K+E (Keuffel & Esser) Slide Rule Model Archive

Keuffel & Esser Co. Slide Rules

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Welcome To The Sphere Research Slide Rule Universe !
K+E, Slide Rules from one of America's premier manufacturers!

Sphere Research Corporation
3394 Sunnyside Rd.
West Kelowna, BC, Canada V1Z 2V4
Phone: +1 (250) 769-1834
FAX:+1 (250) 769-4106
A great source for test equipment, repairs, calibrations, useful metrology information, and of course, SLIDE RULES!

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K+E's 38th catalog frontpiece, CLICK for larger pic!

Mr. Kueffel and Mr. Esser, from recently recovered company archives, CLICK for bigger PIC!

Mr. Wilhelm (William) Keuffel (left)
and Mr. Hermann Esser (right),
CLICK for larger pic!

Archival photograph from recently discovered documents passed from K+E to Azon to Itellicoat at the dissolution of each company. From the 100th anniversary company memorial publication materials.

Visit Clark McCoy's K+E Catalog Site.

K+E 100th Anniversary Publication (1967)

CLICK to download the zipped 100year book, 20mb file!

CLICK to download the entire scanned 100 year anniversary publication.

There are 41 pages (including cover letter, and front/back book covers). Everything is in one ZIP archive (all high res-JPG files), approximately 20mb in total size.

Thanks to Ray Brohinsky, here's the 100 year book files compressed and turned into a smaller (13mb) PDF document:

CLICK to Download
100 Year Book in PDF
Format

K+E company timeline, CLICK to get full sized JPG file.

Page 36, showing K+E's corporate timeline versus major world events. CLICK for full size JPG file.

The day the slide rules arrived...

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slide rule designs...

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The Slide Rule Universe

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To go to the
Slide Rule Marketplace

An amazing tour with K+E from 1940.

Learn How to Operate a Slide Rule with a 1928 K+E Lesson

Keuffel & Esser Co. factories were based in Hoboken, New Jersey (USA), with offices in New York, Chicago, St. Louis, San Francisco, Detroit, and Montreal. Started in 1867, slide rules were only a very small part of K+E's product offering, which included everything from drafting paper to survey instruments and drafting aids. K+E held patents for a wide range of slide rule features, including improved cursor indicators, functions and scales, and the adjustable body mechanism. Caught by the huge market shift created by electronic calculators, CAD systems and laser surveying systems, which displaced all of their strong markets, K+E shrank dramatically after 1972.

Slide rules were never very profitable for K+E, and production and most inventory was gone by the mid-70's. K+E even sold some TI manufactured calculators for a brief period trying to capitalize on their existing customer base and industry knowledge. The final assets of K+E, mainly involving paper products, were sold to AZON in 1987, after several painful internal re-organizations. AZON also acquired the remaining assets of Hughes-Owens in 1988, and the POST Company in 1994, relating to it's principal business, which is drafting and reproduction paper and film. Only these paper products survived the shakeout in all these related businesses. Dietzgen still exists today, but like AZON, is mainly in the paper business, and itself was taken over by Intellicoat.

Most K+E slide rules were originally implemented in mahogany, with celluloid white scale overlays, engraved scales and glass cursors. People (especially on eBay) often mistakenly think the scales on older K+E rules are made of Ivory, but they are not, they are made of white celluloid. Later slide rules like the 4097 were made from Xylonite, and then (4181, Deci-lon and Doric series) from "Ivorite", a smooth, white, long wearing plastic (Cycolac/ABS). Xylonite was quite brittle, and not an ideal body material, Ivorite was much better, more rugged, whiter in color, and has very good sliding/lubricating properties. K+E rule scales were normally engraved (sorry, "engine divided") for long wearing life, and often filled in different colors to accent inverse scales. A few inexpensive rules like the plain wood body 4058, have an impressed/printed scale. Glass magnifying cursor indicators were available, and increased the settability and resolution of virtually any rule, often making a 10" rule the effective equivalent of a 20" version. Reference data for the K+E magnifiers is shown towards the end of the table.

