*"Dogs Playing with Slide
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David Crate's Quality Slide Rules

Last Updated: December 16, 2013

- David Crate's Quality Slide Rules - Current Feature: Eugene Dietzgen Co.
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*Slide Rule Basic Canon*(in development)- Classification of Slide Rules
*Canonical*Slide Rules- A Slide Rule Primer

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*"Slide Rule Express"*- The T-3-C Lamp by James Harvey Crate (my dad's website)
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*We
are currently featuring **the Eugene Dietzgen Co. **at
Crate's Quality Slide Rules: *

**A Tribute to the Eugene
Dietzgen Co**.

Dietzgen published numerous evocative
ads in popular magazines, celebrating the *Romance of New
Technologies* ...

The following ad ran in 1954. *Times have changed.*

I date this one from the mid-'50's:

A Dietzgen catalog from 1942:

The artwork was distinctive, even on the manuals:

We mustn't forget the slide rules!

Below: *Polymath Multiplex
Decimal Trig Type* Cat. No. 1744

(How did they thought up those names?)

And, one of the most lovely slide rules ever created ...

The Dietzgen-Tyler Multilog

Lousy indicator design, though.

- 1939 catalog -

An interesting process, obsolescence - but, what does it mean, really? These old things are no longer deemed useful. However, they still have value, perhaps of another kind. Really, they're just as useful as before, they haven't gotten "worse" at doing what they do - but if we know of something else that does the job "better", it seems we are compelled to abandon our old, faithful tools. Upgrade we must!

Click on the picture to visit Dietzgen's own history webpage. (No they won't sell you any slide rules, I've already tried!)

These instructions are for a Hemmi slide rule designed for problems in Electrical Communications. As most slide rules have a common set of scales, one can generally get by without a manual, or with a manual from another model rule. However, this approach is of no use in the case of the Hemmi 256. Thus, I am propagating the contents of a fairly ancient manual on the subject which was most graciously supplied by Mr. Cyril Catt of Lambton North, Australia.

Transcription of section: *Calculation
of Resonant Frequency*.

`Resonant frequency of electric
current with inductance L and capacitance C is expressed by: F =
1/(2*Pi*Sqrt(L*C)), where "Sqrt" denotes square root and "Pi" is the
famous ratio of a circle's diameter to its circumference. This kind of
calculation is done with the use of the L, C' and F scales. Symbolic
law of decimal point placement: F=L+C' (this determines the exponent or
power of 10 of the answer. The scales selected for L and C have
accompanying numbers, in red, to determine the exponent. These numbers
are summed and subsequently used to find exponent of frequency)`

`Example: find the resonant frequency for a circuit
if L = 7 microhenries, C = 50 picofarads.`

`Method: Set the red line F of the scale to 7
microhenries on the L scales. Set indicator to 50 pF on the C' scale,
under the hairline read 85 on the scale F. According to the symbolic
law of decimal point placement, from F=0+1=1, answer is found as 8.5
mc/s. `

I am now able to report encouraging news for sufferers of KERCS (K+E Rotting Cursor Syndrome). KERCS is a non-infectious but devastating malady endemic to 30's era K+E that were supplied with cursor guides composed of cellulose nitrate, a plastic with poor aging properties. After a few decades, the guides crumble and the cursor fall apart, leaving behind a beautiful but useless, slide rule. Now, working in collaboration with a California firm, we have developed prototypes of replacements for these pieces, made of modern, high-tech materials with better aging properties and close color and opacity matches. It is expected that these "K+E replacement cursor guides" will soon be available to the general public for a modest consideration. We will endeavor to keep you informed in the column. It would be appreciated if potentially interested parties would let us know of any interest at an early time.

KERCS Update (6-6-06)

They have finally arrived. Sets are available for $75. This includes both guides, eight tiny screws, and all shipping and related costs (they're small!). The material we selected is not as close a match as expected to the original color; it looked darker before it was cut into pieces! However, the parts are beautiful: one is etched with "KEUFFEL + ESSER CO. N.Y.", and the other with "PATENT 2,0862502". These parts are extremely faithful reproductions and will serve your slide rule well (even better than the originals). Please be aware that the supply is limited.

The plastic parts are milled on a numerically-controlled machine tool, drilled and tapped for the screws and then laser-etched with the lettering. The spring is then riveted on. Each piece is hand-finished.

Below is a photo of the prototypes:

And here is a photo of the production version:

A New KERCS Development: Reproduction K+E Indicator Frames (5-25-00)

We are being assisted in our effort to provide accurate reproductions of K+E indicator pieces by the former plant manager of the K+E plant in Connecticut. He presided over the shutting down of the K+E Slide Rule manufacturing operation there. He is redeeming himself now, however, by guiding us in the recreation of the indictor frames. We will be turning out a prototype in the next few months.

K+E Indicator Frames Update (9-2-02)

This project has undergone an indefinite delay as my partner's wife is ill and he has not been possessed of sufficient motivation to complete the prototypes.

Part one: a tally of "e"-sightings.
(Please feel compelled to make a contribution. I am particularly
interested in original ideas, so please send me an "e"-mail with your
"e"-notion and I will post it with an attribution.)

1. Euler's famous equation for sinusoidal functions

2. The kernel of Gaussian functions (which are, in turn, components of
all eigenfunctions of Fourier Transforms).

e. "e" raised to a power is an (the only) eigenfunction of the
derivative operator.

3. e is even implicated in the ratio of prime to non-prime numbers.
(Hadamard - the ratio of non-prime to prime numbers approaches a
finction of 'e', as the numbers involved go to infinitity.)

4. ... ?

- Editorial Section -

Slide Rule Babe says: *I cannot resist a man with a slide
rule, Grrrrr!*

So, Why Collect Slide Rules? (Other
than to attract brainy women)

A reasonable question! It seems that slide rules represent, for me, the optimal collector's item in that they are found at the intersection of three rather synergistic realms: 1. Aesthetics: many of them are works of technical art - wood, engraved and paint-filled celluloid, metal and glass - they possess the beauty of fine tools. 2. Mathematics - they teach a lot about math if one troubles to learn to use it - and on a wonderfully physical level. 3. Rarity - slide rules are at the wonderful time in their history when no one makes them (as far as I know) but there are still a fair number around and the people that remember using them are still around, too. It's fun! And I find that the people that appreciate them tend to be of a rather nice sort.

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Crate's Quality Slide Rules *is copyright © 1998-20014 by David Crate.