Slide Rule

#REDIRECT slide rule

Slide rule

The slide rule is an analog computer, usually consisting of three interlocking calibrated strips and a sliding window, called the cursor. It was commonly used until the 1970s, when electronic calculators made it obsolete.
==Basic concepts== In its most basic form, the slide rule uses two logarithmic scales to allow multiplication and division, common operations that are time-consuming and error-prone when done on paper. The user determines the location of the decimal point in the result, based on mental estimation. In a calculation with steps involving addition, subtraction, multiplication and addition, the addition and subtraction steps are done on paper, not on the slide rule. In reality, even the most basic student slide rules have far more than two scales. Most consist of three linear strips of the same length, aligned in parallel and interlocked so that the central strip can be moved lengthways relative to the other two. The outer two strips are fixed so that their relative positions do not change. Some slide rules ("duplex" models) have scales on both sides of the rule and slide strip, others on one side of the outer strips and both sides of the slide strip, still others on one side only ("simplex" rules). A sliding cursor with one or more vertical alignment lines can record an intermediate result on any of the scales, and is also used to find corresponding points on scales that are not adjacent to each other. More complex slide rules allow other calculations, such as square roots, exponentials, logarithms, and trigonometric functions. In general, mathematical calculations are performed by aligning a mark on the sliding central strip with a mark on one of the fixed strips, and then observing the relative positions of other marks on the strips. ==Operation== ===Multiplication=== The figure below shows a simplified slide rule with two logarithmic scales. That is, a number

x

is printed on each rule at a distance proportional to

\log x

from the "index", which is marked with the number 1. A logarithm transforms the operations of multiplication and division to addition and subtraction thanks to the rules

\log(xy) = \log(x) + \log(y)

and

\log(x/y) = \log(x) - \log(y)

. Sliding the top scale rightward by a distance of

\log(x)

aligns each numeral

y

, at position

\log(y)

on the top scale, with the numeral at position

\log(x) + \log(y)

on the bottom scale. Since

\log(x) + \log(y) = \log(xy)

, this position on the bottom scale is marked with the numeral

xy

, the product of

x

and

y

. The illustration below shows the multiplication of 2 with any other number. The index (1) on the upper scale is aligned with the 2 on the lower scale. This shifts the entire upper scale rightward by

\log(2)

The numbers on the upper scale (multipliers) correspond with the multiplication on the lower scale. For example, the 3.5 on the upper scale is aligned with the product 7 on the lower scale, the 4 with the 8, and so on as in this diagram: Operations may go "off the scale." For example the diagram above shows that the slide rule has not positioned the 7 on the upper scale above any number on the lower scale, so it does not give any answer for

2 \times 7

. In such cases, the user may slide the upper scale to the left, effectively multiplying by 0.2 instead of by 2, as in the illustration below: Here the user of the slide rule must remember to adjust the decimal point appropriately to correct the final answer. We wanted to find

2 \times 7

, but instead we calculated

0.2 \times 7 = 1.4

. So the true answer is not 1.4 but 14. ===Division=== The illustration below demonstrates the computation of 5.5/2. The 2 on the top scale is placed over the 5.5 on the bottom scale. The 1 on the top scale lies above the quotient, 2.75. ===Other operations=== In addition to the logarithmic scales, some slide rules have other mathematical function (mathematics)s encoded on other auxiliary scales. The most popular were trigonometric function, usually sine and tangent, common logarithm (log10) (for taking the log of a value on a multiplier scale), natural logarithm (ln) and exponential function (''e^x'') scales. Some rules include a Pythagoras scale, to figure sides of triangles, and a scale to figure circles. Others feature scales for calculating hyperbolic functions. On linear rules, the scales and their labeling are highly standardized, with variation usually occurring only in terms of which scales are included and in what order:

