people were starting to get calculators around 1973. The add/subtract/multiply/divide only calculators costs about $80 at that time. Spevw 22:49, 18 August 2007 (UTC)

"Obsolete" has clear definitions. Slide rules had not fallen into disuse by 1973. Electronic calculators had not become household items and were uncommon among lower middle income people, and a novelty among those who could afford them. The general public was not spending hundreds of dollars for something they could do without, and it wasn't until the price hit $10 that it was accepted as an everyday item. In 1975, a deep discount store in NYC introduced a $10 calculator and there was a nonstop line to buy them. It was literally unheard of for a price that low before then. That is not of much relevance since it was far from the functional equivalent of a slide rule. Schools still prohibited calculators since they offered an economic advantage/disadvantage to students. Prices did not drop to that point in the market as a whole until much later. An HP-35 would have been needed for grade school tests, and one still cost in the hundreds of dollars. They were banned from the SAT and similar tests until much later. By the end of the 1970s, prices had dropped to the level that made calculators common consumer items, but they were still not well accepted by educational institutions.

I can talk from experience, which is certainly not good enough for an article, even if accurate. Likewise, the statements in the article regarding obsolescence need a citation. Wikipedia does not allow opinion and there's nothing suggesting that this is general or common knowledge. Hagrinas (talk) 20:43, 30 April 2010 (UTC)
 * Okay .—Mark Dominus (talk) 03:01, 1 May 2010 (UTC)

Does anyone know if it is true that C-130 Hercules aircraft come with a slide rule fitted so that the cargo handler can work out the optimal storage of the transportable goods so that they will not put the flight in danger? If they are still used in this manner they would not be obsolete. 86.44.75.184 (talk) 11:25, 20 March 2011 (UTC)

Size of rule pics
The instructional slide rule illustrations are great, but could they be reduced in size somehow, without destroying the instructional value? The present figures exceed the width of a web browser window even at high resolutions. --Wernher 00:00, 19 Apr 2004 (UTC)


 * I have now scaled down the pictures a little. They obviously can't be scaled down much further without the markings becoming undistinguishable from each other, but the present size at the very least should be more suitable than before. --Wernher 23:37, 26 Apr 2004 (UTC)


 * I drew the instructional pictures, and I could redraw them to a new width if desired. But (1) when you say "they exceed the width of a web browser window" you mean they exceed the width of your web browser window; regardless of how small I make them they might still exceed the width of someone's web browser window.  So how would I decide how wide to make them?  And (2), even if they do exceed the width of your web browser window, so what?  I do not see what the problem is.   Please explain.  -- Dominus 10:14, 27 Apr 2004 (UTC)


 * What I meant was that, as I said in my first comment, even at high resolutions like with my own browser window (roughly 1000 pixels wide, of which perhaps 800 is available for articles after Wikipedias left margin is accounted for), the pictures exceeded the window width and thus necessitated sideways scrolling (the "so what"). This should answer your two questions. In principle, yes, one never knows how small a browser window anyone uses, but one may assume that few users today strive with less than 800&times;600 pixel displays (and with the falling prices on 15" LCD screens of 1024&times;768 resolution, and the related sharp price drop of CRTs, I suspect that even 800&times;600 will soon be a thing of the past including almost all budget installations). --Wernher 17:58, 27 Apr 2004 (UTC)


 * With IE and Opera at least, there is no problem with wide pictures: they do not make the text wider as well.--Patrick 10:49, 27 Apr 2004 (UTC)


 * Yes, a good thing, no problems with the text; but still I think one should try and avoid the need for sideways scrolling entailed by very wide pictures. --Wernher 17:58, 27 Apr 2004 (UTC)


 * Sorry, I still don't understand. Yes, having wide pictures means that you have to scroll to see the whole thing. But you shouldn't have to scroll to see the parts of the diagrams that are referred to by the article text, so I don't see why this matters. In my opinion, it's more important that the part of the slide rule that is disucssed in the text be clear and legible than it is for the other parts to be visible at all.  If you like, I can chop the rightmost end off of each picture; then they will fit and you won't have to scroll. -- Dominus 15:40, 28 Apr 2004 (UTC)


 * I must say I had no intention of stirring up this matter into some kind of 'hot' discussion. The pictures as they stand now is perfectly all right, and with my infinitesimal changes they are also within the width of a much larger proportion of the reading public's browser windows. Not all readers, of course, but I dare say many more than before. So why spend more time on this? I have no problem seeing it from your/the general point of view, but I can't quite say I see any motivation for much further arguing about the matter as it stands. --Wernher 02:28, 29 Apr 2004 (UTC)


 * That is not responsive to my questions. Since you don't seem to have a good reason for your change, and since you dont seem to want to discuss it, I am going to put it back the way it was.  Thanks for your other contributions to this article.  -- Dominus 11:26, 29 Apr 2004 (UTC)


 * Well, if that's how you feel, how about your earlier suggestion of chopping off the rightmost non-essential/ instructional part of the pictures? I still feel there is some merit in trying to avoid sideways scrolling. And I have no problem discussing this -- in fact I very much want to do so, contrary to the impression you may have got from my comments. In that case I have not expressed myself clearly. As the discussion stands now, I almost feel some kind of hostility(?).  --Wernher 21:36, 29 Apr 2004 (UTC)

Photo overlapping TOC

 * Hi, Wernher -- I reverted your change to the location of the first photo, because it wasn't rendering properly in Firefox -- the photo was coming out on top of the table of contents. Hope that's OK. Reading over your dialog with Dominus above, I agree with you that Dominus's figures were too wide. Although he's right in theory that scrolling to the right is not necessary in order to understand the figures, it looked ugly, and the reader would not necessarily realize when first going through the examples that scrolling was not needed. I've tried to solve the problem by replacing the figures with new ones representing single-decade scales rather than double-decade ones. This allows all the examples to fit within a comfortable width. --Bcrowell 04:54, 30 Apr 2005 (UTC)


 * Heh, this is interesting: the reason I changed the location of the uppermost photo in the first place was that it came up on top of the table of contents! :-) Strange. Or does it mean that my browser (no prize for guessing which one...) places the TOC on the left hand side by default while Ff does the opposite? Oh well. I think we might have a "double Murphy" here. BTW, thanks for fixing the other figs. --Wernher 05:14, 30 Apr 2005 (UTC)


 * Ugh -- what a pain! My browser also puts the TOC on the left, but the overlapping happens when I use "right" for justification, not when I use "none." So are you saying that in its current state, it overlaps for you? Its current state is "Image:pocket_slide_rule.jpg|frame|none|A slide rule being used to multiply by 2. Each number on the D scale is double the number above it on the C scale." In this state, it does not overlap for me. --Bcrowell 15:14, 30 Apr 2005 (UTC)


