# Identify this device, please **URL:** \ **Category:** Factual Questions\ **Created:** [November 6, 2021, 4:09am UTC](https://boards.straightdope.com/t/identify-this-device-please/953876 "2021-11-06T04:09:49Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Hatchie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hatchie/32/3983_2.png) [@Hatchie](https://boards.straightdope.com/u/Hatchie)\ **Post date:** [November 6, 2021, 4:09am UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/1 "2021-11-06T04:09:49Z")
Photo I found in the pages of a book I snagged from a Little Free Library. It was a cookbook, but I don’t think this has anything to do with food. I thought it might be an old telegraph key, but now I’m not sure. Google Images says it’s a cylinder. Thanks a lot, Google Images. TinEye didn’t even try to name it. Maybe you can. [![Imgur](https://i.imgur.com/HHW9fN9.jpeg "imgur.com") ](https://imgur.com/HHW9fN9) ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [November 6, 2021, 8:14am UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/2 "2021-11-06T08:14:56Z")
It looks like a highly accurate electromotive experimental device. Basically either/or a motor of generator. The entire thing is on a three point adjustable stand, clearly to enable precise levelling. There are a pair of field magnets with pole pieces that wrap part way around the armature. In the middle is the armature which is coupled to a pulley on the right side of the frame. The armature has some form of commutator at the bottom, and what appears to be a balance adjustment above that. I would guess it might have been used in a university level electrical labs teaching electrical machine theory. Similar devices are still in use. Just a little less pretty. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [November 6, 2021, 9:58am UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/3 "2021-11-06T09:58:02Z")
To add to the above. The commutator appears to be a pair of rings, which suggests an AC motor. If used as a generator it would need external excitation current for the field windings. It may be that the intent is that it can be wired in different configurations for different experiments/demonstrations. ---
**Author:** ![Bonum\_Legatum](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bonum_legatum/32/6183_2.png) [@Bonum\_Legatum](https://boards.straightdope.com/u/Bonum_Legatum)\ **Post date:** [November 6, 2021, 11:10am UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/4 "2021-11-06T11:10:56Z")
Nice pillars at the right and left. Someone went through a lot of trouble to machine the pediments and taper the tops. I’m surprised that they didn’t flute them while they were at it. Notice the large pulley at the right side, leading to cables and pulleys, which suggests that the bit in the center is spun around while being tested. This reminds me of a machine that geologists use to check residual magnetism in rock specimens. The only thing is - their machines have wires wrapped around the outside to counteract the effects of the earth’s magnetism. ---
**Author:** ![Bonum\_Legatum](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bonum_legatum/32/6183_2.png) [@Bonum\_Legatum](https://boards.straightdope.com/u/Bonum_Legatum)\ **Post date:** [November 7, 2021, 7:54pm UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/5 "2021-11-07T19:54:42Z")
Could you try to read the writing on the black rectangle in the center? I can barely make out the letters “Dix”, on the first line and a (maybe) a capital “J” on the second line. Upon further thought, I agree with Francis\_Vaughan. This is an early form of demonstration electric motor. There are two u-shaped springs at the bottom of the rotor that make contact with the poles at the left and right as they pass by. A primitive form of commutator. Then there is the rotating electromagnet just below the stepped pulley. It would be a cylinder like the two stationary coils at the right and left. But this is shown rotated about 90 degrees so we can only really see the one endcap. I can’t explain what the mechanism is between the commutator and the electromagnet. Here’s a link that shows a two-pole motor made with a commutator and magnets in place of the two stationary electromagnets. > **[2 Pole DC Motor Kit](https://www.instructables.com/2-Pole-DC-Motor-Kit/)** > > 2 Pole DC Motor Kit: In this Instructable, you will be making a 2 pole electric motor. The way this works is the armature is turned into an electro magnet and it is attracted to 2 permanent magnets. When it reaches the magnets though, the polarity... ---