Notes: It is somewhat unclear what the difference is between K+E slide rule numbers that have an "N" at the front, and those that do not. Catalogs do not clarify this, but according to Ed Chamberlain, it reflects subtle design differences in a scale or mechanical construction detail, with the N designation being the NEW version of the rule. This is only a partial clue, as many K+E rules, such as the venerable 4053 Mannheim rule, existed in many subtle variations of body, cursor and scale designs, but were not differentiated by any part number change (a highly confusing situation). This rule and many others were then finally re-named with a 68-series number confusing matters even worse for collectors. Note that PIckett (a competitor) also added N to the front of rule numbers to indcate new physical designs.

4081-3
Log Log Duplex
Deci-Trig

68-1100
Deci-Lon

4053-3
Polyphase

4088-3
Duplex Polyphase

"4000" series data here is from the 1936 K+E catalog and some later numbers from live examples, later "4100" series numbers and 68-rules are taken from live examples and a 1964 K+E brochure. The dash number on these "4000" series rules indicates the size of the rule (based on the same scale pattern), and is the SCALE LENGTH, not the over-all size of the rule itself. There was a brief period (50's) where K+E used a different numbering scheme beginning 90 (9081 for example) for DORIC brand Ivorite body rules but then changed back to 4100 series numbers. 68-rules have no dash to indicate length, but had different ordering part numbers for different cases (with or without pocket clip or other case styles), although the slide rule number itself was not changed, raising confusion to new levels for all involved.

Dating K+E slide rules is a complicated task, as serial numbers were recycled three times at K+E. Based on external clues from the body and cursor (although caution is needed there, as it may have been replaced), as well as case and manual details, and any copyright or patent dates, it is possible to place the rule within one of the three probable cycles. The copyright or patent date IS NOT the date of manufacture, and may be decades earlier than the real production date. Note that evidence from Deci-lon rules shows at least one additional cycle after the ones shown below, plus some random numbers after 1964. Considerable work was done to calculate these serial number cycles by Wayne Feely and Ed Chamberlain, and Ed's quick chart is provided here with permission to help you date your rules. Click on the chart to bring up a larger version! Note that Joe Soper identified many end of manufacture rules that had out of sequence parts, so rules made in the last year or so of production may have numbers that do not fit this chart.

Ed's dating chart, CLICK for bigger PIC!

Click for bigger Chart!

4000 Series Dash Numbers -1 = 5" scales -2 = 8" scales -3 =10" scales -5 =20" scales	Click to see the 68-xxxx Series Number Conversion Chart
Get Michael O'Leary's K+E model cross reference file HERE. Contains model info, equivalent numbers, and cursor/magnifier part numbers	Click to DOWNLOAD the K+E Cross-Reference Note: this is an Excel File!

