Chapter 7: My Portfolio of K&E Slide Rules

Before K&E built rules in-house, they outsourced their first slide rules, likely from the French maker Tavernier-Gravet.  No genuine Model 479 has ever resurfaced, so this un-badged T-G Mannheim rule in my collection — brass chisel indicator and all — is the best physical stand-in we have for what that first K&E-sold rule probably looked like, possibly as early as 1883.

I own this rule but haven’t written up its details yet — check back as this catalog grows.

The diminutive 5” pocket member of the 4041 Mannheim family.  My sample is missing its cursor, so finding a period-correct replacement could be a challenge.

The budget “Favorite” line sold alongside the flagship 4041 Mannheim, and the original boxwood versions of the 4054 and 4056 are genuinely hard to find, since most survivors in the wild are the later, more common mahogany Polyphase versions.  My 4054 sample dates to around 1915 and cost less than $20 — a keen-eyed bargain, since it’s easy to mistake for one of the ordinary later rules.  I also hold a bare, “polished” boxwood 4056, the even more budget of the two original Favorite models.

I own this rule but haven’t written up its details yet — check back as this catalog grows.

I own two 4058C samples from 1930–1935 — bare wood with printed scales and a glass cursor on wooden rails — which still function beautifully 90 years on; in my opinion, this is the version K&E should have made all along.  I also hold several 4058W samples from the 1940s–50s, and those have fared far worse: the white-painted wood is soft enough to dent with a fingernail, and most of mine have warped into unusability.  Between the two, it’s a small case study in how K&E’s budget “Student’s” line quietly declined in wood quality over the decades.

I own this rule but haven’t written up its details yet — check back as this catalog grows.

I own this rule but haven’t written up its details yet — check back as this catalog grows.

I own this rule but haven’t written up its details yet — check back as this catalog grows.

A thin, all-Xylonite pocket Mannheim rule that became K&E’s cheapest slide rule after the 4058 Student’s line, priced at $1.75 when it split off from the Ever-There series in 1936.  My sample carries black-only ink, which — cross-referenced against other known serial numbers — helps date the switch away from red-and-black printing to around 1940.  It was the last true Mannheim-scale rule left in the K&E lineup by the time it was discontinued in 1953.

The 4053 Polyphase Mannheim was K&E’s least-changed model over its entire run — essentially a 4041 with a K scale and a CI scale added — and one of their most enduring products, produced continuously from 1909 all the way to 1975 in one form or another.  I’ve collected the family across its three principal lengths, shown here side by side: the 8” N4053-2, the standard 10” rule, and the full 20” version.

The fine-divided option of the standard 4053, “divided as finely as the 20” rule,” at a $3.50 premium — produced between 1911 and 1943 but rare, since most buyers were happy with the standard division.  My sample dates to 1914, very early in the option’s run.

Made By

K&E

Style

Single-sided, Mannheim-type

Scale Length

10"

Purpose

General Mathematics

# of Scales

13

Country

USA

Material

Celluloid-covered mahogany

Date

1914

Production Number

721

Condition

C5

Front

Inches || A [B, CI, C] D || K

Back of Slide

[S, T, L]

Not to be confused with the early boxwood “Favorite” 4054 above — this is the later, more common all-mahogany version, reinstated in 1944 as a budget option alongside the N4053 Polyphase Mannheim.  I own this rule but haven’t written up its details yet — check back as this catalog grows.

One of K&E’s unnumbered “Mystery” rules — a university-market slide rule built on the “Improved Polyphase Mannheim” scale set, sold without any catalog model number.  Unlike the university-branded mystery rules also known among collectors, my sample has “decimal keeping” instructions printed on the back instead of a university insignia, placing it among what collectors call “Decimal Keeping Mystery rules.” Mine carries a 1937 serial number.

Front

Inches // A, DF [CF, CI, C] D, K \ Centimeters

Back of Slide

[S, B, L, T]

Date / Serial

1937

I own this rule but haven’t written up its details yet — check back as this catalog grows.

I own this rule but haven’t written up its details yet — check back as this catalog grows.

The all-plastic “Modern Polyphase” evolution of the 4053, considered the spiritual successor to the classic wooden rule at a heavy discount, with an ST scale in decimal degrees.  My sample dates to 1954.

