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slide rule hoaxes

Slide rule jokes in the form of hoaxes and spoofs appeal to many collectors -- and not just on April Fool's Day. All of the following examples are from the International Slide Rule Group (ISRG) list, or predecessors, presented here in chronological order. See the Hoax Museum for much more on this form of humor.

Schmendrolog S153 Slide Rule Hoax.

Joe Levine (aka "JoeDentist"), now deceased, invented a rule called the Schmendrolog S153, complete with manual and box, and posted it as an eBay auction! For images see the Sphere Frankenrule site.

Message 986 on the ISRG List

Date: Fri Apr 2, 1999  5:23 am 
Subject: [sliderule] Schmendrolog a Hoax!  JoeDentist@... 
It has come to my attention that the slide rule I offered on EBAY was a
clever forgery. It seems that we have all been duped. The old Polish woman
that sold it to me must have been a clever mathematical device con woman. Now
even my six foot Bruning Demo Rule is in question,

It turns out that although the Schmendrolog sliderule does exist physically,
it was never produced in Poland, but is a modified Versalog, with red plastic
cursor ends, and new faces and edges. The evil person that perpetrated this
scandal will be sought out and punished severely. It turns out that the
Polska Firma Suwakow Logarithmiznch never existed, and the polish words on
the back translate to: "Write Calculations Here," and "Write Women's
Telephone Numbers Here."

I'm sorry if any bidders were attempting to actually buy the rule, but since
the reserve was not met, there should be no dissappointment. After all, I was
fooled, and I've been collectiing for almost three months now.

What a dissappointing world we live in when even slide rule descriptions on
EBAY can not be trusted to be completely accurate. I mourn my innocence.

Joe Levine

[Here is the descriptive text for the eBay auction:]
This item has just recently come into my possession from an estate sale.
The story given me is that in the late sixties, the Polish government
wanted to establish a machine tools industry comparable to the Germans. In
order to seal the quality image, they decided that they needed to produce
their own slide rules. They chose to produce a bamboo/celluloid duplex rule
similar in quality and design to the German Dietzgen 1738's or Post
Versalogs. The Poles made two big miscalculations however - 1. The advent
of the electronic calculator was just about to render slide rules obsolete.
and 2. Is was extemely difficult to grow bamboo in Poland. A company called
PFSL was formed to produce the rules, which were branded Polski. Anyway, a
few prototypes and early production rules survived. This is one of the
early Schmendrolog production models -the top of the line model - and it
has some unique features. The front of the rule is pretty standard, but the
back side has only half length scales - the rest is mostly blank except for
the cryptic polish words "WPISZ OBLICZENIA TUTAJ," and "ZANOTUJ NUMERY
TELEFONICZNE KOBIET TUTAJ." It seems that here was a big shortage of scrap
paper in the Communist world, and the back of the rule was a sort of
erasable blackboard, where the Polish scientist or engineer could record
notes about the calculations in pencil. An eraser attached to the cursor
would erase the notation area, sort of like an Etch-A-Sketch. The eraser is
missing. Although this feature was never fully implemented, it is
interesting to note that scientists were so enamored of this feature that
they used the concept of "Reverse Polish Notation" in the earliest
calculators and computers. This was also the first known appearance of the
RND scale, an abortive atempt at slide rule random number generation. The
rule itself is in pretty good condition considering its age, with some
corrosion on the cursor frame and end pieces, and the box is a little
crushed and spotted. The sheath is some sort of nylon and has the classic
Polski "mummy" shape. The cursor ends are the easily identified Polski red
plastic ( A bow to the Soviets perhaps?). This would make a fine addition
to any collection. Polski rules are hardly ever seen in this country and
rarely in this good shape. Note that the box and manual (in Polish) use the
Pre-1970 Polski logo, and the rule has the post-1970 logo, so this is a
true transitional model. Polski quit production in 1971, and I take this to
be an early '71 model. Buyer pays postage of $3.20 to any US location. (If
you have any questions, E-mail me and refer to item AFD-153.) Big composite
picture takes a while to load, but its worth it!

Left Handed Slide Rule Hoax.

Ron Manley posted an example of what he claimed was a Blundell model 401, designed for use by left handers, with all the scales reversed. The tip-off was the model number, April 1st!

Message 7786 in the ISRG List
Date: Tue Apr 3, 2001  1:32 pm 
Subject: Re: SV: [sliderule] Left handed rule - hoax  sliderules@... 


The first part was easy - reversing the image. The next part was
tedious - reversing the individual numbers. Though what I did was to
have two images, one normal and one reversed, open at the same time
and cut and paste from one to the other. Fortunately the software I
use, Micrografx, makes it fairly easy to have irregular shapes for
cutting and pasting.

I'll email Walter a copy.


Ron [Manley]

Slide Rule for Dummies, Book Hoax.