K&E Model Number	Slide Rule Type	Size, Core Material	Scales Features	IMAGE LINKS (Back to Return)
4012	Thatcher's Calculating Instrument	18" cylinder Wood	20 angular segments No indicator, A, B, C See also this page Wood box	Click for Bigger Pic! Click for Another Pic!
4013	Thatcher's Calculating Instrument	18" cylinder Wood	20 angular segments 3 inch reading glass, A, B, C See also this page Wood box
4017	Sperry's Pocket Calculator	2 1/8" diameter, watch style Metal, Glass	4 scales duplex indicator unknown
4031S	Mannheim	5" Wood	A, [ B, C, ] D, rulers, improved glass indicator, leather case	shows extra cursor
N4035S	Mannheim	8" Wood	A, [ B, C, ] D, rulers, improved glass indicator, leather case
N4041	Mannheim	10" Wood	A, [ B, C, ] D, rulers, improved glass indicator,
N4041S	Mannheim	10" Wood	A, [ B, C, ] D, rulers, improved glass indicator, leather case
4045	Mannheim	16" Wood	A, [ B, C, ] D, rulers, improved glass indicator,
4045S	Mannheim	16" Wood	A, [ B, C, ] D, rulers, improved glass indicator, leather case
4051	Mannheim	20" Wood	A, [ B, C, ] D [ S, L. T ] on slide reverse, side rulers, improved glass indicator,	Partial with 4055 Below Rest of the 4051 Rule
4051S	Mannheim	20" Wood	A, [ B, C, ] D, rulers, improved glass indicator, leather case
4053-2S	Mannheim Polyphase	8" Wood	inch A, [ B, CI, C, ] D, K, cm [ S, L, T ] improved glass indicator, leather case
4053-3	Mannheim Polyphase	10" Wood	inch A, [ B, CI, C, ] D K (edge) [ S, L, T ] frameless plate glass indicator, Flap case Early production (no serial number), from 1920's or earlier	Click here for Bigger Pic Click here for Other Side Click here for Side Scale
(N)4053-3	Mannheim Polyphase	10" Wood	inch A, [ B, CI, C, ] D, K, cm [ S, L, T ] improved glass indicator,
4053-3S	Mannheim Polyphase	10" Wood	inch A, [ B, CI, C, ] D, K, cm [ S, L, T ] improved glass indicator, sewn leather case
4053-3F	Mannheim Polyphase	10" Wood	inch A, [ B, CI, C, ] D, K, cm [ S, L, T ] improved glass indicator, finer divisions
4053-3FS	Mannheim Polyphase	10" Wood	inch A, [ B, CI, C, ] D, K, cm [ S, L, T ] improved glass indicator, finer divisions, leather case
(N)4053-5	Mannheim Polyphase	20" Wood	inch A, [ B, CI, C, ] D, K, cm [ S, L, T ] improved glass indicator,	CLICK for BIGGER PIC CLICK for BIGGER PIC! CLICK for BACK CLICK for BIGGER PIC CLICK for BACK
4053-5S	Mannheim Polyphase	20" Wood	inch A, [ B, CI, C, ] D, K, cm [ S, L, T ] improved glass indicator, leather case
4055	Mannheim Favorite	10" Wood	A, [ B, C, ] D [ S, L, T ]	Click here for Bigger Pic Click here for Other Side
4056	Mannheim Favorite	10" Wood	A, [ B, C, ] D
4058	Mannheim Beginner's	10" Wood	A, [ B, C, ] D, plain wood, xylonite indicator
4058C	Mannheim Beginner's	10" Wood	A, [ B, C, ] D, plain wood, frameless (wood sided) indicator	Click here for Bigger Pic Click here for Other Side
4058W	Mannheim Beginner's	10" Wood	A, [ B, C, ] D, white finish, plain frame indicator