 * I've posted at the Help desk to see if anyone knows how to fix this. --Bcrowell 17:13, 30 Apr 2005 (UTC)


 * I tried adding a fix suggested by the help desk. Wernher, can you tell me if it fixes it?--Bcrowell 15:06, 1 May 2005 (UTC)


 * Nope, the photo still appears above the TOC, leading to unnecessary waste of vertical display area IMO. :-( Hmm, perhaps the question then becomes: what is the most common browser as of this writing? Should one let that decide what code to use? Or, is that a despicable view, since it may depend on an error in the rendering engine in the dominant browser (how do we determine which browser is at fault, BTW?). --Wernher 00:54, 4 May 2005 (UTC)


 * Oh, I see -- you just don't want it above the TOC? You must have a wide screen -- on mine, there's no possible way for that wide figure to fit side by side with the TOC. I think it's right the way it is.--Bcrowell 04:14, 4 May 2005 (UTC)


 * Argh, now I understand---I misunderstood the term "on top of" to equal "above"... Now, what you have been telling me all along is that the photo actually overlaps the TOC like a "double exposure"? That I most certainly agree is a Bad Thing&trade;. :-) You see, I was about to suggest the following: "If the figure turns up above the TOC for you (and likewise for others with not-very-wide screens) no matter what we do with the WKP src code, why not use the scheme anyway---so that everyone get what they want? :-) There's not any drawbacks with that, is there?" But that is really not an option if I understand you correctly, then. Oh well. As the laywers say (on TV, at least): "I have nothing further"... Sincerely sorry for wasting (y)our time. --Wernher 11:25, 4 May 2005 (UTC)

Sci/eng calcs
The rationale behind my qualifying the word 'calculators' with 'scientific/engineering' in the intro paragraph is that slide rules were not essentially replaced by simple four-function calculators unable to compute trigonometric and logarithmic functions as well as roots. Only with the advent of scientific pocket calculators were slide rules definitely obsolete, although the price point of those calculators kept them out of reach for large parts of the potential user base until the latter half (the end, really) of the 1970s. --Wernher 11:48, 17 Aug 2004 (UTC)

Listing on Peer review
This article has been listed on WP:PR to gain wider commentary. Please see the comments there and try to help collaborate in improving this article. Thanks - Taxman 22:41, Aug 23, 2004 (UTC)

These are the comments from WP:PR; this article has now been removed from that page due to inactivity. Alanyst 17:40, 18 Sep 2004 (UTC)

Peer review comments
Thinking of nominating this for featured status. Anyone interested in helping? Seems to be a very good start. Alanyst 02:52, 15 Aug 2004 (UTC)
 * The opening sentence seems a bit odd- it defines the slide rule solely by contrasting it with an instrument that replaced it. How about someting saying what the slide rule is, not what it isn't? Markalexander100 05:56, 15 Aug 2004 (UTC)
 * Good suggestion. I have revised the intro.  Anything else?  Alanyst 15:00, 17 Aug 2004 (UTC)
 * Good article. I like it.  A few notes:  The history section needs to be expanded.  When were they first used or developed, and what were the precursors?  Also the section on standard linear rules says 2 or 3 significant figures of precision are possible, but I thought with custom, longer units, higher precision was possible?  I remember looking at the Guiness record for the longest slide rule.  In addition a picture of a circular slide rule would be very good to show the contrast.  I had never reallized there were circular slide rules.  Mention of the cultural impact of slide rules being so widespread and then replaced so that current students only learn about them as a history lesson might be appropriate.  I think the slide rule is the MIT or MIT math club symbol too. - Taxman 20:39, Aug 19, 2004 (UTC)
 * I'd like to point out that the scales in the figures don't look quite right; some numbers seem to be positioned linearly instead of logarithmically. For example, 4.5 is shown midway between 4 and 5; that physical location should correspond to (approximately) 4.3.  --Coneslayer 21:46, 2005 Mar 10 (UTC)
 * Never mind, I was thinking wrong. --Coneslayer
 * You were thinking more or less correctly---the 4.5 mark should not in fact appear midway between 4 and 5. The distance between the 4 and 5 marks is log(5) - log(4) = 0.223, and the distance between the 4 and 4.5 marks is log(4.5) - log(4) = 0.118, so the 4.5 mark appears 0.118/0.223 of the way from the 4 to the 5, or about 53%. Careful inspection of the diagram will reveal that it is indeed slightly more than halfway over.  I very much appreciate that you took the time and touble to examine the diagram so carefully.  Thanks!  -- Dominus 14:49, 11 Mar 2005 (UTC)

E6B or E6-B or E-6B?
The "E-6B" name variation used in the article was never introduced to me by any of my flight instructors. They used E6B or E6-B. However, a google test says that all of the spellings are widely used: E6B - around 20,000 E6-B - slightly over 10,000 E-6B - (the one used in the article) - the least popular, albeit just about 10% less than E6-B

Change to E6B? BACbKA 10:21, 27 Sep 2004 (UTC)


 * I just created a new article on the E6B for Wiki; very very rough outline, but it's there. I'm using 'E6B', and just edited this page to use that format. I've even see people use all three spellings in the SAME paragraph elsewhere. Comments & help with the new E6B article welcome! --Madpilot 02:16, 13 Mar 2005 (UTC)


 * Ah. As you can tell from my recent lengthy entry in the E6B history section, the original military name was E-6B. Later manufacturers apparently moved or removed the hyphen to, I don't know, perhaps avoid copyright problems.  In any case, the most popular one sold today is named E6-B, which causes a lot of people to assume that's the original name.  It is not, and frankly, it drives me nuts , because it's helping people to lose a precious piece of history.  But I'm willing to put up with E6B, which doesn't have the same commercial ring to me.  --Kevindarling

von Braun photo
I would like to have some comments on the photo of von Braun which is used in the article about him -- I wonder if that is one of his slide rules being partly visible in the picture. Please comment at the photo's talk page. --Wernher 15:39, 10 Dec 2004 (UTC)


 * Bah -- the photo was removed a while ago due to copyvio doubts. The replacement photo does not show any trace of what I believe might have been a slide rule. Oh well. I might try to find the original photo somewhere, though, just to have a closer look. --Wernher 8 July 2005 00:53 (UTC)

Inventor
While I see many people mentioned, I don't see one I've heard credited, Peter Roget. Comment? Trekphiler 10:20, 14 December 2005 (UTC)


 * Roget invented the log-log scale for powers and roots. Dicklyon 15:42, 29 April 2006 (UTC)

Scale Length
I think it's unecessarily ponderous to talk about the scale length to 3 significant figures of precision. And, on this Staedtler-Mars No. 94428 I have here, some of the scales are 250 mm long and some are 270 mm long - this is done so that numbers a little bigger than 10 or a little smaller than 1 are still readable. --Wtshymanski 22:53, 10 February 2006 (UTC)