A, B	two-decade logarithmic scales
C, D	single-decade logarithmic scales
K	three-decade logarithmic scale
CF,DF	versions of the C and D scales that start from pi rather than from unity
CI,DI,DIF	inverted scales, running from right to left
S	used for finding sines and cosines on the D scale
T	used for finding tangents on the D and DI scales
ST	used for sines and tangents of small angles
L	a linear scale, used along with the C and D scales for finding base-10 logarithms and powers of 10
LLn	a set of log-log scales, used for finding natural logarithms and exponentials

====Roots and powers==== There are single-decade (C and D), double-decade (A and B), and three-decade (K) scales. To compute

x^2

, for example, we can locate x on the D scale, and read its square on the A scale. Inverting this process allows square roots to be found, and similarly for the powers 3, 1/3, 2/3, and 3/2. Care must be taken when the base, x, is found in more than one place on its scale. For instance, there are two nines on the A scale, and to find the square root of nine, we must use the first one; using the second one gives the square root of 90. ====Trigonometry==== For angles between 5.7 and 90 degrees, sines are found by comparing the S scale with C or D. The S scale has a second set of angles (sometimes in a different color), which run in the opposite direction, and are used for cosines. Tangents are found by comparing the T scale with C, D, or, for angles greater than 45 degrees, CI. Sines and tangents of angles smaller than 5.7 degrees are found using the ST scale. Inverse trigonometric functions are found by reversing the process. ====Logarithms and exponentials==== Base-10 logarithms and exponentials are found using the L scale, which is linear. For base e, the LL scales are used. ==Physical design== ===Standard linear rules=== The length of the slide rule is quoted in terms of the length of the scales, not the length of the whole instrument. The most common high-end slide rules are 10-inch duplex rules, while student rules are often 10-inch simplex. Pocket rules are typically 5 inches. Typically the divisions mark a scale to a precision of two significant figures, and the user estimates the third figure. Some high-end slide rules have magnifying cursors that effectively double the accuracy, permitting a 10-inch slide rule to serve as well as a 20-inch. A number of tricks can be used to get more convenience. Trigonometric scales are sometimes dual-labelled, in black and red, with complementary angles, the so-called "Darmstadt" style. Duplex slide rules often duplicate some of the scales on the back. Scales are often "split" to get higher accuracy. Specialised slide rules were invented for various forms of engineering, business and banking. These often had common calculations directly expressed as special scales, for example loan calculations, optimal purchase quantities, or particular engineering equations. ===Circular slide rules=== Circular slide rules come in two basic types, one with two cursors, and another with a moveable disk and a cursor. The basic advantage of a circular slide rule is that the longest dimension was reduced by a factor of about 3 (i.e. by pi). For example, a 10 cm circular would have a maximum precision equal to a 30 centimetre ordinary slide rule. Circular slide rules also eliminate "off-scale" calculations, because the scales were designed to "wrap around". Circular slide rules are mechanically more rugged, smoother-moving and more precise than linear slide rules, because they depend on a single central bearing. The central pivot does not usually fall apart. The pivot also prevents scratching of the face and cursors. Only the most expensive linear slide rules have these features. The highest accuracy scales are placed on the outer rings. Rather than "split" scales, high-end circular rules use spiral scales for difficult things like log-of-log scales. One eight-inch premium circular rule had a 50 inch spiral log-log scale! certified_chronometer_wristwatch_with_circular_slide_rule.">Image:Breitling_Montbrillant.jpg|thumb|''Breitling Navitimer Montbrillant'': certified chronometer wristwatch with circular slide rule. One significant advantage of a circular slide rule is that it never has to be re-oriented when results are near 1.0—the rule is always on scale. Technically, a real disadvantage of circular slide rules is that less-important scales are closer to the center, and have lower precisions. Historically, the main disadvantage of circular slide rules was just that they were not standard. Most students learned