4070-3	Polyphase Duplex Trig	10" Wood	K, A, [ B, T, ST, S, ] D, DI & DF, [ CF, CIF, CI, C, ] D, L Improved glass indicator. Trig scales degrees, minutes.
4070-3S	Polyphase Duplex Trig	10" Wood	K, A, [ B, T, ST, S, ] D, DI & DF, [ CF, CIF, CI, C, ] D, L Improved glass indicator. Trig scales degrees, minutes. Sewed leather case.	Trig in minutes/seconds CLICK for BIGGER PIC CLICK for OTHER SIDE
4071-3	Polyphase Duplex DeciTrig	10" Wood	K, A, [ B, T, ST, S, ] D, DI & DF, [ CF, CIF, CI, C, ] D, L Improved glass indicator. Trig scales degrees, decimals.
4071-3S	Polyphase Duplex DeciTrig	10" Wood	K, A, [ B, T, ST, S, ] D, DI & DF, [ CF, CIF, CI, C, ] D, L Improved glass indicator. Trig scales degrees, decimals. Sewed leather case
4080-3	Log Log Duplex	10" Wood	LL0, LL00, A, [ B, T, ST, S, ] D, DI, K & L, LL1, DF, [ CF, CIF, CI, C, ] D, LL3, LL2 Improved glass indicator. Trig scales inches, seconds, degrees. Several scale variations produced.	TRIG in Minutes/Seconds! CLICK for bigger PIC CLICK for bigger PIC
4080-5	Log Log Duplex	20" Wood	LL0, LL00, A, [ B, T, ST, S, ] D, DI, K & L, LL1, DF, [ CF, CIF, CI, C, ] D, LL3, LL2 Improved glass indicator. Trig scales inches, seconds, degrees.
4081-3	Log Log Duplex Decitrig ©1947	10" Wood	LL0, L, K, A, [ B, T, SRT (or ST), S, ] D, DI, LL1 LL02, LL03, DF, [ CF, CIF, CI, C, ] D, LL3, LL2 Improved glass indicator. Trig scales decimal degrees. Many cosmetic variations.	Click for other side!
4081-3S	Log Log Duplex Decitrig ©1947	10" Wood	LL0, L, K, A, [ B, T, SRT (or ST), S, ] D, DI, LL1 LL02, LL03, DF, [ CF, CIF, CI, C, ] D, LL3, LL2 Improved glass indicator. Trig scales decimal degrees. Many cosmetic variations. Orange sewn leather case	CLICK for bigger PIC
4081-5	Log Log Duplex Decitrig ©1947	20" Wood	LL0, L, K, A, [ B, T, SRT, S, ] D, DI, LL1 LL02, LL03, DF, [ CF, CIF, CI, C, ] D, LL3, LL2 Improved glass indicator. Trig scales decimal degrees.
4083-3	Hyperbolic Log Log Duplex	10" Wood	Sh1, Sh2, Th, A, [ B, T, ST, S, ] D, DI, LL01, LL1 LL02, LL03, DF, [ CF, CIF, CI, C, ] D, LL3, LL2 Improved glass indicator. Hyperbolic Sine and Tangent Trig scales, used in the power industry.	HYPERBOLIC SCALES