Made By

K&E

Scale Length

10"

Purpose

General Mathematics

# of Scales

12

Country

USA

Material

Ivorite (all-plastic)

Date / Serial

1954 (SN 001480)

Condition

C3

Front

Inches || K, DF [CF, L, CI, C] D, A || Centimeter

Back of Slide

[T, ST, S, C]

The 5” pocket sibling of the 4161-3 above.  I own this rule but haven’t written up its details yet — check back as this catalog grows.

A 5” Polyphase Duplex, part of K&E’s original duplex-format lineup.

Scale Length

5"

Purpose

General mathematics

# of Scales

13

Country

USA

Material

Celluloid-covered mahogany

Dates / Serials

1924 (SN 106311), 1924 (SN 106624)

Front

DF [CF, CIF, C] D

Rear

K, A [B, S, T, CI] D, L

The 10” member of the Polyphase Duplex family, distinct from the 5” 4088-1 above.  I own this rule but haven’t written up its details yet — check back as this catalog grows.

The 20” member of the Polyphase Duplex family, distinct from the 5” 4088-1 above.  I own this rule but haven’t written up its details yet — check back as this catalog grows.

I own this rule but haven’t written up its details yet — check back as this catalog grows.

A genuinely rare plastic Doric-family rule, never described in an actual K&E catalog — only in a 1949 parts list — and likely produced for just two or three years around 1947–1949.  I picked this one up in 2023; it typically runs about $25 when it shows up at all, though good samples have become harder to find in recent years.  I haven’t photographed my own sample yet — check back as this catalog grows.

One of the small run of “Doric” plastic rules K&E briefly badged with a 9XXX model number starting around 1948 — this little 5” pocket duplex outlived every other Doric model, carrying the Doric name all the way to the end of the slide rule era in 1975.

Made By

K&E

Scale Length

5"

Purpose

General Mathematics

# of Scales

13

Country

USA

Material

Celluloid-covered mahogany

Date / Serial

1951 (SN 001463)

Condition

C4

Front

DF [C, CF, CI, C] D, L

Rear

K, A [B, ST, S] D, T

A one-year-only (1968) variant of the same 9068/4168 pocket duplex, made from green “Celcon” acetal co-polymer resin for the Celanese Company — reportedly the first commercial use of Celcon in a product.

Made For

Celanese, by K&E

Scale Length

5"

Purpose

General Mathematics

# of Scales

13

Country

USA

Material

Celcon resin (made by Celanese)

Date / Serial

1968 (SN 007000)

Condition

C2

Front

DF [C, CF, CI, C] D, L

Rear

K, A [B, ST, S] D, T

The Doric-era Merchant’s pocket rule (formerly the 9050-1) — very few known samples exist.  I still need to re-photograph and re-record proper stats for my own sample; the entry I had for it turned out to be data from an unrelated rule, copied over by mistake.

I own four samples spanning the evolution of K&E’s first flagship duplex rule: two “original” 4092s from around 1920, before the dash-suffix length designation existed, and two 4092-3s from 1933 and 1934, made after K&E switched to a sans-serif font and fully laminated edges in 1927.  The later pair are among my favorite slide rules to actually use — the 4cm-wide body and uncluttered scale arrangement of this family just feel right in the hands.

The 20” member of the 4092 Log Log Duplex family, distinct from the original/4092-3 samples above.  I own this rule but haven’t written up its details yet — check back as this catalog grows.

A 10” Log Log Duplex Trig from the short-lived 1933–1937 trig-scale redesign.  I photographed mine alongside my 4088-1 (above) as a cautionary example of celluloid edge lamination failing over time — likely part of why K&E abandoned full-edge lamination for inlaid celluloid strips in 1952.

K&E’s most successful duplex line, often called the standard-bearer of general-purpose slide rules.  I own a matched 20” Trig/Deci-Trig pair (pictured) as well as an additional 10” set, useful for visually demonstrating the only real difference between the two: how finely the trig scales are divided — sixths of a degree on the Trig, tenths on the Deci-Trig.

A full plastic Doric conversion of the flagship Log Log Duplex Deci-Trig scale set, offered in 1948 as a lower-cost alternative to the mahogany 4081-3. I’m still hunting for the 9071-3 and 9061-1 to round out the full known Doric family.

