We deal in, buy, and sell early and unusual slide rules and early patented calculation
devices. We also deal in many other
related antiques and collectibles. We specialize in
tools and technology related antiques from the home, shop, farm, or office.
We are full time antique dealers of early
scientific and technology related antiques and actively
deal in a broad range of related antiques and related advertising.
www.Antiqbuyer.com is our informational and past sales results website.
There are links on the left to informational pages, and on the right are
links to past sales results for many scientific related antiques we have sold.
Our antique sales site for these
and other types of antiques and collectibles is
Please visit it that site if you are looking to buy these types of
antiques and collectibles.
contact us by email at LCM@AntiqBuyer.com
if you have any interesting technological or scientific related antiques
you want to sell, or want to cosign to us to sell for you.
Below are some pictures of the
types of scientific antiques and vintage calculation devices and slide
rules that we deal in and are seeking, along with some basic information
to help you determine what you have.
picture below is of the ever-popular Curta calculator. The example
pictured is known as a Type 1. This step drum
calculator that was also produced as a
during the same time frame. The
main differences in the two calculators are that the type 2 Curta
calculator has a larger capacity. These calculating devices were first designed
during WWII and were introduced shortly after the Second World War to
the commercial market. They were still being made right
up to the time the hand-held electronic calculator caused their popularity to wane
and production to end in the 70's They originally retailed for about
$150.00. For most of the 70's and into the 80's examples sat on
shelves and in back storerooms of drafting supply shops as dead stock for
years. Before the internet it was
oftentimes hard to even get original retail for them. Prices
climbed and held steady for a number of years at around 200. After word got out that they were being
collected and a constant supply and demand became available on the internet, prices skyrocketed.
Not too many years ago these devices could be had for a couple hundred dollars and there were
more than enough to go around. The supply seemed
endless, and the demand scant. The Internet auctions came and the
market changed with a new group of collectors entering the market.
Prices initially went up to new unheard of levels and then back down after that initial demand was
fulfilled and the tech bubble blew up. They are still a popular collectible and demand is pretty
constant with prices for them ranging anywhere from $500-1500.00 or so
depending on a few variables including the serial # and condition.
Antique Calculator Values
The prices of most later or more modern
electronic calculators also took off for a while and reached new and unheard
values when demand rose right after the internet came into vogue.
Many of those values dropped considerably after the tech bubble burst. The
value of these calculators seems to be tied to the amount of money folks
of the proper age group have to spend as disposable income at any given
time. High when the stock market was doing well, and not so well
after the bubble burst. That scenario has repeated itself during
this latest recession as well and I am willing to bet the same is true
in relation to what happens in the Real Estate market. Prices and
interest rise in good markets and fall in bad. I expect that
things are going to be soft for a while. It seems the only modern
calculator to buck this trend are the examples of early Apple computers
bringing 6 figures at auction.
A market was also created
by the internet for electronic hand-held calculators from
days and evolved during this period also. Another new collectible was born. It seems that this category bubble went the same way as the
last NASDAQ bubble as well. I would bet a chart comparing the two price levels would look
very swimilar. The difference being that this may have been more fad than
real. Think Beannie Babies here. I think it
will be years, if ever, before some of the lofty
heights that some of these later electronic calculation devices and other collectibles
once brought is met again. The one caveat being the rare of
the rare still do well with the prime example being the Apple 1 computers selling
for half a million
or so. Results like that are explained by some folks
simply having too much money.
like, and still look for these handheld electronic calculators, but rarely do I want the
larger later and more typically seen modern 10-key model
calculators or adders, like those from the 30's or 40's or later.
large Victors, Burroughs,
and a host of the other later 10-key heavyweight adding machines that seem to be in every garage and in
every antique booth and even at the end of some ropes in the bottom of
people's boats acting as ballast or anchors. There are people who do collect and are looking for
these later machines, but I do not know them and have no market to sell
Check eBay to see what most of these later 20's - 60's era calculators / adders actually sell
for and you will see what I mean.
Early Calculation Devices
Antique and vintage calculating devices have had an interesting and varied period of
development through the years.
one is familiar with the abacus,
one of the earliest of all calculating devices.
Another early form of a
calculator first developed
for Western civilizations was known as Napier's Bones. These were cubes
or dice-like in shape, and were made from bones or ivory
and real examples are extremely rare and collectible. They are being
reproduced today and sold at various internet sites and auctions, at times with no
indication of their true vintage. Be aware.