Chris Redding made an imaginary addition to the "For Dummies" allegedly authored by Paul Reubens (of PeeWee Herman fame) and titled Slide Rules for Dummies. This prompted Jim Cerny to draft a page for an imaged Slide Rules for the Innumerate (PDF).

Message 8477 on the Yahoo ISRG list.

From: Chris Redding  
Date: Thu May 10, 2001  6:02 am 
Subject: New book on the slide rule scene  credding@... 


Searching for books on eBay, I found a new book "Slide Rule for
Dummies" by Paul Reubens. The URL to the Dutch auction is:


Check it out gentlemen.

Take care,


Yuri Gagarin Slide Rule Hoax.

Jim Cerny commented on an auction house that was selling a slide rule signed by the Soviet Cosmonaut, Yuri Gagarin. Jim's posting was followed by Ed Chamberlain's impressive description of an encounter with Yuri Gagarin. The tip-off was the date, since Gagarin died before 1973. As far as we know, everyone was taken in!

Message 19145 on the ISRG List.

From: Ed Chamberlain  
Date: Sat May 24, 2003  11:18 am 
Subject: Re: SR a Yuri Gagarin flight slide rule on eBay???? 
TO: Jim Cerny and those interested in Gagarin's slide rule:

In 1973 I spent a bit of time in the Soviet Union including visits to
eastern Siberia and the Baikonur Launch Site. During that visit I met and
had dinner with Yuri Gagarin. We talked about various items of common
interest including flying and engineering. When the subject turned to slide
rules, I was amazed to find out that Yuri was also a slide rule collector.
He had an example of every slide rule made in Russia - including one of the
big "Manhole Cover" circular artillery slide rules that the Soviets made
for the East Germans. As a favor for me, Yuri autographed several flight
computer slide rules for me with his name "Gagarin, Yu." on the side of the
slide rule in violet ink. I still have one of these left and would be
willing to sell it to the underbidder on this auction for a fair price.

Do svidaniya & Schastlivo ostavatsya !!

Ed Chamberlain

At 03:23 AM 5/24/2003 +0000, Jim Cerny wrote:
>I usually resist the temptation to comment on strange eBay slide rule
>auctions, but can't resist this one.
>Someone (a gallery, not just a stray individual) has listed what they
>claim is the slide rule (flight computer) owned by Yuri Gagarin,
>allegedly inscribed by Yuri. See auction item 2176168261. Best of
>all, they have a price estimate of $5K-$7.5K on this, with starting
>bid of $2.5K. Oh yes, and they want to charge a 20% buyer's premium!
>The rule appears to be the quite common Russian flight computer that
>shows up on eBay and other places. The auction is poorly illustrated
>and except for providing a story about the rule, provides no
>provenance. As proof that I have too much time on my hands this
>evening, I just wrote to the seller to ask how they know it really
>was Yuri's. If I get a particularly interesting answer I will share
>it with the list.
>If you bid on this, please let me know, because I have an Albert
>Einstein Nestler slide rule you might be interested in as well!!
> - Jim Cerny

Images were saved by Jim Cerny at the time the hoaxes occurred. Text for the original postings was obtained from Rod Lovett's ISRG archive.

Thacher for Children Slide Rule Hoax.

This hoax, written by Rod Lovett, was pulled on April 1st 2011 on the ISRG,
Message Number 40691, "A miniature Thacher for Children". Rod writes that he was
quite pleased with it since it claimed some notable scalps, including Ed Chamberlain!

ISRG Number 40691. A miniature Thacher for Children Posted April 1st 2011

There is no doubt that serendipity can play an important part in the life of a slide rule collector. It started when an international flight to Osaka in Japan was diverted for reasons about which the pilot was quite vague. After circling for what seemed like for ever but probably was only a couple of hours and running low on fuel we were diverted to the nearby Kobe airport across Osaka Bay.

Our group, attending a conference on 6th generation programming languages, decided to stay in Kobe for the night and move on to Osaka the following afternoon. In the morning we decided to explore the Kobe Port Tower and it was there I met an old (by definition anyone at any time who is fifteen years older than me is old) chap who immediately recognized the Aristo 868 I carried in my top pocket and became extremely animated. He had no English and I have no Japanese but in our group were two proficient Japanese speakers (sadly not interested in slide rules) who said that the Japanese chap (whose name as I later found was, or as close as I can make it, Sato Hiroshi) was claiming that he collected "keisanjaku" and had a "very small, very rare cylindrical keisanjaku" which he called a "thecha". The Japanese translators being quite young (fifteen years younger than me is quite young) didn't understand the word "keisanjaku" but got the impression it was some sort of calculator - in this they were correct. The word "thecha" struck a chord and I asked him how small? He held his hands about 12" apart. I asked him whether perhaps it was really about 2 feet long, holding my hands out by that amount and he said , "No!, no! no!" and held his hands out again at about 12" apart.