The hyperbolic-trig “Vector” duplex rule, born from a patent-royalty dispute with Louis Weinbach that’s a story unto itself.  I hold a 10” sample from just before the 1952 move to inlaid celluloid edges, and a 20” sample from around 1962 — enough of a spread to see the 1954 scale revision and 1955 SRT-scale relabeling play out across my own rules.

The all-plastic “Ivorite” successor to the flagship wooden 4081-3 Log Log Duplex Deci-Trig, later marketed as the “Jet-Log.” I own samples of both this and its Doric-labeled N9081-3 predecessor, and comparing them side by side is telling: the N9081-3 is heavier, stiffer, glossier, more square, and more purely white, while the 4181-3 is lighter, thinner, more beveled, and a slightly different shade — evidence of K&E refining the plastic formula between the two.

The pocket version of the 10” Model 4181-3, and in many ways the more successful of the two — as a pocket rule, it’s just really good.  Its scale set matched the full-sized rule, making it the most powerful pocket slide rule on the market at its 1953 introduction, regardless of maker.  From 1960 it was marketed as the “Jet-Log Jr.” (the 10” version becoming simply the “Jet-Log”), and both outlasted the wooden 4080/4081 legacy rules, remaining in the catalog through 1972.

Made By

K&E

Scale Length

5"

Purpose

General Mathematics

# of Scales

20

Country

USA

Material

Ivorite (all-plastic)

Dates / Serials

undetermined (SN 193281), undetermined (SN 003427)

Front

LL02, LL03, DF [CF, CIF, CI, C] D, LL3, LL2

Rear

LL01, L, K, A [B, T, SRT, S] D, DI, LL1

A curious “simplex” rule — duplex construction with plastic end brackets, but printed for one-sided use — whose back doubles as both a log-scale calculator and an inch/centimeter ruler.  At $6.50 in 1968, it struck me as a lot of capability for the price when I first came across mine.

Widely considered — by me included — the best general-purpose slide rule K&E ever made: 26 scales on an angular, all-Ivorite duplex body.  I own seven samples, never having paid more than $30 for any of them, which has let me track a running production change in the slide’s tongue-and-groove joint that determines whether the slide can be flipped end-for-end.

The pocket sibling of the Deci-Lon 10, and quite possibly the best pocket slide rule ever made — futuristic-looking, full of irony given it’s also one of the last rules K&E ever produced.  I hold two dated samples (serial numbers 011482 and 021968) that happen to bracket a running change to the slide’s joint, letting me pin down roughly when K&E stopped allowing the slide to be inverted.

Scale Length

5"

Purpose

General Mathematics

# of Scales

26

Country

USA

Material

Ivorite all-plastic (ABS); unbreakable indicator

Dates / Serials

1967 (SN 011482), 1967 (SN 021968)

Front

Sq1, Sq2, DF [CF, CIF, L, CI, C] D, Ln0, Ln1, Ln2, Ln3

Rear

Ln-3, Ln-2, Ln-1, Ln-0, A [B, T, SRT, S, C] D, DI, K

Two takes on the same simplified Merchant’s scale set — multiplication, division, and proportions only, aimed at businessmen and accountants rather than engineers.  The 4094 is a standard single-sided Mannheim build; the 4095-3 puts the same idea in duplex form, trading its front CI scale for a mostly blank back panel that K&E left open for owners to mark their own gauge points.

A hand-held version of K&E’s 20” Merchant’s desk rule, introduced in 1939 minus the desk model’s metal stands and slide knob.  My sample carries a 1938 serial number — a year before its official May 1938 price-list debut — which is a good reminder that a rule’s first catalog appearance isn’t always a reliable production date.

Part of K&E’s longest-running product line, distinct from the 20” N4101 above.  I own this rule but haven’t written up its details yet — check back as this catalog grows.

Part of K&E’s longest-running product line (1901–1960 in various forms), this 20” single-sided stadia rule of mine dates to 1943 and still carries a U.S. Geological Survey asset sticker on the back — a small, documented piece of wartime federal surveying history, and one I stumbled onto in near-mint condition with its original case.

