Copyright © Philip M. Parker, INSEAD. Terms of Use.
Definition: Slide Rule |
Slide RuleNoun1. Analog computer consisting of a handheld instrument used for rapid calculations; have been replaced by pocket calculators. Source: WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved. |
Synonym: Slide RuleSynonym: slipstick (n). (additional references) |
(From Wikipedia, the free Encyclopedia)
The slide rule is a mechanical precursor of the pocket calculator. It was invented in 1625 by William Oughtred.
Once widely used for rapid, approximate scientific and engineering calculations, a slide rule is an analog computer consisting of three interlocking calibrated strips. The central strip can be moved lengthways relative to the other two. A sliding cursor with an alignment line can record an intermediate result on any of the scales.
One slide rule remains in daily use around the world, the E-6B. This is a circular slide rule first created in the 1930s for pilots to help with dead-reckoning. It is still available in all flight shops, and remains widely used. While GPS has greatly reduced the use of dead-reckoning for aerial navigation, the E-6B remains widely used as a backup device and the majority of flight schools demand its use.
The scales are logarithmic. That is, a number x is printed on each rule at a distance c·log(x) from the 'index', which is marked with the number 1.
To multiply x by y, one aligns the index on the sliding scale with the number x on the fixed scale. To do this, the sliding scale must be moved over a distance of c·log(x). The number y on the sliding scale has now moved from its old position, c·log(y), to c·log(y)+c·log(x) = c·log(xy), and is therefore aligned with the number xy on the fixed scale.
For example, the illustration below shows the multiplication of 2 by 3.5. The index (1) on the upper scale is aligned with the 2 on the lower scale. The number 3.5 on the upper scale is aligned with the product, 7, on the lower scale.
Division reverses this process. The illustration below shows the division of 22 by 2.75. The index (1) on the upper scale is aligned with the 2.75 on the lower scale. The 22 on the lower scale (the mark just to the left of the 22.5 mark) is aligned with the quotient, 8, on the upper scale.
Slide rules calibrated on one side were called "simplex." Slide rules calibrated on both sides were called "duplex."
Typically two significant figures of precision were possible, with three being obtained by expert users who could estimate the fraction between gradations. Some high-end slide rules had magnifying cursors that basically doubled the accuracy, permitting a 10 inch slide rule to serve as well as a 20 inch.
Slide rules often have other mathematical functions encoded on other auxiliary scales. The most popular were trigonometric, usually sine and tangent, logarithm of logarithm (base 10) (for taking the log of a value on a multiplier scale), natural logarithm and exponential scales. Some rules included a pythagorean scale, to figure sides of traiangles, and a scale to figure circles.
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.
A number of tricks were used to get more convenience. Trigonometric scales were sometimes dual-labelled, in black and red, with complementary angles, the so-called "Darmstadt" style. Duplex slide rules often duplicated basic scales on the back. Scales were often "split" to get higher accuracy.
Circular slide rules had 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 10cm circular would have a maximum accuracy equal to a 30cm ordinary slide rule.
Circular slide rules were mechanically more rugged, smoother-moving and more precise than linear slide rules, because they depended on a single central bearing. The central pivot did not usually fall apart. The pivot also prevented scratching of the face and cursors. Only the most expensive linear slide rules had these features.
The highest accuracy scales were placed on the outer rings.
Rather than "split" scales, high-end circular rules used helical (snail-shell-shaped) scales for difficult things like log-of-log scales. One eight-inch premium circular rule had a 50 inch helical log-log scale!
Circular slide rules also eliminate "off-scale" calculations, because the scales were designed to "wrap around."
A real disadvantage of circular slide rules is that less-important scales are closer to the center, and have lower accuracies.
The main disadvantage of circular slide rules was just that they were not standard. Most students learned on the linear slide rules, and never switched.
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 aluminum 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 acrylics or polycarbonates sliding on teflon bearings.
Magnifying cursors can both help engineers with bad eyes, and 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 light scrubbing with steel-wool. For painted slide rules, and the faint of heart, use diluted commercial window-cleaning fluid and a soft cloth.Theory of operation
Materials
Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Slide rule."