 * If you check, I think you will find the distance between 1 and 10 on the C and D scale is exactly 250 mm, to limits of their manufacturing precision. All the 10" slide rules I know about are actually 25 cm units sold as "10 inch" models. The L scale could be used as a measurement ruler in a pinch if you knew this fact. Also I think is is important to make clear that log x refers to base 10. Finally, slide rule use diminished gradually as computers became more common, not abruptly in the 1970's --agr 04:48, 27 February 2006 (UTC)
 * If a distance on a scale is proportional to the base-10 log of x, then it is also proportional (with a different proportionality constant!) to logarithm of x to any other base, is it not? How much ponderosity can we stand in one sentence? My impression of the decline was that it was rather abrupt -digital computers were scarce well past the 1950's, at least. Weren't the big atom-bomb calculations in the early 1940's done by rooms full of clerks on mechanical adding machines?  When I registered for university in 1977, the book store still sold slide rules, but they were completely gone a year or two later ( I still have a few I bought at clearance). --Wtshymanski 18:58, 27 February 2006 (UTC)
 * It's not that the distance is proportional to log10, it is log10, normalized to the length of the ruler. Thus the '8' mark on your slide rule will be exactly log10 (8) x 250 mm = 225.77 mm from the index.  The slide rule takes advantage of the unique property of the common log that the stuff to the left of the decimal merely tracks powers of ten and can be ignored. I agree that the sections in question are ponderous and need work, but this is an important fact to preserve.


 * As for the slide rule's demise, a lot happened between the 1940s and the 1970s. Computers were a very scarce resource in the mid-1950s but became much more available to technical workers during the 1960s. The introduction of Fortran in 1957 made computers practical for solving modest size mathematical problems. IBM introduce a series of more affordable computers, the IBM 650 (1954), IBM 1620 (1959), IBM 1130 (1965) addressed to the science and engineering market. John Kemeny's BASIC programming language (1964) made it easy for students to use computers. Wang Laboratories introduced desk-sized calculators starting in 1965. The PDP-8 minicomputer was introduced in 1965. Also computers changed the nature of calculation. Before them, there was a great emphasis on working the algebra to get expressions into the most computable form. Small terms were approximated or dropped. With computers and Fortran, complex formulas could simply be typed in from text books. Numerical integration was often easier than trying to find closed form solutions. More complex problems could be atacked. The young engineer asking for computer time to solve a problem that could be done by a few swipes on the slide rule became a humorous cliche. Many computer centers had a framed slide rule with a note "In case of emergency, break glass."  By the time the pocket scientific calculator was introduce in 1972, slide rules were mostly used in schools, where textbook and exam problems were designed to be solved on them. That market dried up quickly once scientific calculators became affordable.--agr 15:00, 28 February 2006 (UTC)

Tedious Explanation
I would like to explain the above "in case of emergency" line, since the punch line (such as it is) might not be obvious to many people. In many settings of the period (around 1950 +/- a few decades), small fire extinguishers would be available in case a fire broke out. Since easily available fire extinguishers would be subject to vandalism or inappropriate use, many of them were placed behind an easily broken pane of glass, the theory being that a person would be less likely to use it unless there was a pressing need. The wording "In case of emergency, break glass" would usually be printed on the glass.

Some computer centers had the same type of frame and warning with an abacus inside.

That said, I'm not sure if this information should be added to the article, since it doesn't directly address the uses of slide rules, and anyway, if a 'joke' has to be explained, it loses much of the humor.

I'd be happy to leave the explanation here in the talk page. If anyone thinks it should be added to the article itself, please be my guest. Bunthorne 05:30, 23 March 2006 (UTC)

Revised intro
I didn't think the term "calibrated" was right. "Divided" is more appropriate. Any better ideas?

The part about usage waning in the 1950s and 1960s contradicted everything I know about the booming and proliferation of American, European, and Japanese slide rule companies in those decades, and my own experience as a 1970 high-school graduate. Anybody have good references or data? Dicklyon 15:45, 29 April 2006 (UTC)

Dubious Assertions
I don't believe either of these assertions:


 * Pickett brand slide rules were the standard in the Apollo program; Pickett's slide rules of the era often included a NASA or Apollo logo to promote the fact... Pickett N600-MES (6 inch, magnifying cursor, "Eye-Saver" yellow) was standard equipment on all Apollo flights.


 * Another mechanical pocket calculator, the Curta a.k.a. "pepper grinder", was also popular among scientists.

A Pickett went on at least one Apollo flight, but that's about it, as far as I've heard.

And nobody I knew ever had a Curta. When I discovered them years later, I found that their popularity was within the car-rallye set, not scientists and engineers, who had more appropriate tools for their trade (desktop digital mechanical calculators, and slide rules). And the Curta was never "known as" "pepper grinder".

Unless someone defends them, I'll probably remove them. Dicklyon 15:56, 29 April 2006 (UTC)


 * See the SciAm ref on Keuffel and Esser. That article makes the above assertion about the Pickett rules, but it's a different article that talks about the Curta. Unless it can be proven that the SciAm people looked it up on Wikipedia, I'll return the info for now. --M1ss1ontomars2k4 | T | C | @ 05:35, 20 May 2006 (UTC)


 * The SciAm author, Clifford Stoll, is not a slide-rule historian; he came to two west-coast meetings of the Oughtred Society and picked up a few fun things to write about, but his article is full of errors, so it is not a credible source of this rumor, which has been bandied about long before the wikipedia. I'm taking it back out.  Dicklyon 17:18, 20 May 2006 (UTC)
 * Ok. I never put it back in anyway... --M1ss1ontomars2k4 | T | C | @ 18:14, 20 May 2006 (UTC)

I had an uncle who had and used a Curta; he was an actuary. htom OtterSmith 03:22, 20 June 2006 (UTC)


 * A Curta is not a slide rule, but for an actuary it's a better tool. Dicklyon 05:19, 20 June 2006 (UTC)


 * Another unlikely assertion: 'Keying in and rechecking with calculator is likely faster than rechecking with a slide rule.' I'm guessing this is on the same principle that calculators are faster than the abacus. ho humm. SirEelBiscuits (talk) 01:05, 19 May 2008 (UTC)

ST Scale
Some places, mention that the ST scale is used for Sine, Tangent, and conversion to radians. We might note that for slide rules with an S scale but no ST scale, (a Pickett 520, or example) the users would convert degrees to radians directly by dividing by 57.3 ('R' at 573 on C or D) and use the x = sin(x) = tan(x) approximation for x < 5.7 with less than 0.3% error. See for x=sin(x)= cos(x). 70.186.213.41 06:33, 14 September 2006 (UTC)


 * Thanks for pointing out that such a thing exists, in spite of my disbelief. Funny thing is, I actually have that one.  I'm still not convinced it needs to be said, since it's such a strange fluke, but I can't really object I guess. Dicklyon 06:45, 14 September 2006 (UTC)


 * For small x, x ~= sin x ~= tan x != cos x ; as x goes to 0, cosine goes to 1. --htom 03:42, 21 September 2006 (UTC)

CORDIC
I question the following addition:


 * An important step toward the replacement of slide rules with electronics was the introduction of the CORDIC (coordinate rotation digital computer) algorithm by by Jack E. Volder, which allows for calculation of trigonometric (sin, cos, tan) functions with only shift and add operations. This method allowed the replacement of the analog resolver in B-58 aircraft navigation computer by accurate digital electronic devices, and kicked off the development of scientific calculators. Such calculators, of which the Hewlett-Packard HP-9100 was the first, in 1968 featured trigonometric, exponential and logarithmic functions, like slide rules, and unlike the other calculators of that time.