Logarithmic scales found on slide rules were first introduced by Routledge in the early 1800's and were incorporated into
the various forms of rules
and other devices that were the forerunner to the slide rule as we know
it today. These scales were typically found on rules during
the early to mid 1800's primarily for use by merchants and trades people
who needed a viable way to run larger calculations for their lines of work
One of the
first types of mass produced calculating devices that still survive in numbers today
tables with wheels and dials similar to the adder that is pictured
above on the right. The Palmer's Computing Scale
(not shown) is the
best known and most commonly seen of these types of early paper calculators.
Other variations do exist and are good pieces.
Early Dial type calculators / adders were around pretty
much during the same period. The best known of this style machine
the well known Webb Adder which was patented in the
late 1800's.. These
were produced in a few different configurations
throughout the years, with the earliest versions having a wooden back On the right is the later version, this one being marked with the
maker's name and patent date. There
are early knockoffs of this calculator / adder that are not marked that
can found as well. They were produced to
compete with the real things, much as the pirated tapes and CDs that abound in today's
the left is a pretty rare and earlier model
adder / calculator with this same basic
configuration as those above. It is known
as the Hart
I am interested in any of these kinds of
early dial calculators, sliding style calculators, or circular calculators like the one in the
top left corner.
Please note that there is little market for newer sliding adders
like those by the German firm Castell and the Japanese ones from the
1950's that were marketed after World War II and sold from novelty
catalogs and the back of magazines for a $1.00 or so.
I am an active antique
dealer in early or antique calculation devices and looking to add nice
the sale pages on our sales website located at
www.Patented-Antiques.com I have a good selection of slide rules, calculators, adders and other early
office and scientific antiques listed for sale there. Please take a look if interested
in buying or selling.
Key Type Calculation Devices
Near the turn of the century dials began to give way to
key type adders and calculators, or those with stepped drum and
mechanisms, and when these stepped
drum and pin-wheel models became more economically feasible to manufacture, even though they
were invented years earlier they soon dominated the market.
style calculating machine, which quickly and easily performed four functions,
standard. Shortly thereafter calculators became electrified and all of these old style calculators
were pretty much relegated to the status of
obsolete but not necessarily collectible. Millions had been produced
and they are still readily available.
The story of the electronic calculator, and the design changes that they
went through in a very short period of time until arriving at today's
wonders of technological advances is a dramatic and interesting story.
There is a very informative and well done site that is primarily focused
on the history of the Hewlett Packard line of calculators, but they also
have a very nice and well done history of earlier calculation devices
leading up to the HP line.
A more detailed history of this period can be
found at The Museum of HP Calculators.
It is interesting reading and should be looked into if
you are trying to identify your calculator, or if this is the sort of
thing that interests you.
The most famous, and most
commonly found early key style calculating machines is the
Comptometer. It was a very popular machine in its day, as attested to by the
sheer number that have survived and are still available. The most
common versions are found in a tan metal case and sell for under 100 in most cases, but the earliest version came housed in a wooden
case like the one pictured on the right and is much harder to find. These have been known to sell for several
thousand depending on condition, serial number, and other factors.
10 key machines by other
makers that look similar to this with metal cases
(like the Burroughs) are considered very
common and of little
interest to me or to most other collectors of early
calculating technology with limited storage space.
Other non electric calculators considered collectible operated with the
stepped drum or
pin-wheel mechanism. Some of the names of these style machines
the Marchant, Odhner, Time is Money (TIM), The Millionaire Calculator, The
Peerless Reckoning Machine which was sold by K & E, as well as a host
of others that were being produced early on. In general the earlier
the better, with some selling for 1000.00 or more and others 100 or
& Other Scientific
Below are some pictures of the
types of scientific antiques and vintage calculation devices and slide
rules that we deal in and are seeking to
buy or help you sell. I
will provide some basic information
to help you determine what you have and hopefully help you recognize
some better and more desirable slide rules and calculators.
I am an
active antique dealer interested in antique and
collectible slide rules and other calculation devices that date from the
early 20th century and before. This page is a basic
primer describing the different and various types of scientific and
calculation devices we buy, sell, deal in, and can help you sell.
Keuffel & Esser Slide Rules
A Basic K & E Slide Rule
Cursor Lesson or
Beginning Primer for the Curious
The next three pictures give views of different early cursors (the sliding window portion)
employed by Keuffel & Esser or K & E and represent the transition
or changes that slide rule cursors have gone through. This is by no means
the full story, and there are variations and other designs by other
companies that are not covered here.
picture of the all brass cursor on the right is referred to
as the Christmas tree
or chisel point cursor. This style cursor is considered the first model K
& E used and dates from a bit before to near the turn of the 20th century.
