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. 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.
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.
The first
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.
The second
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.
The
column cursors
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
examples
to levels in the hundreds of dollars on what would otherwise be a $10.00 -
$20.00 rule.
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
I am
interested in any slide rule with one of these early cursors pictured, 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.
Slide
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
to.
Slide Rule Values
The first picture is of a relatively common but very collectable
slide rule
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 rather than anything resembling scarcity or the historical significance
associated with them.
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
interested in.
Please Contact
me with any early and
unusual slide rule that you have. I can help you with it.
have. On our sister site
www.Patented-Antiques.com
I have a good sampling of slide rules available for sale.
Please visit that site if you are looking to buy slide
rules.
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
www.Patented-Antiques.com and
visit the numerous sale pages you will find there.
Thank you!!
Larry & Carole