I think it's a stretch to call it "an important step toward the replacement of slide rules with electronics." There were ways to compute transcendental functions on digital computers before 1959. Perhaps CORDIC made it easier to create scientific calculators, but so did other technologies such as LEDs and integrated circuits. The text seems more appropriate to the calculator article than this one. --agr 01:30, 2 January 2007 (UTC)


 * I agree it's a stretch. I added the CORDIC info back because it seemed important, but it wasn't the "nail in the coffin".  It's true that the CORDIC was used in early handheld calculators; certainly the HP-35, and that it's a lot more efficient than alternatives known at the time.  So take a turn at toning it down a bit? Dicklyon 05:37, 2 January 2007 (UTC)


 * I made a stab at doing that.--agr 20:00, 2 January 2007 (UTC)


 * Now if feels like you've practically reduced the winner to an also-ran. I think Wang's log approach was essentially a historical cul-de-sac, while the CORDIC revolutionized the calculator business.  I'll look for some sources... Dicklyon 20:33, 2 January 2007 (UTC)

Here's an interesting CORDIC source, though you need JSTOR access to get to more than the first page. The lower right figure reminds me that we ought to repair the figure in the CORDIC article to have right angles in the right places. Anyway, it says the CORDIC is used in "most pocket calculators". Dicklyon 20:41, 2 January 2007 (UTC)


 * This article is about slide rules, not calculators. To tell how slide rules were displaced by electronic calculators what's important is when they were introduced to the scientific and engineering market, not who had the better technology or who evetually prevailed. Wang was there first and had quite a business going for a while. Texas Instruments now owns the market, at least in education, and spreadsheet programs are probably more important than calculators in professional use. --agr 12:40, 3 January 2007 (UTC)


 * It would still be nice to have a correct record of how the electronic calculator industry took the market away from slide rules. The CORDIC has long been recognized as the relevant breakthrough that made it happen.  The Wang had no impact on the slide rule market, and the spreadsheet came along after the transition was complete. Dicklyon 17:03, 3 January 2007 (UTC)

Propose editable headings be removed. Let's Address the White Space
I haven't really processed the entry yet regarding style and content but I will say one thing I don't like. The article is broken into sections. It sounds ok but the results are big white spaces caused by hanging photos at the end of sections. If it were just one section, it would all blend in at those points. I say forget editable sections, it's not that big an entry and those large white spaces look amatuerish. —The preceding unsigned comment was added by Purple-foxglove (talk • contribs) 02:37, 2 January 2007 (UTC).


 * The article is much to long to do without standard section heads. I don't see the problem with the figures, but you can try messing with the placement to see if you can improve how it looks. Dicklyon 02:51, 2 January 2007 (UTC)

Ok we'll stick with what is. I din't work hard on this to have much say. Chris Redding

Really the only part is at the point between circular and cylindrical. Maybe one less circular photo--the white one maybe. It creates a white space. I moved watch photo to the left and the gap was reduced. Whatever you think. Chris

Pictures of slide rule
ISTM that these could be far clearer if they were created from scratch as a .svg or similar. Maybe someone who knows how to generate these from a short script can help out --Thenickdude 07:09, 30 January 2007 (UTC)

Missing circular slide rule picture
For some reason I can't figure out, the picture of the to-cursor circular slide rule disappeared yesterday. Was this intentional? It's copyright justification was that it is a photograph of the uploader's personal property. However, I'll be that the manufacturer, Pickett, thought it had a copyright on the design, so that may not be a sufficient justification. Fair use because it's depicting a historical object? (Can you still purchase these?) I have a different two-cursor circular that claims to be subject to a 1940 copyright, a picture of which I was going to upload until wondered about the potential copyright problem. Anoneditor 19:44, 11 March 2007 (UTC)
 * I removed simply because there were so many photos on the page that it was causing rendering errors. However, if you can find a way to reintroduce it without reintroducing the rendering errors, there's no particularly compelling reason not to.  Unfortunately, I wasn't able to find a good way to do it.  MrZaius  talk  19:50, 11 March 2007 (UTC)
 * Popped it back in under advantages. MrZaius  talk  19:57, 11 March 2007 (UTC)


 * Mr. Zaius: I think I've solved the problem with my last two edits. The content presents no problems on a 600 × 800 screen. "Advantages" was probably not the best place for it anyway. Anoneditor 04:50, 12 March 2007 (UTC)
 * Actually, there's a couple of good arguments to put it back into Advantages. Firstly, there are already two other images in the relatively short circular slide rule section, and, at a more common resolution of 1024x768 or a widescreen resolution, the images currently bleed over into the cylindrical slide rule section, pushing the cylindrical image almost entirely out of the section.  Secondly, as the advantages section is a list of reasons why people still find slide rules valuable, it makes sense to have an image of the most commonly purchased & used sort of slide rule, that being a circular slide rule used in avionics.  That said, if you still think it wouldn't work in Advantages, it would make a lot of sense to delete one of the two very similar-looking circular slide rule pictures.  There are no details in the pictures that so greatly differentiate the two that the general audience/novice/I can discern.  Note the similar thought expressed above by the user signing their posts "Chris."  MrZaius  talk  05:04, 12 March 2007 (UTC)


 * So, I cranked up my monitor resolution to 1024 x 768 and found no bleeding. It looks like this occurs at 1280 x 1024.  I wonder whether it makes sense to adopt a policy that all formatting should accommodate such a high screen resolution.  Nevertheless, I'll see if I can find a way to accomplish this.  As to deleting one of the images, I think the significance is that each shows a different method of implementing the circular rule, as my earlier edit explained.  If I were looking for a candidate for deletion (which I'm not), it would say the Breitling watch is sufficiently offbeat that it wouldn't do great harm if it's image weren't there.  Any comments on my concern for intellectual property in these photographs? Anoneditor 22:29, 12 March 2007 (UTC)

Circular slide rule accuracy
In his or her edit of June 12, 210.177.142.113 states that circular slide rules are less accurate than in-line slide rules because they are commonly manufactured with off center pivots. Though my own experience is anecdotal, I have never seen errors from this cause and so I am asking for a backup reference for this statement. Also, the meaning of "...a significant 0.2 mm offset at the diagonal scale point" is unclear to me. Would the author please explain this. Anoneditor 04:29, 12 June 2007 (UTC)

I have played with a Concise circular rule. I found scale alignment error due to off-centre. I have a Citizen slide rule watch which has the same error (due not to pivot but bezel.) I therefore conclude that the alignment of circular rules subject to off-centre error. Judging from the construction of the Concise, it is difficult to produce or to maintain centering precision of 0.1 mm. So I suggest such error being not-uncommon.