N4083-3S	Hyperbolic Log Log Duplex	10" Wood	L, LL01, LL1, A, [ B, T, ST, S, ] D, Th, Sh1, Sh2, LL02, LL03, DF, [ CF, CIF, CI, C, ] D, LL3, LL2 Improved glass indicator. Hyperbolic Sine and Tangent Trig scales (numerous scale layout variations), used in the power industry. Orange sewn leather case	HYPERBOLIC SCALES CLICK for bigger PIC CLICK for bigger PIC
4088-1S	Polyphase Duplex	5" Wood	K, A, [ B, S, T, CI, ] D, L & DF, [ CF, CIF, C, ] D Frameless glass indicator, leather case
4088-2S	Polyphase Duplex	8" Wood	K, A, [ B, S, T, CI, ] D, L & DF, [ CF, CIF, C, ] D Improved glass indicator, leather case
4088-3	Polyphase Duplex	10" Wood	K, A, [ B, S, T, CI, ] D, L & DF, [ CF, CIF, C, ] D Improved glass indicator	CLICK for BIGGER PIC CLICK for OTHER SIDE
4088-3S	Polyphase Duplex	10" Wood	K, A, [ B, S, T, CI, ] D, L & DF, [ CF, CIF, C, ] D Improved glass indicator, leather case	Magnifier and fitted case! CLICK for BIGGER PIC CLICK for OTHER SIDE
4088-5	Polyphase Duplex	20" Wood	K, A, [ B, S, T, CI, ] D, L & DF, [ CF, CIF, C, ] D Improved glass indicator
4088-5S	Polyphase Duplex	20" Wood	K, A, [ B, S, T, CI, ] D, L & DF, [ CF, CIF, C, ] D Improved glass indicator, leather case
4090-3	Log Log Trig Duplex	10" Wood	LL0, A, [ B, K, CI, ] T, S1, S2 L, LL1, DF, [ CF, CIF, C, ] D, LL3, LL2 Improved glass indicator. Trig scales degrees and minutes.
4090-3S	Log Log Trig Duplex	10" Wood	LL0, A, [ B, K, CI, ] T, S1, S2 & L, LL1, DF, [ CF, CIF, C, ] D, LL3, LL2 Improved glass indicator, leather case. Trig scales degrees and minutes.
4091-3	Log Log Deci-Trig Duplex	10" Wood	LL0, A, [ B, K, CI, ] T, S1, S2 & L, LL1, DF, [ CF, CIF, C, ] D, LL3, LL2 Improved glass indicator,. Trig scales in degrees and decimals of degrees.
4091-3S	Log Log Deci-Trig Duplex	10" Wood	LL0, A, [ B, K, CI, ] T, S1, S2 L, LL1, DF, [ CF, CIF, C, ] D, LL3, LL2 Improved glass indicator, leather case. Trig scales in degrees and decimals of degrees.
4092-3	Log Log Duplex	10" Wood	LL0, A, [ B, S, T, C, ] LL3, LL2, LL1 & K, DF, [ CF, CIF, C, ] D, L Improved glass indicator.
4092-3S	Log Log Duplex	10" Wood	LL0, A, [ B, S, T, C, ] LL3, LL2, LL1 & K, DF, [ CF, CIF, C, ] D, L Improved glass indicator, leather case.
N4092-5	Log Log Duplex	20" Wood	LL0, A, [ B, S, T, C, ] LL3, LL2, LL1 & K, DF, [ CF, CIF, C, ] D, L Improved glass indicator.
N4092-5S	Log Log Duplex	20" Wood	LL0, A, [ B, S, T, C, ] LL3, LL2, LL1 & K, DF, [ CF, CIF, C, ] D, L Improved glass indicator, leather case.