Scale Length

20"

Purpose

Stadia Surveying

# of Scales

7

Country

USA

Material

Celluloid-covered mahogany; single-sided

Date / Serial

1943 (SN 964789)

Condition

C1 (all mint) — no box or documents

Front

Inches // R [H, HC, V] A \\ Centimeters

Rear Slide

[B, C]

Extras

Orange leather case (S-version)

Notes

Inventory tag — US Geological Survey #W-200092

The 1925 upgrade of the 4100 Stadia Rule above, adding an HC scale and later converting to semi-plastic construction in 1956.  I own this rule but haven’t written up its details yet — check back as this catalog grows.

The all-plastic spiritual successor to the Model 4100 Stadia, named for Princeton surveying professor Phillip Kissam, trading general-math capability on the back of the slide for an expanded R1/R2 scale set.  My sample still has its slide, plastic instructional insert, and case intact, right down to the maker’s marks in the slide well.

Made By

K&E

Scale Length

10"

Purpose

Stadia Surveying

# of Scales

5

Country

USA

Material

Ivorite (all-plastic)

Date / Serial

1960 (SN 396407)

Condition

C3

Front

Inches || R1 [V1/H/V3, HC, V2] R2 || Centimeters

I own this rule but haven’t written up its details yet — check back as this catalog grows.

A 20” duplex rule unique for pairing traditional stadia-reduction scales with astrometric scales for computing true north from a solar transit observation.  My 1937-dated sample was an auction find for under $100 — well below the $400+ this rule usually commands on eBay — with a cracked cursor rail repaired with cyanoacrylate glue, a common failure of rules from that era.

Scale Length

20"

Purpose

Stadia Surveying

# of Scales

15

Country

USA

Material

Celluloid-covered mahogany; metal end brackets

Date / Serial

1937 (SN 598125)

Condition

C5

Front

D, sin d [cos²α & h, C, tan] tan I, Az

Rear

VERT (½ sin 2α), A [B, CI, C] D, VERT (½ sin 2α)/HOR (cos²α)

An 8” single-sided rule for electrical infrastructure work, built on the 4035 Mannheim frame with a Brown & Sharpe wire-gauge scale and a distinctive three-hairline cursor for direct circle-area computation.  My sample has an unusual back-of-bottom-stator celluloid centimeter strip — as far as I know, the only known instance of that feature on a single-sided wooden Mannheim rule.

Made By

K&E

Scale Length

8"

Purpose

Electrical

# of Scales

13

Country

USA

Material

Celluloid-covered mahogany

Date / Serial

1924 (SN 75755)

Condition

C5

Front

Inches || A [B, C] D || B&S Gauge

Back of Slide

[S, L, T]

Back of Rule

Centimeters

Slide Well

Amp carrying capacity

Extra

Wire temperature in red on the B scale; 748 gauge mark for Watts/HP on the C scale; double hairline cursor

A rare, never-cataloged rule built on the 4081 Log Log Duplex Deci-Trig with an added “F” (frequency) scale for reactance calculations, believed to have been developed for the U.S. Naval Academy.  My sample is the second, post-1939 variant, and its serial number dates it to 1941.

Made For

US Naval Academy, by K&E

Style

Double-sided, duplex type

Scale Length

10"

Purpose

Radio Engineering

# of Scales

20

Country

USA

Material

Celluloid-covered mahogany

Date / Serial

1941 (SN 834375)

Condition

C5

Front

L, LL1, DF [CF, CIF, CI, C] D, LL3, LL2

Rear

LL0, LL00, A [B, T, ST, S] D, DI, F

K&E’s longest-enduring electronics rule, designed by Navy Chief Radio Electrician Nelson Cooke.  I own three samples spanning nearly the rule’s full production run: an early one with an unusually early 1938 serial number, this 1954 example (pictured), showing the later exposed-mahogany-edge construction and rounded “Cooke Radio” emblem, and a third from 1959.