On a circular rule with a 0.1 mm off-centre towards 1.8D (for example), when C and D are aligned at 1.0D, the 0.1 mm offset at centre will be amplified by a factor of 2 (the distance ratio of diameter to radius) at 3.2D. Therefore the alignment error at 3.2D will be 0.2 mm. I have witnessed such error mechanism on my slide rule watch.

I have four straight rules and the worst of them have alignment error of some 0.15 mm. I found such error barely bearable so I suggest a 0.2 mm error being significant. 210.177.142.113 06:25, 12 June 2007 (UTC)

I have removed some subjective qualifier words, such as "not-uncommon" and "significant" from my earlier edit. 210.177.142.113 00:33, 13 June 2007 (UTC)


 * Thanks for your explanation. Also, I think your qualifier removal is appropriate. Anoneditor 02:48, 13 June 2007 (UTC)

Circa 1970 when I was in college, Edmund Scientific Supply used to sell a wristwatch featuring a stop watch and a circular slide rule for something like $15 -- which was a not-insignificant sum in that era. I bought one based upon the description. It turned out that the watch ran slow and required daily adjustment. The stop watch sweep hand could be started and stopped with a button, but not zero'd, so you had to stop it at zero manually (no easy task) or else do a mental subtraction to use it. It had these smaller 6-hour and 45-minute clockfaces whose hands moved in concert with the main hands, and thus seemed utterly useless. The slide rule was misaligned enough to cause serious errors. Finally, the "tick" was so loud, as I learned my first night with it on the nightstand, that I had to take it out of the room to get to sleep. Worst watch ever!! WHPratt (talk) 12:52, 9 April 2009 (UTC)

Popular culture: Heinlein
Almost all (or all) of Robert A. Heinlein's science fiction novels and short stories include references to slide rules (or slipsticks). Isn't it, as such, appropriate to mention this in the Popular culture section of the article? --Khokkanen 07:24, 29 September 2007 (UTC)
 * I'm a huge Heinlein fan, and you're right about the prominence of slide rules in his books. But no, I don't think it should be in the article.--76.167.77.165 (talk) 02:57, 20 June 2009 (UTC)
 * It might be appropriate to have a section or perhaps a new page to discuss the anachronisms of sliderules in classic sci-fi. Without going too much into WP:OR, there are many instances, such as the famous Have Spacesuit, Will Travel or the numerous mechanical computers in Asimov's works, of sci-fi authors not being very good at predicting the future.  Neuromancer not having cellphones would be another good example of this sort of anachronism that shows how the future is hard to predict. -- Autopilot (talk) 14:25, 27 June 2010 (UTC)

analog computer
am not really sure that the slide rule constitues an anolog computer, but i could be wrong. I was wondering if someone could explain why an abucus is not considred and analog computer, cause i have never heard of it being referred to as that, and isnt the slide rule similar to an abucus, as you can tell i have never used a slide rule sooooo lolTomasz Prochownik (talk) 08:04, 23 April 2008 (UTC)


 * No, an abacus is digital. Dicklyon (talk) 15:12, 23 April 2008 (UTC)


 * An abacus is digital because it stores numbers in a codification based in "packages". Beads can be either "up" or "down", and being "in-between" doesn't provide greater detail (i.e. you don't put a bead to the middle of the wire to represent a half). In continuous analog computers, on the contrary, a partial movement of pieces can represent a partial value - for example, if you move the Slide rule a bit past number 2 to calculate 2*5, the computed value will be a little bit higher than 10. Diego (talk) 15:52, 23 April 2008 (UTC)

ya but an abucus is not considered to be a digital computer, i mean that would most definately be stretchTomasz Prochownik (talk) 20:25, 23 April 2008 (UTC)


 * A slide rule is analog because it works by adding the lengths of scales, placed end to end. An abucus is digital because it works by symbol manipulation. I'm not sure either is a computer, they're both mechanical calculation devices. So is a Curta, which is very different than either. htom (talk) 22:17, 23 April 2008 (UTC)

am of the thinking that their not computers but the slide rule on this page is listed as an analog computer, so this whole thing has got me thinking about how far in history can we stretch the term computer, like what qualifies as a computer? Tomasz Prochownik (talk) 07:16, 24 April 2008 (UTC)


 * There was a time when "computer" was a job title, like "secretary" or "typist". They were people who were good at doing computations, using whatever tools were available at their time. The way the English language works, "general purpose electronic programmable digital computing machine" became "computer", leaving some old phrasings looking odd, although they're correct. I would not personally call an ordinary slide rule (straight or circular) a "computer", but I'd call an E-6B a flight computer. htom (talk) 16:23, 24 April 2008 (UTC)

but the whole point of my rabble here is that the slide rule is essentially listed as a computer on this page, an analog computerTomasz Prochownik (talk) 06:09, 25 April 2008 (UTC)


 * There are many definitions of "computer", and one of those is "an aid to making calculations". A mechanical analog aid to making computations is what it is. You have to let go of the idea that the only kind of computer is the general purpose programable electronic digital one; that's a very specific (and now very common) kind, but not the only kind. htom (talk) 14:07, 25 April 2008 (UTC)

When I started studying computer science in the 1970s, when few universities offered such a major, we learned about two types of electronic computers: analog and digital. The only thing we learned about analog computers was that we would not be studying them. Thus there was a formal definition within the field of computer science, but words have technical and lexical definitions. A computer, meaning a person who computes, had nothing to do with the technical definition and had fallen into general disuse in English. Nevertheless, it still fell under the lexical definition.