4093-3	Log Log Vector Duplex	10" Wood	Sh1, Sh2, Th, [ SI1, SI2, TI, ] D, S, T & L, LL0, DF, [ CF, B, CI, C, D, ] LL3, LL2 Improved glass indicator, circular & hyperbolic functions.	CLICK for BIGGER PIC CLICK for OTHER SIDE
4093-3S	Log Log Vector Duplex	10" Wood	Sh1, Sh2, Th, [ SI1, SI2, TI, D, ] S, T & L, LL0, DF, [ CF, B, CI, C, ] D, LL3, LL2 Improved glass indicator, circular & hyperbolic functions, leather case.	Hyperbolic Scales! CLICK for BIGGER PIC CLICK for OTHER SIDE
4093-5	Log Log Vector Duplex	20" Wood	Sh1, Sh2, Th, [ SI1, SI2, TI, ] D, S, T & L, LL0, DF, [ CF, B, CI, C, ] D, LL3, LL2 Improved glass indicator, circular & hyperbolic functions.
4093-5S	Log Log Vector Duplex	20" Wood	Sh1, Sh2, Th, [ SI1, SI2, TI, ] D, S, T & L, LL0, DF, [ CF, B, CI, C, ] D, LL3, LL2 Improved glass indicator, circular & hyperbolic functions, leather case.
4094	Mannheim Merchant's	10" Wood	DF, [ CF, CI, C, ] D, rulers, improved glass indicator	Click here for Bigger Pic Click here for Other Side
4095-1S	Merchant's Duplex	5" Wood	DF, [ CF, C, ] D & [ CI, ] D frameless glass indicator, leather case
4095-3	Merchant's Duplex	10" Wood	DF, [ CF, C, ] D [ CI, ] D improved glass indicator.
4095-3S	Merchant's Duplex	10" Wood	DF, [ CF, C, ] D & [ CI, ] D improved glass indicator, leather case.
N4096	Mannheim Desk Slide Rule	20" Wood	DF, [CF, CI, C, ] D improved glass indicator, metal stands, leatherette covered hard case.
4097B	Mannheim Ever-There	5" Xylonite	DF, [ CF, CI, C, ] D & back rulers, improved glass indicator, very light weight, leather sheath.
4097C	Mannheim Ever-There	5" Xylonite	A, [ B, CI, C, ] D, K & [ S, L, T ] on reversible slide, back rulers, improved glass indicator, very light weight, leather sheath.	Large View
4097D	Mannheim Ever-There	5" Xylonite	A, DF, [ CF, CI, C, ] D, K & B, [ S, L, T ] on reversible slide, back cm/inch rulers, improved glass indicator, very light weight, leather sheath.
4098	Mannheim Pocket Slide Rule	5" Xylonite	A, [ B, C, ] D & [ S, L, T ] on reverse of slide, back rulers, frameless xylonite indicator, very light weight, leather sheath.
N4100	Mannheim Stadia	10" Wood	R, H, HC, V, A side ruler, A & B scales on reverse of slide, improved glass indicator, for survey work
N4100S	Mannheim Stadia	10" Wood	R, H, HC, V, A side ruler, A & B scales on reverse of slide, improved glass indicator, leather case, for survey work
N4101	Mannheim Stadia	20" Wood	R, H, HC, V, A side ruler, A & B scales on reverse of slide, improved glass indicator for survey work.
N4101S	Mannheim Stadia	20" Wood	R, H, HC, V, A side ruler, A & B scales on reverse of slide, improved glass indicator, leather case, for survey work.
N4102	Surveyor's Duplex	20" Wood	D, Sind, Coslah, C, Tan, Tan1, Az & Vert1, A, [ B, CI, C, ] D, Vert2 improved glass indicator, for surveying.
N4102S	Surveyor's Duplex	20" Wood	D, Sind, Coslah, C, Tan, Tan1, Az & Vert1, A, [ B, CI, C, ] D, Vert2 improved glass indicator, leather case, for surveying.
N4133S	Mannheim Roylance Electrical	8" Wood	A, [ B, CI, C, ] D, K & side ruler, side wire gauge, improved glass cursor, multiple hairlines, special rule marks, leather case.
N4135S	Power Computing Duplex	5" Wood	A, [ B, CI, C, ] D P, R, W, D, for steam, gas and oil engines, frameless glass indicator, leather sheath.
4139	Duplex Cooke Radio Rule	10" Wood	LC, A, [ B, T, ST, S, ] D, DI & L, DF, [ CF, CIF, CI, C, ] D, 2pi improved glass cursor, special electronics scales, hard case.