Made By

K&E

Scale Length

10"

Purpose

Radio/Electrical Engineering

# of Scales

16

Country

USA

Material

Celluloid-covered mahogany

Dates / Serials

1938 (SN 686538), 1954 (SN 775526), 1959 (SN 350464)

Front

LC, A [B, T, ST, S] D, DI

Rear

L, DF [CF, CIF, CI, C] D

A 6.5-foot redwood classroom demonstrator modeling the full Deci-Lon 10 scale set, with a gravity-held plexiglass cursor rather than the real rule’s Ivorite construction.  I found this one on Craigslist in Austin — it still carries a Mineola ISD metal asset-inventory tag — and it hangs proudly in my own classroom today.

Made By

K&E

Scale Length

1.5 meters

Purpose

Demonstration/Training/Classroom

# of Scales

26

Country

USA

Material

Redwood

Date

1962 to 1967

Condition

C4

Front

Sq1, Sq2, DF [CF, CIF, L, CI, C] D, Ln0, Ln1, Ln2, Ln3

Rear

Ln-3, Ln-2, Ln-1, Ln-0, A [B, T, SRT, S, C] D, DI, K

A monumental cylindrical calculator — a 4” diameter, 18”-long rotating drum bearing the equivalent of an 80” logarithmic scale — and one of the most historically significant analog computers K&E ever sold.  My sample, serial number 2758 (c. 1910–1912), came through the F. Weber Co. of Philadelphia and is in unusually good condition, box-jointed mahogany case included.

Made By

K&E

Type

Cylindrical

Scale Length

30 feet

Purpose

High-resolution computation

# of Scales

3

Country

USA

Material

Brass frame on wood base; paper-covered scales

Date / Serial

1910 (SN 2758)

A cylindrical spiral slide rule with an effective 500-inch scale wound around a rotating papier-mâché sleeve — made entirely by Stanley Ltd. and only ever cataloged, not manufactured, by K&E. My sample, serial number 11376, dates to 1954.

The other Fuller variant in my collection, distinguished from Model 1 by an added sine scale on its fixed inner cylinder.  My sample, serial number 12165, dates to 1957, from very late in the device’s decades-long production run.

K&E’s only circular slide rule ever offered — a nickel-plated, pocket-watch-sized device with a full Mannheim-equivalent scale set.  My sample, acquired in July 2024, is smaller than you’d expect at just 6 cm across, and is missing the fob that would otherwise lock the slide in place, leaving it stiffer to operate than it should be.

An extraordinarily rare 10” German-silver rule from 1901–1903 — only about four samples are known to exist — with a solid triangular prism sliding inside a hollow outer shell and three distinct hand-etched scale sets across its faces.  Mine is the 4th known sample, found on eBay, missing its cursor; I’m weighing whether to hand-fabricate or 3D-print a replacement based on the original 1898 patent drawing.

A decimal-trig government version of the 4053 Polyphase Mannheim, never mentioned in any K&E catalog.  My sample carries the “U.S. LUTZ” stamp — LUTZ being a government resupply vendor, not to be confused with the unrelated Lutz Tool Company — placing it in the post-1962 production window.  See Chapter 6 for the full story of why K&E built a decimal-trig government rule instead of just supplying the cheaper 4161-3.

One of four WWII-era artillery rules of near-identical design from different makers.  My sample is the version badged for the American Blueprint Co. of New York rather than K&E directly, though it was manufactured by K&E on the same stock as the N4096 Merchant’s desk rule and Model 4110 Power Trig.  See Chapter 6 for the fuller story of this rule’s murky relationship between K&E, the U.S. military, and American Blueprint.

A custom rule commissioned by the Associated Spring Corporation in 1967 for designing spring washers, built on the same cheap vinyl-laminated, heat-pressed plastic construction as the K12-Prep.  My sample retains its black slip case and 13-page instruction booklet, and never appeared in any K&E product catalog.

A custom rule commissioned by the Mackensen C. Co. Inc. for quickly computing brick, tile, or gypsum board quantities against a job’s square footage, built on the same white-painted boxwood stock as the 4058W Beginner’s Rule.  No K&E model number, no serial number, no catalog appearance — just a rare and delightfully specific piece of trade history.

Made For

Mackensen C. Co. Inc., by K&E

Scale Length

10"

Purpose

Construction

# of Scales

4

Country

USA

Material

Unidentified, moderate hardwood

Date

1938–1942

Condition

C3

Front

Q-Quantity [M-Material, H-Height] L-Length