Slide rules are analog computing devices, and the abacus, to the extent of my practical knowledge and ability to use one, is what I'd consider a digital computer. That's not in the base 2 sense but in the base 10 sense. Plus I use my fingers to operate it and you can't get more digital than that. But I'm not sure how helpful it is to refer to a slide rule as anything beyond an analog computing device. Hagrinas (talk) 16:28, 25 October 2010 (UTC)

slip stick
Slipstick redirects here, but Slip-stick is also an alias for Stick-slip, so I wanted to make add a "disambig" line linking there; however when one comes here via "Slide rule", this might be confusing... any suggestions ? &mdash; MFH:Talk 16:48, 4 July 2008 (UTC)

Slip stick should then, I would think, become a disambiguation page, with three links, one to Slide Rule (comptation device), one to Stick-slip (friction), and one to Slap-stick (physical humor) for those who mis-heard the term? htom (talk) 17:53, 4 July 2008 (UTC)

Pickett Inc?
So, I am an amateur slide rule collector. Most of mine are Pickett model. So who is Pickett? Are they a company, did they make anything else? They seem prolific enough to be considered noteworthy by Wikipedia. Should I starts an article? :) Jesset77 (talk) 08:08, 27 August 2008 (UTC)


 * There is an article on Keuffel and Esser, so one on Pickett would be appropriate. Here is one source I found: http://www.sliderulemuseum.com/SR_Dates.htm (scrolldown to the Pickett section).--agr (talk) 10:46, 27 August 2008 (UTC)


 * Yes, Pickett needs a page. I'm trying to find where Pickett Square was in Santa Barbara from when it was there (I think just off State Street near where General Electric had its TEMPO think tank). It folded very fast, and I never found where it was while I was there.  74.95.195.137 (talk) 20:44, 6 November 2011 (UTC)

Aviation and the slide rule
The still common and near-mandatory use of slide rules by pilots, at least while training, for navigation exercises, crosswind calculations etc should be noted. I'll try and do that but, in the interim, anybody ... Paul Beardsell (talk) 01:28, 23 December 2008 (UTC)

Easily replicated?
A slide rule is an easily replicated technology. From a given example of a slide rule, more can be constructed by a competent craftsman from rudimentary materials using non-industrial processes. I really want to rephrase this. I don't even think the Professor on Gilligan's Island managed to make a slide rule - and he *had* access to unlimited quantities of bamboo. Dividing a scale into those tricky logarithmic increments is fairly high tech and I doubt a castaway would be able to make one, which is what this paragraph sounds like. Given an exemplar, unlimited time and labor, and the materials of the era, one could imagine a functional Pharonic recreation of an Underwood typewriter, though it probably wouldn't last as long. It wouldn't be easy, and replicating all those scales may not be as easy as this paragraph implies. I'm not sure what this paragraph is trying to say...everyone in the world has access to electronic calculators today, it's not like there's a technology embargo saying that some places have to make everything out of birch bark and spruce gum. --Wtshymanski (talk) 14:27, 6 February 2009 (UTC)
 * It reads "[F]rom a given example", and that's important. Thus a good carpenter could replicate a slide rule -- even if he wasn't a mathematician -- by carefully copying all the scales. WHPratt (talk) 12:58, 9 April 2009 (UTC)
 * Yeah, that part of the article strikes me as a little silly. Maybe if civilization collapses...--76.167.77.165 (talk) 02:58, 20 June 2009 (UTC)
 * I think you can make a slide rule from ordinary lined paper, with no special tools. Here are instructions suitable for children. The trick is not to divide things into tricky logarithmic increments, it's to assign an exponentially increasing numbers to equally spaced increments. I've heard that one can manufacture a slide rule to use on an exam that disallows calculators, by folding paper in half several times (to get a base-2 logarithmic scale), but I haven't tried this myself and can't find a web page. These improvised slide rules are probably fairly inaccurate, but they show it can be done. —Ben Kovitz (talk) 19:16, 27 July 2009 (UTC)

Prosthaphaeretic Slide Rule Pic
Wikipedia has a picture of a Prosthaphaeretic slide rule (mentioned in the "Modern Form" section). Given the relative recentness of the invention, and the relative obscurity of the device, it seems that including or linking such a picture would greatly aid user understanding of the device. -- 66.253.112.94 (talk) 02:56, 10 March 2009 (UTC)
 * It's not a slide rule! Linear scales, not logarithmic. Doesn't "slide" one scale against another.A cool gadget for educational purposes ( see http://www.eric.ed.gov/ERICWebPortal/custom/portlets/recordDetails/detailmini.jsp?_nfpb=true&_&ERICExtSearch_SearchValue_0=EJ720444&ERICExtSearch_SearchType_0=no&accno=EJ720444) but since it appears never to be used for practical calculations, it should not be over-emphasized in this article.--Wtshymanski (talk) 14:07, 10 March 2009 (UTC)

So-called "Advantages"
It seems to me that much of this article has a "pro"-slide rule vibe to it. That the nostalgia of some authors has led to the advantages of slide rules being significantly overplayed, out of what seems to me a perception that the ease and efficacy of using calculators and computers to do complex work has somehow cheapened the art of computation.

I think the first two advantages listed are completely specious. While some may be prone to believing their calculations have more significance than they do, the ability to NOT compute calculations to high significance, when merited, is clearly not an advantage. Both of these arguments seem to me paramount to declaring that cars were better before seatbelts, because then you REALLY had to be careful. At best these properties are ambiguous with respect to their advantageousness, so certainly cannot be called advantages with any encyclopedic responsibility.

And "slide rules are highly standardized"? Some advanced calculators may differ in higher level functions (graphing, algebra, etc.) but computations simple enough to be done on a slide rule are standardized across calculators as well.

Also: perhaps it should be filed under Disadvantages that slide rules require specialized and unintuitive instruction to use effectively (whereas calculators and computer algebra programs only require that the user be familiar with modern mathematical notation and syntax).

Interesting article on the whole, but the excessive slide rule love was getting to me by the end. The ONLY situation in which I can envision ANY advantage is the apocalypse, and even then I would think scavenging a TI-89 would be easier, and AAA batteries would surely be available in the burnt husks of department stores and the like. RWGPurcell (talk) 15:49, 22 July 2009 (UTC)
 * I agree with your analysis. *Forcing* the user to keep track of a computation is not an advantage over a device where it's *optional* to do it; in the second, the engineer can still take the same care, and the first one is more error prone. I'll be bold and make the change.Diego (talk) 16:29, 22 July 2009 (UTC)


 * You think you will be able to go out and find radiation hardened TI-89s? Or HP-48s? The "advantage" is that the engineer has to think about the computation, and not blindly agree with what the magic box says (the magic box, btw, has been known to be wrong!) htom (talk) 18:55, 22 July 2009 (UTC)


 * Why would the engineer blindly agree with a calculator more than with a slide rule? There's nothing that prevents the engineer to think about the computation when using a calculator, the same way that there's nothing forcing the engineer to take care when using a slide rule (which is what would make it an "advantage"). Anyway, a rule could be bent or distorted from heat, if you want to enter into that level of detail. Seriously, radiation-induced errors doesn't seem a reason to prefer a slide rule over an electronic calculator. Unless you're in a spaceship, that is. Diego (talk) 09:01, 23 July 2009 (UTC)