**Author:** ![Marvin\_the\_Martian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/marvin_the_martian/32/2898_2.png) [@Marvin\_the\_Martian](https://boards.straightdope.com/u/Marvin_the_Martian)\ **Post date:** [November 7, 2021, 8:09pm UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/6 "2021-11-07T20:09:36Z")
Maybe a patent model? Until 1880 inventors were required to submit miniature working models of their invention when applying for a US patent. The practice continued for a while after the requirement was dropped. ---
**Author:** ![Hatchie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hatchie/32/3983_2.png) [@Hatchie](https://boards.straightdope.com/u/Hatchie)\ **Post date:** [November 8, 2021, 7:55am UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/7 "2021-11-08T07:55:38Z")
Here is a blowup of the plate. Still hard to read. The original is a Xerox of someting printed in a book or magazine. [![Imgur](https://i.imgur.com/UrcSYY6.jpeg "imgur.com") ](https://imgur.com/UrcSYY6) ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [November 8, 2021, 9:23am UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/8 "2021-11-08T09:23:14Z")
The more I look at the component in the middle of the vertical axle, the more it looks like an adjustable centrifugal governor. Pretty agricultural, but it would probably work. Still not a complete story however. The dual rings at the bottom mean there is no polarity reversal as the armature rotates, which restricts the possible operation modes. ---
**Author:** ![Bonum\_Legatum](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bonum_legatum/32/6183_2.png) [@Bonum\_Legatum](https://boards.straightdope.com/u/Bonum_Legatum)\ **Post date:** [November 8, 2021, 11:19am UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/9 "2021-11-08T11:19:33Z")
Thank you. The top line might be “C\*l Diod\*\*”. The bottom line appears to be Gottingen. Possibly a classroom demonstrator from the University of Gottingen. ---
**Author:** ![Bonum\_Legatum](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bonum_legatum/32/6183_2.png) [@Bonum\_Legatum](https://boards.straightdope.com/u/Bonum_Legatum)\ **Post date:** [November 8, 2021, 11:59am UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/10 "2021-11-08T11:59:47Z")
Note that the current from one of the slip rings is passed up to the component in the center by a coil spring. So there is something going on electrically, and whatever that is - it needs the component to rotate along with the motor… The coil spring indicates that something will be moving. This might be an electrical governor, a rheostat, to automatically control the speed of the rotor. On the other hand, it might be some form of adjustable capacitor - to adjust the inductive/capacitance characteristic (the “L/C”) of the rotor. ---
**Author:** ![Marvin\_the\_Martian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/marvin_the_martian/32/2898_2.png) [@Marvin\_the\_Martian](https://boards.straightdope.com/u/Marvin_the_Martian)\ **Post date:** [November 8, 2021, 5:34pm UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/11 "2021-11-08T17:34:09Z")
I think the name is Carl Diederichs. From the _Special catalogue of the joint exhibition of German mechanicians and opticians_ at the Exposition Universelle Internationale de 1900: [![Imgur](https://i.imgur.com/4iHF4fp.png "imgur.com") ](https://imgur.com/4iHF4fp) So “Physical Demonstrating Appliance” is a very strong possibility. Another area Diederichs was involved in was “psychological instruments”. From _Wilhelm Wundt in History: The Making of a Scientific Psychology_: [![Imgur](https://i.imgur.com/1CCZIQS.png "imgur.com") ](https://imgur.com/1CCZIQS) Unfortunately the book cuts off before it says what Diederichs’ main business was. I sure hope that the picture isn’t some sort of psychological instrument (all I can think of is “Is it safe?”)… ---
**Author:** ![Marvin\_the\_Martian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/marvin_the_martian/32/2898_2.png) [@Marvin\_the\_Martian](https://boards.straightdope.com/u/Marvin_the_Martian)\ **Post date:** [November 8, 2021, 5:57pm UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/12 "2021-11-08T17:57:26Z")
I found it! From _Photographic Album on Psychological Instruments. 59 Photographs._ (Titchener, Edward B. 1895): [![](https://digilib.mpiwg-berlin.mpg.de/digitallibrary/servlet/Scaler?pn=23&ws=1.5&fn=/permanent/vlp/lit13651/pages&dw=1232&dh=802) ](https://digilib.mpiwg-berlin.mpg.de/digitallibrary/servlet/Scaler?pn=23&ws=1.5&fn=/permanent/vlp/lit13651/pages&dw=1232&dh=802) The title is “Helmholtz’s Electromagnetic Rotary Apparatus” with handwritten description: [![](https://digilib.mpiwg-berlin.mpg.de/digitallibrary/servlet/Scaler?pn=24&ws=1.5&fn=/permanent/vlp/lit13651/pages&dw=1232&dh=802) ](https://digilib.mpiwg-berlin.mpg.de/digitallibrary/servlet/Scaler?pn=24&ws=1.5&fn=/permanent/vlp/lit13651/pages&dw=1232&dh=802) [![](https://digilib.mpiwg-berlin.mpg.de/digitallibrary/servlet/Scaler?pn=25&ws=1.5&fn=/permanent/vlp/lit13651/pages&dw=1232&dh=802) ](https://digilib.mpiwg-berlin.mpg.de/digitallibrary/servlet/Scaler?pn=25&ws=1.5&fn=/permanent/vlp/lit13651/pages&dw=1232&dh=802) ---