slide rule use on the linear slide rules, and never found reasons to switch. In 1952, Switzerland watch company Breitling introduced a pilot's wristwatch with an integrated circular slide rule specialized for flight calculations: the Breitling Navitimer. The Navitimer circular rule, referred to by Breitling as a "navigation computer", featured airspeed, rate of climb/time of climb/descent, flight time, distance, and fuel consumption functions, as well as kilometer–nautical mile and gallon–litre fuel amount conversion functions. One slide rule remaining in daily use around the world is the E6B. This is a circular slide rule first created in the 1930s for aircraft aviators to help with dead reckoning. It is still available in all flight shops, and remains widely used. While global positioning system has reduced the use of dead reckoning for air navigation, the E6B remains widely used as a primary or backup device and the majority of flight schools demand its mastery to some degree. ===Materials=== Traditionally slide rules were made out of hard wood such as mahogany or boxwood with slides of glass and metal. In 1895, a Japanese firm started to make them from bamboo, which had the advantage of being less sensitive to temperature and humidity. These bamboo slide rules were introduced in Sweden in the fall of 1933 [http://runeberg.org/tektid/1933a/0348.html], and probably only a little earlier in Germany. The best older slide rules were made of bamboo, which is dimensionally stable, strong and naturally self-lubricating. They used scales of celluloid or plastic. Some were made of mahogany. Later slide rules were made of plastic, or aluminium painted with plastic. All premium slide rules had numbers and scales engraved, and then filled with paint or other resin. Painted or imprinted slide rules are inferior because the markings wear off. Early cursors were metal frames holding glass. Later cursors were Acryl group or polycarbonates sliding on teflon bearings. Magnifying cursors can help engineers with poor eyesight, and can also double the accuracy of a slide rule. Premium slide rules included clever catches so the rule would not fall apart by accident, and bumpers so that tossing the rule on the table would not scratch the scales or cursor. The recommended cleaning method for engraved markings is to scrub lightly with steel-wool. For painted slide rules, and the faint of heart, use diluted commercial window-cleaning fluid and a soft cloth. ==History== The slide rule was invented around 1620-1630, shortly after John Napier's publication of the concept of the logarithm. Edmund Gunter of Oxford developed a calculating device with a single logarithmic scale, which, used with additional measuring tools, could be used to multiply and divide. In 1630, William Oughtred of Cambridge invented a circular slide rule, and in 1632 he combined two Gunter rules, held together with the hands, to make a device that is recognizably the modern slide rule. Like his contemporary at Cambridge Isaac Newton, Oughtred taught his ideas privately to his students, but delayed in publishing them, and like Newton, he became involved in a vitriolic controversy over priority, with his one-time student Richard Delamain. Oughtred's ideas were only made public in publications of his student William Forster in 1632 and 1653. In 1722, Warner introduced the two- and three-decade scales, and in 1755 Everard included an inverted scale; a slide rule containing all of these scales is usually known as a "polyphase" rule. The more modern form was created in 1859 by French artillery lieutenant Am�d�e Mannheim, "who was fortunate in having his rule made by a firm of natinal reputation and in having it adopted by the French Artillery." It was around that time, as engineering became a recognized professional activity, that slide rules came into wide use in Europe. They did not become common in the United States until 1881, when Edwin Thacher introduced a cylindrical rule there. The duplex rule was invented by William Cox in 1891, and was produced by Keuffel and Esser Co. of New York., In World War II, bombardiers and navigators who required quick calculations often used specialized slide rules. One office of the US_Navy actually designed a generic slide rule "chassis" with an aluminium body and plastic cursor into which celluloid cards (printed on both sides) could be placed for special calculations. The process was invented to calculate range, fuel-use and altitude for aircraft, and then adapted to many other purposes. Throughout the 1950s and 1960s the slide rule, or "slipstick," 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 WWII 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. Some engineering students and engineers actually carried ten-inch slide rules in belt holsters, or kept a ten-or twenty-inch rule for precision work at home or the office while carrying a five-inch pocket slide rule around with them. All this came to an end in the 1970s, when the advent of miniaturised calculators made slide rules obsolete. The last nail in the coffin was the launch of ''scientific'' pocket calculators; i.e., models featuring trigonometric and logarithmic functions, of which the Hewlett-Packard HP-35 was the first, in 1972. In 2004, education researchers David B. Sher and Dean C. Nataro conceived a new type of slide rule based on ''prosthaphaeresis'', an algorithm for rapidly computing products that predates logarithms. There has been little practical interest in constructing one beyond the initial prototype, however. [http://www.findarticles.com/p/articles/mi_qa3950/is_200401/ai_n9372466] ==Advantages== * A slide rule tends to moderate the fallacy of "false precision" and significant figures. The typical precision available to a user of a slide rule is about three places of accuracy. This is in good correspondence with most data available for input to engineering formulas (such as the strength of materials, accurate to two or three places of precision, with a great amount—typically 1.5 or greater—of safety factor as an additional multiplier for error, variations in construction skill, and variability of materials). When a modern pocket calculator is used, the precision may be displayed to seven to ten places of accuracy while in reality, the results can never be of greater precision than the input data available. * A slide rule ''requires'' a continual estimation of the order of magnitude of the results. On a slide rule 1.5 × 30 (which equals 45) will show the same result as 1,500,000 × 0.03 (which equals 45,000). It is up to the engineer to continually determine the "reasonableness" of the results: something easily lost when a computer program or a calculator is used and numbers might be keyed in by a clerk not qualified to judge how reasonable those numbers might be. * When performing a sequence of multiplications or divisions by the same number, the answer can be often determined by merely glancing at the slide rule without any manipulation. For example, using the ruler pictured above, you can compute virtually any multiple of two just by looking, leaving your hands free. This can be especially useful when calculating percentages, e.g., for test scores. * An important calculation can be checked by doing it once on a slide rule, and once on an electronic calculator; because the two instruments are so different, there is little chance of making the same mistake twice. * A slide rule does not depend on batteries. * Slide rules, unlike electronic calculators, are highly standardized, so there is no need to relearn anything when switching to a different rule. ==Finding and collecting slide rules== For the reasons given above, some people still prefer a slide rule over an electronic calculator as a practical computing device. Many others keep their old slide rules out of a sense of nostalgia, or collect slide rules as a hobby. A popular model is the Keuffel & Esser ''Deci-Lon'', a premium scientific and engineering slide rule available both in a ten-inch "regular" (''Deci-Lon 10'') and a five-inch "pocket" (''Deci-Lon 5'') variant. Another prized American model is the eight-inch Scientific Instruments circular rule. Of European rules, Faber-Castell's high-end models are the most popular among collectors. Although there is a large supply of slide rules circulating on the market, specimens in good condition tend to be surprisingly expensive. Many rules found for sale on :Category:online auction websites are damaged or have missing parts, and the seller may not know enough to supply the relevant information. Replacement parts are scarce, and therefore expensive, and are generally only available for separate purchase on individual collectors' web sites. The Keuffel and Esser rules from the period up to about 1950 are particularly problematic, because the end-pieces on the cursors tend to break down chemically over time. In many cases, the most economical method for obtaining a working slide rule is to buy more than one of the same model, and combine their parts. ==Notes== # Resetting the slide is not the only way to handle multiplications that would result in off-scale results, such as