 * Radiation can destroy transistors (hence making the electronic calculator a paperweight; see electromagnetic pulse.) Heat would mostly expand a slide rule rather uniformly, and bending it to a non-circular shape (a straight line is a circle of infinite radius, in some ways) means it does not slide well. Typing the problem in as the parenthesized formula removes the intermediate results from the display; you're given the final answer, and are not even shown the catastrophic cancellation that occurred. The engineer has no opportunity to notice it, or any other error that might be occurring in the middle of the calculation. I used to teach slide rule; now I happily use a calculator for almost everything (and Mathematica for some things) but that does not mean that I don't know the risks of each. htom (talk) 17:19, 23 July 2009 (UTC)
 * Engineers were forced to take care when using a slide rule. All the slide rule did was provide the first three (or two and a half) significant digits of the answer. The engineer was responsible for tracking the order of magnitude manually. That became a usfull skill in itself. One learned to quickly estimate answers to complex problems in one's head. I wonder if young engineers have this skill today. --agr (talk) 03:11, 24 July 2009 (UTC)
 * I hope that those I've tutored were a selection from the bottom of the barrel -- but they were bright enough to know that they needed help! htom (talk) 03:24, 24 July 2009 (UTC)
 * My point is that engineers weren't forced to take care: they still could do calculations carelessly and make errors. A tool on itself can't decide the level of dedication that its user will have, so it's up to the engineer to devote the needed attention for its correct usage. Neither a slide rule nor electronic calculator will avoid that. The original redaction seemed to imply otherwise. Diego (talk) 08:03, 24 July 2009 (UTC)
 * Of course they were not "forced". The calculator and computer, though, do remove the intermediate results from inspection (both can usually be made to reveal them, though.) Human error is always going to be with us; I sometimes wonder if the reason that the I-35 bridge fell is that someone made an error in copying the thickness of the failed plates from one plate's dimensions to the next, and the drawing inspection didn't catch it. htom (talk) 20:41, 24 July 2009 (UTC)
 * I'm not sure what's the point you're trying to make. Are you suggesting slide rules show intermediate results in a way that calculators don't? Diego (talk) 08:23, 27 July 2009 (UTC)
 * Yes. The result of each step of the calculation using a slide rule is displayed for the user's (possible) inspection, just as if they were using a very old-fashioned (4-banger?) calculator; the modern algebraic calculator shows the formula and the results, but not (at least usually) the intermediate results of the chain of calculations. Errors in floating point arithmetic evaluation can be nasty and hard to see when you look at formulas; rearranging the formula's evaluation can produce different results. cf http://docs.sun.com/source/806-3568/ncg_goldberg.html -- just because the computer is in a little pocket-sized box doesn't make it immune to error. (slide rules are also floating point, just low precision.) htom (talk) 17:28, 27 July 2009 (UTC)
 * Concur. I use them myself for some types of ratio calculations because the picture of ratio relationships, for me, is more intuitive on a slide rule than on a calculator.  There is one class of problems, in fact, that is significantly more complex to solve on a calculator than on a slide rule, and that's the question of which set of integer proportions is closest to a given ratio.  (For example, which paper sizes are closest to the golden ratio 1:1.618..?  You can answer that in seconds on a slide rule.  This is probably one major reason why similar devices are still used by graphic designers.)  I can vouch for time-speed-distance calculations being much more intuitive on a slide rule as well, which is one reason the E-6B is still around as it does those types of calculations exactly the same way, just with the decade of the C/D scales wrapped around with a convenient marker at 60 and with an ETA scale that continues the minutes around for another decade into multiple hours.  The LL and S/ST/T scales, maybe not so much these days, I'll grant.  But I still keep a basic rule around for some things.  And I'm willing to make an LJ post about it if someone wants to use it as a reference for the [who?] in that section.  :D Lihan161051 (talk) 22:54, 14 January 2010 (UTC)


 * I agree with your analysis, RWGPurcell. As a first step toward fixing the article's slant toward slide-rule advocacy, I've just added the main disadvantage of slide rules: their high difficulty of learning and operation (when compared to calculators). Slide rules are beautiful and marvelous things, but let's not hide the main reason they were abandoned so quickly in the 1970s. The difficulty of learning and using a slide rule is of high importance to understanding their use and history, so the article should really flesh this out quite a bit more. BTW, my source, Clifford Stoll's article in Sci Am, also mentioned engineers using incorrect math in order to make calculations easier on the slide rule! (I added that, too.) —Ben Kovitz (talk) 04:36, 8 April 2011 (UTC)

20 inch slide rules
A quick Google search on ( "20 inch slide rule" -Wikipedia )gives a few score hits, showing that these things did exist and are of continuing interest to collectors. There'a few scholarly papers found by Google that use phrases like "calculations done on a 20 inch slide rule". Now, as to students keeping one for calculations - that's not so clear. Students are perennially broke and student calculations are not going to require extraordinary precision. 20 inch rules should be mentioned in the article, even if rare - perhaps not in the student context. I've never seen one, but I've read "Have Space Suit, Will Travel" which is an instance of "20 Inch Slide Rules in Popular Culture". --Wtshymanski (talk) 13:41, 30 October 2009 (UTC)
 * I've seen them in math and physics office display cases, never used one, and they were very rare even in the 1960s when I taught slide rule. A rich (or dedicated) student would have purchased a 10" basic plastic, then a 10" high-end, and then a 5" pocket rule. Maybe a circular rule instead of the 5", or in addition. Twenty inchers were things of legend, not reality. htom (talk) 16:12, 30 October 2009 (UTC)


 * A Google Books search turns up many contemporary references to 20-inch slide rules. From looking these over, I infer that although perhaps uncommon, they were widely available and certainly not "things of legend".  Some of the search results are slide rule catalogs.  For example, the W.E. Gurley company's "manual of surveying instruments" of 1912 includes a price list for slide rules; ten-inch rules are $3 and 20-inch rules are $12.50.  Thus they are expensive, but not prohibitively so.  But catalogs often describe 10 and 20-inch models as "student" and "engineer" models, respectively, so it seems that students were not the intended market for 20-inch rules.    —Dominus (talk) 17:35, 30 October 2009 (UTC)


 * I have more than a few in my collection of 600 slide rules; perhaps 3 or 4. I'd like to have more, but they're really uncommon.  I don't think I ever saw one in a store, back in the day.  Dicklyon (talk) 21:27, 30 October 2009 (UTC)


 * Note that the Sphere Slide Rule page classifies the 20" rules as "exotic" -- and I've seen more of King 66" helix rules than I have 20"(I didn't get to use those, either.) http://www.sphere.bc.ca/test/exotic.html htom (talk) 01:06, 31 October 2009 (UTC)