**Author:** ![QuickSilver](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quicksilver/32/7832_2.png) [@QuickSilver](https://boards.straightdope.com/u/QuickSilver)\ **Post date:** [November 8, 2021, 6:11pm UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/13 "2021-11-08T18:11:44Z")
I was sure it was the first [hyperbolic-ion-encabulator](https://boards.straightdope.com/t/the-all-new-hyperbolic-ion-encabulator/953556), ---
**Author:** ![Marvin\_the\_Martian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/marvin_the_martian/32/2898_2.png) [@Marvin\_the\_Martian](https://boards.straightdope.com/u/Marvin_the_Martian)\ **Post date:** [November 8, 2021, 6:18pm UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/14 "2021-11-08T18:18:03Z")
More information from the Spindler & Hoyer (successor to Carl Diederichs firm) _1921 Apparate für psychologische Untersuchungen_ catalog: [![Imgur](https://i.imgur.com/p6g6XZi.png "imgur.com") ](https://imgur.com/p6g6XZi) [![Imgur](https://i.imgur.com/xY6r3W5.png "imgur.com") ](https://imgur.com/xY6r3W5) [![Imgur](https://i.imgur.com/oBsOpqc.png "imgur.com") ](https://imgur.com/oBsOpqc) ---
**Author:** ![Marvin\_the\_Martian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/marvin_the_martian/32/2898_2.png) [@Marvin\_the\_Martian](https://boards.straightdope.com/u/Marvin_the_Martian)\ **Post date:** [November 8, 2021, 6:58pm UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/15 "2021-11-08T18:58:45Z")
OK, here’s the answer (in English), courtesy of the Musems of the History of Psychological Instrumentation at Montclair State University ([Helmholtz' electromagnetic rotator](http://tomperera.com/psychology_museum/x_016.htm)): [![Imgur](https://i.imgur.com/uAHlcn7.png "imgur.com") ](https://imgur.com/uAHlcn7) An instrument used in the study of color perception. Well that killed the morning… ---
**Author:** ![pjd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pjd/32/3009_2.png) [@pjd](https://boards.straightdope.com/u/pjd)\ **Post date:** [November 8, 2021, 7:54pm UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/16 "2021-11-08T19:54:39Z")
@Marvin_the_Martian Genius. Respect due. ---
**Author:** ![Hatchie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hatchie/32/3983_2.png) [@Hatchie](https://boards.straightdope.com/u/Hatchie)\ **Post date:** [November 8, 2021, 10:23pm UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/17 "2021-11-08T22:23:28Z")
Holy moley, I would not have guessed that. Thank you Marvin for expending way too much effort on nailing (and I do say ‘nailed’ without the slightest fear of contradiction) a query I had marginal interest at best in pinning down. The English blurb says it was used for color mixing. Seems a bit complicated way of doing it, but if you had one of these on your coffee table, you’d have a sure-fire conversation starter, so I guess “social lubricant” could be an alternate apt description. ---
**Author:** ![Hatchie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hatchie/32/3983_2.png) [@Hatchie](https://boards.straightdope.com/u/Hatchie)\ **Post date:** [November 8, 2021, 10:42pm UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/18 "2021-11-08T22:42:17Z")
Bonus points: If you Google “Helmholtz’s Electromagnetic Rotary Apparatus”, this comes up [![Imgur](https://i.imgur.com/cbNnOau.jpeg "imgur.com") ](https://imgur.com/cbNnOau) which makes this sort of a Factual Twofer. ---
**Author:** ![Marvin\_the\_Martian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/marvin_the_martian/32/2898_2.png) [@Marvin\_the\_Martian](https://boards.straightdope.com/u/Marvin_the_Martian)\ **Post date:** [November 8, 2021, 11:22pm UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/19 "2021-11-08T23:22:38Z")
> [@Hatchie](#): > > Holy moley, I would not have guessed that. Thank you Marvin for expending way too much effort on nailing (and I do say ‘nailed’ without the slightest fear of contradiction) a query I had marginal interest at best in pinning down. De nada. Just testing the limits of my Google-fu. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [November 9, 2021, 6:01am UTC](https://boards.straightdope.com/t/identify-this-device-please/953876/20 "2021-11-09T06:01:11Z")
I’d have guessed it was an early prototype of Michaelson and Morley’s inteferometer. (ETA: Has anyone figured out why this was found in a cookbook?) [Next page](https://boards.straightdope.com/t/identify-this-device-please/953876.md?page=2)