2\times7

; some other methods are: (1) Use the double-decade scales. (2) Use the folded scales. In this example, set the left 1 of C opposite the 2 of D. Move the cursor to 7 on CF, and read the result from DF. (3) Use the CI scale. Position the 7 on the CI scale above the 2 on the D scale, and then read the result off of the D scale, below the 1 on the CI scale. Since 1 occurs in two places on the CI scale, and one of them will always be on-scale. Method 1 is easy to understand, but entails a loss of precision. Method 3 has the advantage that the it only involves two scales. # There is more than one method for doing division. The method presented here has the advantage that the final result cannot be off-scale, because one has a choice of using the 1 at either end. # ''[http://www.mccoys-kecatalogs.com/K&EManuals/4081-3_1943/4081-3_1943.htm The Log-Log Duplex Decitrig Slide Rule No. 4081: A Manual]'', Keuffel & Esser, Kells, Kern, and Bland, 1943, p. 92. # ''The Polyphase Duplex Slide Rule, A Self-Teaching Manual'', Breckenridge, 1922, p.20. ==See also== *Abacus *Common logarithm *Logarithm *Timeline of computing *Counting rods *Mathematical tables *Napier's bones *Nomogram *E6B ==External links== *[http://www.hpmuseum.org/sliderul.htm Sliderule information at the Museum of HP Calculators] *[http://www.ee.ryerson.ca/~elf/ancient-comp/sliderule.pdf ''Make your own slide rule''] (portable document format) *[http://www.acespilotshop.com/pilot-supplies/flight-computers/micro_e6b.htm ASA Micro E-6B Flight Computer] – A specialized circular slide rule *[http://flightgadgets.com/ase6bmetflig.html ASA E-6B Metal Flight Computer] – Metal model of the E-6B *[http://solar.physics.montana.edu/kankel/math/csr.html ''Make your own'' circular ''slide rule''] *[http://www.sphere.bc.ca/test/sruniverse.html The Slide Rule Universe] – A comprehensive slide rule reference and buying/selling site **[http://www.sphere.bc.ca/test/howto.html How a slide rule works] **[http://www.sphere.bc.ca/test/pickett.html Pickett Slide Rules] *[http://www.breitling.com/en/models/navitimer/navitimer/ Breitling Navitimer info webpage] – Wristwatch with circular rule *[http://www.sagmilling.com/tools/sliderule/ Sag Milling's Online Sliderule] fully functional online version of a slide ruler. *[http://www.oughtred.org/ Oughtred Society Web Page] dedicated to preservation and history of slide rules *[http://www.sliderule.ca/ Eric's Slide Rule Site] -- information on buying slide rules, cleaning them, and other topics *[http://www.sliderules.clara.net/prices/models.htm prices of slide rules] -- a statistical analysis of prices at which various models of slide rules have been sold on ebay *[http://www.mccoys-kecatalogs.com/index.htm Clark McCoy] -- extensive information about K&E slide rules: catalogs, scanned manuals, and historical information about the various models Computation Mathematical tools Mechanical calculators

Slide rule

==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. ==The ''c'' in ''c'' log(''x'')== This page doesn't explain the "c" in c log(x). Obviously a constant, but what determines its value? : Any value of ''c'' will do. It is the distance between the two index marks, so it's determined by the length of the wooden sticks that the slide rule is printed on. - User:Dominus ==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. --User: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. --User: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. -- User: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 800×600 pixel displays (and with the falling prices on 15" LCD screens of 1024×768 resolution, and the related sharp price drop of CRTs, I suspect that even 800×600 will soon be a thing of the past including almost all budget installations). --User: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.--User: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. --User: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. -- User: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. --User: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. -- User: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(?). --User: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. --User: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. --User: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. --User:Bcrowell 15:14, 30 Apr 2005 (UTC) ::::I've posted at the Wikipedia:Help desk to see if anyone knows how to fix this. --User: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?--User: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?). --User: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.--User: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™. :-) 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. --User: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. --User: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 - User: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. User: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. User: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''? User:Markalexander100 05:56, 15 Aug 2004 (UTC) **Good suggestion. I have revised the intro. Anything else? User: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. - User: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. --User:Coneslayer 21:46, 2005 Mar 10 (UTC) **Never mind, I was thinking wrong. --User: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! -- User: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? User: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! --User:Madpilot 02:16, 13 Mar 2005 (UTC) == von Braun photo == I would like to have some comments on the :Image:6407244.jpg which is used in the Wernher von Braun about him -- I wonder if that is one of his slide rules being partly visible in the picture. Please comment at the photo's Image talk:6407244.jpg. --User:Wernher 15:39, 10 Dec 2004 (UTC)

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S

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Words begining with Slide_rule:

Slide_Rule
Slide_rule
Slide_rule
Slide_Rule:_Autobiography_of_an_Engineer
Slide_ruler
Slide_rules