It is rare and desirable. It can cause what is otherwise a $10.00
sliderule to sell for several hundred to $1000.00 or more.
It has no glass window like later model slide rule cursors do. You
would work off of one of the tips to do your calculations. Some are
like this one with the points going out to just one side and other K & E
cursors have points on both sides of the center post or upright.
picture shows what is known as a clamshell cursor. This was the
second cursor employed by K & E. Some examples are pretty rare, others on
common rules, are not.
The clamshell design was replaced by the interesting looking and difficult
to find column column cursor which is pictured below on the right.
still show in the 1913 catalogs, but were phased out shortly after that. This cursor style was only used for a few short years and affects the value upward for most
to levels in the hundreds of dollars on what would otherwise be a $10.00 -
K & E kept extensive records of
their production and through research it is pretty well known how many of
each type of cursor was offered and by scanning through the early catalogs
when the cursor style changed and what models were offered when.
The next cursor to be
used after the column cursor was the short lived frameless cursor.
(not pictured here) This design was an attempt to save money and material
and give the slide rule cursor a sleeker look over the earlier
designs. It was a disaster as they were very fragile and
prone to break at the connection points in the corners that had holes
drilled through the glass. This style cursor does not add much of premium even though it is hard to find them not broken or damaged.
K & E
shortly thereafter introduced the standard framed cursor that most slide rules found today have.
After K & E introduced
their standard framed cursor, that basic design was used until production of slide rules ended in the
late 60's or early 70's.
Slide Rules Wanted
interested in any slide rule with one of these early cursors pictured
above, or slide rules with any other
unusual cursors that some other companies used. Some of these had small decimal keepers
or counters on
them, or moveable arrows, or in one case a small
abacus to help you along with your calculations and in keeping track of where the
decimal point belonged. Some also had magnifiers built into the cursor.
K & E offered clip on magnifiers.
I am also
interested in any special use slide rules. Slides Rules with scales
especially designed for surveying,
chemicals, electrical calculations, aviation, and others are sought. There were many slide rules produced
to help the scientist,
machinist, shopkeeper, workers and others with the daily computations that they were faced with
in performing their jobs.
rules are an emerging collector category, and different folks collect them for different reasons.
Each of these groups feels that different
ones are worth different amounts for different reasons. If that
seems confusing, it is, and prices and supposed values of these interesting
collectables fluctuate wildly depending on which group you are listening
Slide Rule Values
The first picture is of a relatively common but very collectable
put out by K & E or Keuffel & Esser. It
is known as
the Deci-Lon and was one of the last sliderules K & E
made or offered.
It is all plastic and was produced for a number of years, with
the last models being designated by the model number 68-1100.
Before the Internet and the beginning of their "known" or
documented popularity this rule could be had routinely for $20 or less and
was routinely passed over by collectors and those in the
"know" who were looking for earlier and rarer examples of slide rules.
Today this rule routinely brings $100 or so, not because they
are scarce, but rather because they are popular. The 5" version sells for
even more for the same reasons. The collecting frenzy over them and
the resulting prices they bring is largely driven by
the same impulse that has created a desire for collectibles like GI Joes
and Barbie dolls, that being the current generation buying back their
childhood, rather than anything resembling scarcity or the historical significance
associated with them. In this case nerds as opposed to cheerleaders
The point is that there are many earlier and somewhat rarer slide rules
that are not having a lot of attention paid to them these days
that have potential
to be worth more in the long run, and these are the rules that I am
me with any early and
unusual slide rule that you have and want to sell. I can help you with it.
I am also interested
in other scientific or technology related antiques, including surveying
instruments, other early calculation devices and early patented adders that
date from the 19th century and into the early 20th century as well as a
host of other related antiques. Please see those other pages in the left column to see or read more. I have many past sales
results in the past sales archives that can be accessed through the link in the right column.
To see examples of many slide rules and
calculators I have sold
in the past please go to the Past Sales Results Archive.
To see examples of similar antiques that
we currently have for sale please go to our sister site at
visit the numerous sale pages you will find there.
The above adders / calculators are an example of
the caliber, condition and quality of these types of devices that we are
primarily interested in. To see examples of calculation devices we
have sold in the past please look at the sales archive pages listed on the
If you have or know of one of these
earlier and interesting adders / calculators that you want to sell please
contact me at LCM@AntiqBuyer.com