Would I be interested in seeing his collection? Since he lived not far away and since one of the Japanese speakers was prepared to come with me off we went. Most of his slide rule collection was fairly disappointing - consisting mainly of modern Hemmi's and Shanghai Flying Fishes although there were a considerable number of pocket rules of Japanese origin that I did not recognise. However he had two absolutely amazing small Thachers. Roughly half the size of a conventional Thacher they were beautifully made - in fact works of art. (A picture of what was to become mine can be seen here:)


Over a period of two hours, writing copious notes and with much repetition from the interpreter this is the bare bones of his story fleshed out later with details of the larger picture.

Shortly after WW2 an American, Dr. W Edwards Deming, who was part of General Douglas MacArthur's administration during the occupation used his ideas on Statistical Quality Control to help Japan rebuild its manufacturing infrastructure. (This methodology, in which quality control was central, was to enable Japan in less than twenty years to out-manufacture in terms of quality the combined might of the United States and Europe. A fascinating account can be read by Bruce Craven, "Thoughts on Japan, Deming, Quality and the Statistical Quality Control Slide Rule", in the Journal of the Oughtred Society Vol. 9, No 2, Fall 2000 Pg 59.). The mathematics involved was not straightforward and it was long before statistical rules such as the Pickett Model 6 had been developed. The Japanese were determined to use these statistical techniques (long before the Americans and Europeans) across the whole range of their manufacturing industries but quickly came across a problem. They had a completely inadequate number of mathematicians for their requirements. Then someone had a brainwave, The calculations, although complex, could be broken down into a long sequence of much simpler calculations involving only multiplication and division. A production line of human calculators (called computers in those days!) would be used in which successive result were passed down the line and once the line (of fifteen) had been filled - effectively priming the pump - a high level of parallelism and hence speed could be achieved. A squad consisting of two teams of fifteen calculators each was used and a result was accepted if the two teams had agreement within 1% of each other. It was quickly realized that conventional slide rules, even 20" ones, created rounding errors which quickly built up and made the results meaningless. However, Thachers and Fullers were more than accurate enough. The problem of manpower remained. It was decided at a very high level, but by whom remains a mystery, that since the need was so urgent and there was a dearth of manpower then, in the short term, teen-age children could be used for this purpose. In a trial of a Fuller it soon became apparent that, although accurate enough, it was just too awkward for the children to use and hence too slow; even by reasonably adept children in their mid-teens. At this point they moved their trial to a Thacher which again proved accurate enough but again was awkward to use because of its size and the comparatively small physiques of, in the early days, the somewhat malnourished children. However it was considered to be capable of greater speed than the Fuller and a remarkable decision was made, ignoring all patents, to create a batch of reduced size Thachers suitable for children. After brief analysis of a typical child's range of movements, it was decided to reduce the size of a Thacher from approximately 22.5 inches to approximately 12.5 inches. Somewhat surprisingly this had very little impact on the accuracy (or do I mean precision?) of the device. In the amazing short time of three months, a prototype had been created which proved eminently satisfactory and over the next two years a small factory in Kobe built, it is believed, approximately 3000 of these devices to be circulated to 100 squads scattered throughout Japan. Was this the start of what was to become the Japanese talent for miniaturization?

Sato Hiroshi was a calculator in the only squad based in Kobe. The operational life of a squad was approximately 3 months after which burn-out set in rapidly and accuracy dropped off. Rather than replace complete squads at the same time, a program was introduced to replace members in the squad at set intervals to minimize the disruption. (It was very quickly noticed that whilst boys were significantly faster than girls they lacked the staying power and needed more breaks than the girls. The organization of such teams therefore was quite difficult.) The whole program was eventually wound down after approximately five years - why, Sato did not know but felt that it might have been due to government pressure concerned about the "inappropriate" use of the children. Sato, though, had nothing but praise for the program which he said gave him, and others, a life long interest in statistics and led him to become a teacher of the subject.

Sato Hiroshi was in the last operational squad in Kobe at which time the rules became surplus to requirements. How he acquired the two mini Thachers I do not know and did not ask! I made it quite clear that I would love to buy one of the mini Thachers and he made it quite clear that he really wasn't interested in selling. At some point a mismatch of cultures developed. Apparently I should not have made my disappointment so obvious. On seeing my manifest sadness he gave it to me for nothing! I couldn't possibly accept such an offer and made this quite clear at which point he gave all the indications of being somewhat insulted. The interpreter who was in the middle of this mismatch eventually solved the problem by suggesting that I accept the offer but then pay a significant amount for the wooden box in which it came (itself a minor work of art)! Honor was thus satisfied and we departed on very good terms.

The conference on 6th Generation Programming Languages was an absolute waste of time; it does seem as if Java, Ruby, Python,C++ etc., etc and of course Fortran are going to be around for many years to come. And I never found out the reason for the diversion of our aircraft from Osaka to Kobe but I'm grateful as it led to the most memorable event of my slide rule collecting career! Rod


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last modified March 04, 2017