4150-1	Mannheim Pocket	5" Ivorite	DF, [ CF, CI, C, ] D, L blank on reversible slide improved plastic indicator, very light weight, leather sheath.
4153-1	Mannheim Pocket	5" Ivorite	A, [ B, CI, C, ] D, K [ S, L, T ] on reversible slide improved plastic indicator, very light weight, leather sheath.
4160	Chemist's Duplex	10" Wood	CI, [ D, Bought, ] Given & C, [ D, Bought, ] Given improved glass cursor, for chemical analysis.
4160S	Chemist's Duplex	10" Wood	CI, [ D, Sought ] Given & C, [ D, Bought, ] Given improved glass cursor, leather case, for chemical analysis.
4161-1	Mannheim Pocket	5" Ivorite	K, DF, [ CF, L, CI, C, ] D, A [ T, ST, S, ] C on reversible slide improved plastic indicator, very light weight, leather sheath.	CLICK for BIGGER PIC CLICK for BIGGER PIC CLICK for BIGGER PIC CLICK for BIGGER PIC
4161-3	Mannheim Slide Rule	10" Ivorite	K, DF, [ CF, L, CI, C, ] D, A & [ T, ST, S, ] C on reversible slide improved plastic indicator, very light weight, leatherette sheath.	CLICK for BIGGER PIC CLICK for BIGGER PIC
4168 also 68-1555	Duplex Doric	5" Ivorite	DF, [ CF, CI, C, D, ] L & K, A, [ B, ST, S, ] D, T improved glass indicator, leather sheath.
4175	Kurtz Psychometric	10" Wood	Special air conditioning scales, improved glass indicator, formulas on reverse.
4181-1	Log Log Duplex	5" Ivorite	LL02, LL03, DF, [ CF, CIF, CI, C, ] D, LL3, LL2 & LL01, L, K, A, [ B, T, SRT, S, ] D, DI, LL1 Improved cursor, leather case. See also 68-1287 for later release of the same rule. Note that several cosmetic variations exist, with all black, and black and red scales.	CLICK for bigger PIC! CLICK for OTHER SIDE!
4181-3	Log Log Duplex	10" Ivorite	LL02, LL03, DF, [ CF, CIF, CI, C, ] D, LL3, LL2 LL01, L, K, A, [ B, T, SRT, S, ] D, DI, LL1 Improved cursor, leather case. See also 68-1251 for later release of the same rule.	Large View
4185A	Magnifying Cursor	Glass	for 4031
4185B	Magnifying Cursor	Glass	for 4035-4088, 4094, 4095-3, 4096, 4100, 4101, 4133, 4165
4185C	Magnifying Cursor	Glass	for 4088-4093, 4095-5, N4096, 4102, 4142-4175

