Aristo Darmstadt Nr. 867U

October 14, 2007

This was my first slide rule. It was my father’s, and he gave it to me when I was old enough to learn how to use it, but sadly not old enough to look after it well. As a result, the one I have is somewhat marked up, chipped, and missing its cursor. I’ve been on the lookout for a replacement, but in the mean time, I’ve been using this one in my workshop (using a small engineer’s square when I need a cursor). Here’s a scan of the front of the rule:

The Darmstadt style rules have single sided stators, with a reversible slide. The back of the slide contains the log-log scales. Here’s the whole rule again, with the slide reversed:

A feature of this rule that I really like is the Pythagorean (P) scale, which computes √(1-x2). This scale is especially useful in conjunction with the Sine (S) scale. When an angle is selected on S, the D scale gives its sine as expected. At the same time, the P scale gives the cosine of the same angle. None of my other rules except the Hughes-Owens 1777 have this useful scale.

Another unusual feature of this rule is the centimetre and inch scales along the rule’s edge. Although not intended as a drawing or measurement instrument, these scales can come in handy at times in the workshop.

An interesting aspect of this rule (and other Darmstadt-style rules) is the location of the trig and log-log scales. Most of the rules in my collection have the trig scales (S and T) on the slider, and the log-log scales on the stators. The Darmstadt is opposite.

The following is the description of the 867U (and its 25cm/10in and 50cm/20in siblings, the 967U and 1067U) from Aristo’s catalog:

ARISTO Darmstadt

The original scale pattern of the Darmstadt system is in the ARISTO Darmstadt rule extended by the addition of a scale of reciprocals, BI. The Log-log scales, placed with a mantissa scale on the reverse of the slide, are visible over the whole length of the slide, through the transparent rule body, making possible the use of the rule with the slide in its normal position. Non-slip rubber inserts (model 967U) facilitate single handed working, with the rule on the desk top. Pocket model ARISTO Darmstadt 867U/400g is also available, graduated in the new 400g system.

If I’m unable to find a replacement 867U, I may attempt to make a new cursor for the one I’ve got, although I’m not yet sure exactly how I’ll go about it.

Make and Model: Aristo 867U
Manufactured: Germany, Year Unknown
Overall Dimensions:   15.9cm × 4.6cm × 0.5cm (6.3″ × 1.8″ × 0.2″)
Scale Length: 12.5cm (4.9″)
Construction: All Plastic
Scales: cm | K A | B BI CI C | D P S T | inch
Cursor: Plastic with Single Hairline (missing)
Date Acquired: 1974 (approximately)

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  1. John Mosand
    February 28, 2008


    When I saw that your Darmstadt is missing its cursor, I searched my drawer with dozens of spare Aristo cursors, springs and screws. Surprisingly, I didn’t find any for your SR 🙁 If I come across one, I’ll let you know. A couple of comments: You state that its missing cursor has one hairline. It should say three hairlines. 400g? They are commonly called "new degrees" but, there isn’t much "new" regarding those! They were introduced during the French revolution in the late 1700’s as part of the ‘metric redefinitions’. They have been standard for surveying in many European countries for more than 100 years!

    Best wishes! John

  2. Jarno Mäkinen
    October 27, 2010

    LOL Nice! Hawt calculator!!1

  3. Jos Aarts
    December 21, 2010

    I have an extra cursor for the 867u.

  4. Donald B Terrana
    October 20, 2012

    Dear Stefan,
    First, I own a like new (can’t tell it from brand new) Aristo 867u slide rule that I purchased in Santiago Chile in 1970! I would be happy to sell it to you at the market price, whatever that is.

    Second, you an I have alot of things in common. I’m a retired Aeronautical Engineer and all my life I have designed and built electronic devices for my airplane and photographic projects. Probably the most complex was a densitometer using a photo multiplier tube.
    I have just under 2000 flying hours having flown all over the united states including alaska.

    And, lastly I used to love Lamy pens! In fact I got into trouble while departing from Mexico City airport when the Mexican customs agent wanted my pen as I was signing out. I gladly gave him a generous tip as long as he let me keep my lamy pen!
    We live in Venice Florida, I am retired from both Boeing and Grumman aerospace.
    AS for my European experience I spent two years (1967-1968) in Lausanne working on the Ben franklin submarine program.
    I could not see where you are located now, but I assume it is somewhere in Germany

    Please send me reply quickly as I would love to “talk” aviation and many other topics with you.

    Yours truly.
    Donald B Terrana

  5. Paul Jaramillo
    April 25, 2013

    YO tengo a mi dispocision un Aristo Darmstadt Nr. 867U si aun etsas interesado en adquirirlo ponme al tanto

  6. paul
    January 30, 2014

    i have what your looking for i think

  7. giacomo
    February 21, 2016

    Ho un Aristo 867u perfettamente integro vorrei sapere come funziona.
    [I have a perfectly intact Aristo 867u would like to know how it works.]

  8. Alan Barbour
    February 06, 2019

    I have an Aristo 867U with the cursor. I also have a 967U. They both have four cursor lines, but the larger rule has them partially numbered. There are two “extra” marks for the C and D scales, to the left and right of the main cursor. Place the left mark on the number of kilowatts and the right will give horsepower [PS–not quite the same as English/American horse power, I think but am too lazy to check right now]. There is a single extra cursor mark to the left of the main cursor line for the A and B scales; place the cursor on the diameter of a circle on the C or D scale, and you can read the area of the circle on the A or B scale.

  9. Stefan Vorkoetter
    February 06, 2019

    Thanks for those details Alan. I have recently purchased a 967U, and it has the marks you describe. Is your 967U the one with the clear rulers on the edges, or the white ones?

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