| Context | Synonyms within Context (source: adapted from Roget's Thesaurus). |
Numeration | Abacus, logometer, slide rule, slipstick, tallies, Napier's bones, calculating machine, difference engine, suan-pan; adding machine; cash register; electronic calculator, calculator, computer; |
| Source: adapted from Roget's Thesaurus. | |
Crosswords: Slide Rule |
| English words defined with "slide rule": Sliding rule, sliding scale. (references) |
| Specialty definitions using "slide rule": baked-and-graphite inspector, belt weather kit ♦ CAUSTIC OPERATOR ♦ DRAFTER, AUTOMOTIVE DESIGN LAYOUT ♦ FINAL TESTER, FLIGHT-INFORMATION EXPEDITER, FURNACE-STOCK INSPECTOR ♦ GAMMA-FACILITIES OPERATOR, getter operator, getterer, GETTERING-FILAMENT-MACHINE OPERATOR, GREEN INSPECTOR ♦ INSPECTOR, PACKAGING MATERIALS ♦ laboratory technician ♦ MAT TESTER ♦ packaging inspector, PRODUCT TESTER, FIBERGLASS ♦ QUALITY TECHNICIAN, FIBERGLASS ♦ roving technician. (references) |
| Domain | Usage | |
Lyrics | Don't know what a slide rule is for (Wonderful World; performing artist: Herman's Hermits) | |
Clever | You are an engineer if you still own a slide rule and you know how to work it. (references; author: unknown) | |
Source: compiled by the editor from various references; see credits. | ||
| Domain | Title | ||
Books |
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Music |
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Source: compiled by the editor from various references; see credits. | |||
| Thumbnail | Description & Credit |  | Hand holding pencil over transistor, and slide rule. Credit: Library of Congress. |
Source: pictures compiled by the editor from various references; see picture credits. | |||
| The following statistics estimate the number of searches per day across the major English-language search engines as identified by various trade publications. Hyperlinks lead to commercial use of the expression at Amazon.com. |
| Expression | Frequency per Day |
slide rule | 138 |
| Source: compiled by the editor from various references; see credits. | |
| Language | Translations for "slide rule"; alternative meanings/domain in parentheses. | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Albanian | rigë llogaritëse (sliding rule). (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Arabic | مسطرة حاسبة, المسطرة المنزلقة. (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Bulgarian | логаритмична линийка (sliding rule). (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Czech | logaritmické pravítko. (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Danish | skydelaere (calliper, vernier), regnestok (calculating rule). (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Dutch | schuifmaat (calipers, calliper, roller gauge), rekenschuif (calculating rule), rekenliniaal (calculating rule), rekenlat (calculating rule). (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Finnish | laskuviivoitin. (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
French | règle calcul. (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
German | rechenschieber (atari). (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Greek | κανόνας υπολογισμού (calculating rule), λογαριθμικόσ κανόνασ, λογαριθμικός κανόνας (calculating rule). (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Hebrew | 'רר" (carriage, sledge), סר'ל חשוב. (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Hungarian | logarléc. (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Indonesian | baris (queue, ranks, verse). (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Italian | regolo calcolatore (calculating rule). (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Japanese Kanji | 計算尺 , 滑り尺 . (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Japanese Katakana | すべりじゃく, けいさ"じゃく. (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Pig Latin | ideslay uleray régua de cálculo (sliding-rule). (various references) riglã de calcul (sliding rule). (various references) логарифмическая линейка (sliding rule). (various references) tehnička računaljka, šiber. (various references) regla de calculo (calculating rule). (various references) räknesticka (slide-rule). (various references) sürgülü hesap cetveli (guess stick, slipstick), hesap cetveli (calculator, ready reckoner, tally-sheet). (various references) логаріфмічна лінійка (sliding rule). (various references) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Scrabble® Enable2K-Verified Anagrams | |
| Words within the letters "d-e-e-i-l-l-r-s-u" | |
-1 letter: duellers, leisured. | |
-2 letters: dellies, duelers, dueller, eluders, leisure, residue, resiled, sullied, ureides. | |
-3 letters: desire, diesel, drills, dueler, duelli, duller, ediles, eiders, elders, elides, eluder, eludes, idlers, leudes, lieder, relied, relies, resell, reside, resile, reused, rilled, rilles, sedile, seidel, seller, sidler, siller, slider, ureide. | |
-4 letters: deers, deils, deles, delis, dells, dills, dirls, drees, dries, drill. | |
| Words containing the letters "d-e-e-i-l-l-r-s-u" | |
+1 letter: surveilled, tellurides. | |
+2 letters: derailleurs, squirrelled. | |
+3 letters: underbellies, underselling. | |
+4 letters: deleteriously, supercollider. | |
+5 letters: demultiplexers, skullduggeries, supercolliders. | |
| Source: compiled by the editor from various references; see credits. SCRABBLE® is a registered trademark. All intellectual property rights in and to the game are owned in the U.S.A and Canada by Hasbro Inc., and throughout the rest of the world by J.W. Spear & Sons Limited of Maidenhead, Berkshire, England, a subsidiary of Mattel Inc. Mattel and Spear are not affiliated with Hasbro. | |
| 1. Definition 2. Synonyms 3. Crosswords 4. Usage: Modern | 5. Usage: Commercial 6. Images: Photo Album 7. Expressions: Internet 8. Translations: Modern | 9. Anagrams 10. Bibliography |
Copyright © Philip M. Parker, INSEAD. Terms of Use.