68-1100	Deci-Lon ©1947, 1961	10" Ivorite	Sq1, Sq2, DF, [ CF, CIF, L, CI, C, ] D, Ln0, Ln1, Ln2, Ln3 & Ln-3, Ln-2, Ln-1, Ln-0, A, [ B, T, SRT, S, C, ] D, DI, K Improved plastic cursor, leather case.	CLICK for BIGGER PIC CLICK for OTHER SIDE Front View Back View
-no number-	Deci-Lon ©1947, 1961	10" Ivorite	Sq1, Sq2, DF, [ CF, CIF, L, CI, C, ] D, Ln0, Ln1, Ln2, Ln3 & Ln-3, Ln-2, Ln-1, Ln-0, A, [ B, T, SRT, S, C, ] D, DI, K Improved plastic cursor, leather case. Final Deci-lon production, no model number or grip lines on slide.	CLICK for bigger PIC! CLICK for OTHER SIDE!
68-1130	Deci-Lon ©1947, 1961	5" Ivorite	Sq1, Sq2, DF, [ CF, CIF, L, CI, C, ] D, Ln0, Ln1, Ln2, Ln3 & Ln-3, Ln-2, Ln-1, Ln-0, A, [ B, T, SRT, S, C, ] D, DI, K Improved plastic cursor, pocket clip leather case. Pocket sized version of 68-1100 full size rule.	CLICK for BIGGER PIC CLICK for OTHER SIDE
68-1210	Log Log Duplex Deci-Trig	10" Wood	LL02, LL03, DF, [ CF, CIF, CI, C, ] D, LL3, LL2 & LL01, L, K, A, [ B, T, SRT, S, ] D, DI, LL1 Improved cursor, leather case. Appears to be a re-numbered 4081-3 rule.	CLICK for BIGGER PIC CLICK for OTHER SIDE
68-1215	Log Log Duplex Deci-Trig	10" Wood	LL02, LL03, DF, [ CF, CIF, CI, C, ] D, LL3, LL2 & LL01, L, K, A, [ B, T, SRT, S, ] D, DI, LL1 Improved cursor, leather case. Appears to be a re-numbered 4081-3 rule, complete with sewn leather case, in a set, the rule is still numbered 68-1210.
68-1251	Log Log Duplex Deci-Trig	10" Ivorite	LL02, LL03, DF, [ CF, CIF, CI, C, ] D, LL3, LL2 & LL01, L, K, A, [ B, T, SRT, S, ] D, DI, LL1 Improved cursor, leather case. Seems to be newly numbered 4181-3 rule in every respect.	CLICK for bigger PIC CLICK for OTHER SIDE
68-1287 68-1261 with leather clip case	Duplex Deci-Trig Jetlog Jr.	5" Ivorite	LL02, LL03, DF, [ CF, CIF, CI, C, ] D, LL3, LL2 & LL01, L, K, A, [ B, T, SRT, S, ] D, DI, LL1 Improved unbreakable cursor, leather case. Seems to be newly numbered 4181-1 rule in every respect.
68-1400 Analon	Analon engineering constant rule	10" Ivorite	V2, V1/2, A, [ B, U1/2, U-1, C, ] D, V, V-1 Improved unbreakable cursor, leather case, special manual. Completely unique rule and scale design, with pysical constants on the scales.
68-1497 4070-3 with decimal trig scales	Duplex Polyphase Duplex Deci-trig	5" Wood	Front - DF, [ CF, CIF, CI, C, ] D, L Back - K, A, [ B, T, SRT, S, ] D, DI improved unbreakable indicator, leather sheath.	Wood Edged Rule CLICK for BIGGER PIC CLICK for OTHER SIDE
68-1555 also 4168 68-1550 with leather clip case	Duplex Polyphase Duplex Deci-trig	5" Ivorite	DF, [ CF, CI, C, ] D, L & K, A, [ B, ST, S, ] D, T improved unbreakable indicator, leather sheath.
68-1565	GP12	10" Ivorite	Sq1, Sq2, DF, [ CF, T, SRT, S, CI, C, ] D, A, K & cm, inch rules, number to log converter, inch/cm converter. Conversion factors Senior Student slide rule plastic cursor, black and red scales, green plastic body supports, black leather case. Very nice but seldom seen late production rule.	CLICK for bigger PIC CLICK for OTHER SIDE
68-1586 68-1581 with leather clip case	Simplex Modern Polyphase	5" Ivorite	K, DF, [ CF, L, CI, C, ] D, A & [ T, ST, S, ] C improved unbreakable indicator, leather sheath.
68-1607 Same as 4053-5	Mannheim Polyphase	20" Wood	inch A, [ B, CI, C, ] D, K, cm [ S, L, T ] improved glass indicator, wood back. green leather flap case	CLICK for BIGGER PIC CLICK for BIGGER PIC! CLICK for BACK
68-1608 Same as 4053-5	Mannheim Polyphase	20" Wood	inch A, [ B, CI, C, ] D, K, cm [ S, L, T ] improved glass indicator, wood back. green leather flap case	CLICK for bigger PIC! CLICK for bigger PIC!
68-1617 Same as 4053-3S	Mannheim Polyphase	10" Wood	inch A, [ B, CI, C, ] D, K, cm [ S, L, T ] improved glass indicator, late production, Xylonite back. sewn leather case	Click here for Bigger Pic Click here for Other Side
68-1648 68-1643 with leather clip case	Simplex Polyphase	5" Ivorite	A, [ B, CI, C, ] D, K & [ S, L, T ] improved unbreakable indicator, leather sheath.
68-1749	Mannheim Desk Slide Rule	20" Wood	DF, [ CF, CI, C, ] D improved glass indicator, metal stands, leatherette covered hard case.
68-1791 68-1786 with leather clip case	Simplex Merchants	5" Ivorite	DF, [ CF, CI, C, ] D, L improved unbreakable indicator, leather sheath.
68-1892	K12 Prep	10" PVC	K, A, [ B, S, CI, T, C, ] D, L student slide rule plastic cursor, green scales, green plastic body supports, plastic pouch.
Mannheim rule	-	-	-
Mannheim rule	-	-	-
Old Pocket Mannheim rule	-	-	-shows extra magnifying cursor added.
Duplex rule	-	-	-
Duplex rule	-	-	-
Duplex rule	-	-	-

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Image credits: most of these images are from public postings to Ebay with no copyright restriction noted. I will be adding the exact references over time, so please be patient. If you are the originator of any image showm please advise, and we will add your specific credit and an email link (if desired). If you are the original owner, and do not want your image shown, please advsie, and we will remove it.

Many thanks, EMAIL

Walter Shawlee 2.

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