 * Same here. I have about 20 of the Otis Kings; they're relatively common and cheap compared to 20" rules.  Dicklyon (talk) 01:20, 31 October 2009 (UTC)
 * So can we add something like "For high-precision calculations, slide-rules were sometimes made with 20-inch scales." or am I going to get Wikiswarmed by and WP:NOR fact tags for this guarded generalization?  I do recall the 4 or 5 foot long slide rule that hung on one of my high-school classroom walls; but vauge recollection suggests it was scaled up for display purposes, not for precision. --Wtshymanski (talk) 16:30, 31 October 2009 (UTC)

<out We're talking, now, of two different things. One is the 20", higher accuracy, rule; the other is the five or six foot long, wall hanging, instruction rule (which was very precise if you kept it well lubricated and remembered to use only the left -- or right -- edge of the markings. Both could probably best be added to the "linear rules" section. I'm not sure whether to describe the 20" as "high precision" or "higher accuracy"; I suspect they were made to the same precision, but the longer length allowed for more accurate setting and reading. How about:

For more accuracy, some rules were made with 20" scales. Instructor's rules, five or six feet in length, were made with large markings that could be read from the back of the classroom.

htom (talk) 20:22, 31 October 2009 (UTC)


 * There zillions of books on slide rules, and some of them talk about approaches to getting higher accuracy, including longer straight rules, helical rules like the Otis King and Fuller, spirals like the Atlas, Thacher-type cylindricals, etc. Find a source and write it up; here are some.  Dicklyon (talk) 20:25, 31 October 2009 (UTC)
 * To heck with it then. I'll rack up edit count by reverting vandalism. There's no incentives to add content.  --Wtshymanski (talk) 23:07, 31 October 2009 (UTC)
 * What a bizarre comment. What kind of incentive are you looking for?  How about I give you nickel for every sourced fact you add that cites a new source?  Really, I'll be happy to; any article.  Up to $100/mo.  Bill me monthly.  Dicklyon (talk) 23:14, 31 October 2009 (UTC)
 * Realistically, how many people are going to be motivated by nickels? This is how much Wikipedia values content? I think that exactly illustrates the point. --Wtshymanski (talk) 13:56, 1 November 2009 (UTC)
 * My question was about the proper use of the words accuracy and precision in these contexts. Is a longer rule more accurate or more precise? It seems to me that it's likely the rules are made to the same precision (the error in the placement of marks being some small distance, say +-0.001 mm) regardless of the length, while the accuracy of the calculation increases with the length. Although it could be argued that the precision increases, too. htom (talk) 22:58, 31 October 2009 (UTC)
 * If you can read more decimal digits, it's more precise - if the slide isn't the same length as the body scale, then it will be inaccurate. --Wtshymanski (talk) 23:07, 31 October 2009 (UTC)
 * Depending on the skill and eyes of the user, my guess is that a 20" rule would give you about a half-digit more than a 10" (which gives a half-digit more than a 5".) Whether the progression is 2, 2.5, 3 or 2.5, 3, 3.5 is more in the user than the rule.htom (talk) 15:07, 1 November 2009 (UTC)


 * Doubling the length gives you one more bit at best (assuming that the relative precision of manufacturing also increases); that's less than 1/3 decimal digit. On the Otis King, the extra length is largely squandered due to imprecision in making the 66" scales. See my Flat Otis page, where I show that, for example, the mark for 4.63 is off by about 0.002, seriously messing up the potential 4-digit accuracy in that region.  Dicklyon (talk) 16:43, 1 November 2009 (UTC)


 * Not being a mathemetician, it took me until this morning to realize that this is wrong. If it was only 1 bit of precision, no-one would bother and no-one would mention that they used a 20 inch rule in their calculations. It's not X that gains the precision, it's log X. The number of decimal digits precision gained will vary depending on the "mantissa" of log X. Absolute scale errors are not as significant as relative scale errors - if the C and D scales have different lengths, that will damage accuracy, but as long as they grow and shrink together, it will cancel. Don't buy a slide rule where the pips for the C and D scales don't line up with "1" aligned on both scales.


 * I'm not sure what you're getting at. Doubling the length will increase the relative precision by a factor of two (1 bit) if the scales are perfect and the accuracy of reading is a fixed distance.  Dicklyon (talk) 18:03, 2 November 2009 (UTC)


 * User:Dicklyon, on the few 20 inch rules in your collection, do you recall if they are more finely divided than 10 inch rules? --Wtshymanski (talk) 14:16, 2 November 2009 (UTC)


 * Yes, they do have about twice as many tic marks; some 10" rules are also "finely divided" (e.g. K&E with an "F" appended the model number). Compare scale details here.  Dicklyon (talk) 18:36, 2 November 2009 (UTC)


 * Measuring a computer-manipulated scanned image of a slide rule scale seems a little indirect - I wouldn't trust the mechanism of my $89 Chinese-made flatbed scanner to be precise to the level required to claim that a tic mark is misplaced on a slide rule scale. How does one authenicate the accuracy of the scanning process? --Wtshymanski (talk) 14:22, 2 November 2009 (UTC)


 * It's a valid concern; it wouldn't be hard to test and calibrate the scanner; since they're based on linear CCDs and precision mechanical mechanisms, I'm sure they'll turn out to be plenty good to verify the local errors that I show there. But I'm not making any claims that this is rigorous, just a quick look at a an old scale that was made by hand.  Dicklyon (talk) 18:03, 2 November 2009 (UTC)

Building slide rules
My discussion of my program is not spam. My program is the *only* software ever written that generates gcode for a CNC milling machine to etch slide-rules. My program is also BSD-license, so I am not making any money on it or restricting anybody in any way.

All of the other programs written to construct slide-rules involve scanning an image of an old slide-rule into the computer and then printing out this image on to an adhesive label. My program does a recursive descent using a table of reduction values to generate the marks, and then converts this into gcode. There is nothing else like this. Why should Wikipedia be okay with including discussion of toy programs that are only useful for making cardboard slide-rules, but not be okay with a discussion of a program that can actually be used to build an aluminum slide-rule?

I agree that I am not the one to write the description, as I am obviously biased. Just to delete all reference to my program is not cool though. If anybody believes that my section was inaccurate in any way, then point out where it is inaccurate. Hugh Aguilar (talk) 22:46, 18 February 2010 (UTC)
 * Promoting your own product or original research is strictly against Wikipedia policy. Most of the text wasn't about slide rules. --Wtshymanski (talk) 22:56, 18 February 2010 (UTC)

My text was about slide-rules! You are not making any sense. As I said, I agree that it is inappropriate to promote my own software. Somebody else should write a description of my program. All you are doing is deleting all reference to my program though --- that is not a positive contribution. Hugh Aguilar (talk) 23:54, 18 February 2010 (UTC)
 * This isn't a debate. I put in an external link to your Web page.  We'll see if anyone else thinks that's too much promotion. --Wtshymanski (talk) 13:54, 19 February 2010 (UTC)