Vintage Stern-Gerlach device

After going through an old storage room, someone here at Saint A’s came upon a Stern-Gerlach experiment in a box (disassembled) made by the old Ealing Corp. which, at one time, was in South Natick, MA, but is now in California. They seem to be solely an optical company these days so I have little hope that they will be able to find a set of instructions (since there wasn’t one in the box). Has anyone out there seen one of these things and, if so, do you have any idea of how to put it together?

Update: Well, while a helpful guy at Ealing could find no information about such a device going back to 1969, my colleague Jeff found the instructions tucked away in the filing cabinet! As it turns out, the experiment was made in the mid-1960s (first manual apparently appeared in 1966) and was developed by a Melvin Daybell at New Mexico State University. It’s possible, then, that it was a custom job (which would explain why Ealing didn’t find it in any of their old catalogs), but does not explain how it came into our possession. Unfortunately, the faculty member who most likely obtained it for us (likely in the ’60s since his name appears on something in the folder dated 1967) has since passed away so we may never know (particularly since there is no Melvin Daybell presently at NMSU).

Update II:…and that is because Melvin Daybell is at USC!


27 thoughts on “Vintage Stern-Gerlach device

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  1. Mel Daybell posted this over at my old blog just last week. I need to send him an e-mail thanking him:

    “Ealing made a modified version of my Stern-Gerlach apparatus as a kit for a few years. There was a manual describing my original version, not much different. Might try Prof. Liefeld (NMSU, retired but active) and see if they still have some. Somebody at one of the Pennsylvania university had a lot of experience with the Ealing machine, and wrote up some notes he was going to publish, but didn’t.
    Mel Daybell”

  2. Still trying to get my hands on them! I contacted this Liefeld guy recently but have not heard back. I’m not even sure we have all the parts which is why I am trying to get my hands on some stuff. The folks at Ealing Corp., which used to sell these kits, did not have an old manual in their archives. We’re looking through our own archives (i.e. closets, boxes under lab benches, etc.) but haven’t found it yet.

  3. I have a manual titled “Construction Notes and Drawings for the New Mexico State University Stern Gerlach Apparatus”. It looks to be complete including a list of materials, and is just as the title describes. At one time we even had the kit, which looked very much like your photo. But after several moves, little remains of it. We are considering resurrecting the experiment.
    Would be happy to provide a scan.

    Jim Kelley
    Physics and Astronomy
    UC Irvine

    1. Dear Mr. Kelley,

      We would love to have a scan of the document “Construction Notes and Drawings for the New Mexico State University Stern Gerlach Apparatus” if you are willing to provide one. We are preparing to attempt construction of one of these here at the Naval Academy and while I have Prof. Daybell’s 1966 article I have been unable to find exactly this document (mentioned in footnote 2).

      1. If you still need it, I’ve recently found a copy of my manual. I’ve scanned the instruction part, and also made a few paper copies of the drawings. (The drawings were too large for our scanner; will try to get them scanned some day.) The instruction scan is posted on my wife’s iDisk, and will be there until the iDisk dies on June 30, 2012. The link will download a PDF.

        If you email a USPS address to, I can send you a copy of the drawings.

        Mel Daybell

      2. I was able to locate the image files and send them to the person who requested them. Though, I did not receive confirmation that they were received.

      3. So I never got around to starting a listserv, but I did have a student scan all the information we have. I’m just not sure where to put it (the files are huge).

        We are definitely missing a few pieces and we don’t have a machine shop to make new ones. But I’m still interested in getting this thing running again one of these days.

        I’ve been insanely busy (the joys of being department chair) and, honestly, I’m forgetful (I’m a theorist so…). So, my apologies for not being more proactive about this.

        Ian (quantummoxie)

  4. Well, it seems interest in this is still there. I will attempt to locate all our material (it got moved again this summer) and use Jim’s information to see if we have all the pieces. If I have major questions, I’ll consult Mel. Perhaps we should get some sort of user group list started or something. This could be fun!

  5. I’m currently working on a stern-gerlach apparatus at the university I’m attending, and we’re stuck on the construction of the hot-wire detector. If that model has a hot wire detector, perhaps you could email me a copy of that section of the instruction manual you have in your posession? My email is Thanks for the help!

  6. We also have an old Ealing Daybell apparatus in our LabCourse. I managed to get it working a view weeks ago! Will have the first course with students soon. Have a brief description of the original apparatus.

      1. Hi Mel,

        You know, I never got around to starting one. In fact, now that I think about it, I have no idea how to. But I’m sure I can figure it out.

        I’ve been insanely busy (the joys of being department chair) and, honestly, I’m forgetful (I’m a theorist so…).

        Ian (quantummoxie)

    1. Dear Mel & Dorothy,

      we are still using the device in our lab course successfully. The students did three quite nice experiments this semester. I have
      some trouble with the oven, however. The wire is broken on one
      side of the oven so I had to put a short to ground and use the
      oven itself as electrical pole. Do you remember how the heating
      is done? I tried some Tungsten or Konstantan wire (instead) but the specific resistance is too low. In total about 1Ohm is needed for the
      heating! Do you know how the heating was made originally?

      Many thanks, Klaus

      1. Thanks for your notes. Always good to hear we did some good at several schools.

        Regarding the oven heater: by now you will have seen the instructions for building this, in my original manual. It is in the “Construction notes and drawings” section, part II Notes, step 18.

        The #24 nichrome wire will have a resistance of about 1.6 ohms/foot. Wrap it on a #50 drill bit. Coat it with Alundum cement, and heat it to dry it out. See step 18 for all the details.


      2. I am so glad that this page is turning out to be a meeting point for people to discuss this experiment. I apologize for not being more pro-active about this over the past few years, but my only excuse (well, the only one that makes any sense) is that I’m really a theorist. Nevertheless, I have ventured into the lab (and nothing has broken yet) to start doing some optical experiments. My plan is to eventually get our SG experiment up and working again fairly soon. We are missing a few pieces but I haven’t quite figured out which ones yet. I had a student working on it, but he graduated. I’m hoping to get another one on it here soon and I have a couple of colleagues who are mildly interested in seeing it revived.

        So thanks for the assistance with the notes Mel! And thanks to everyone for the input on how they are running their setups!

    2. Dear Mel,

      when looking to the manual you posted I saw that the resolution as well as signal/noise of your data (Fig.8) seems to be much better than my results
      Look at Fig. 7 (Text is German, but Plot will do), lines are fits to the data. Do you remeber what influences resolution and noise most, thus what should I check first?
      I do not know the magnetic field precisely, I do have a table with an
      old measurement (guess still from the time the apparatus was at Bonn), thats it. It seems as if the field in indeed somewhat lower
      (5-10%) which is possible as additional gaps in the magnet joke
      might cause this order of reduction. Is there a trick to measure the field? I tried a hall probe, but even a 1mm thick probe is too thick,
      given the inhomogeneity of the B field. Playing tricks like turning the probe around and measureing several times did also not work out.

      Many thanks, regards, Klaus

  7. Dear Folks,

    For some reason my mind wandering tonight in the direction of some of the things I did when I was a student. It occurred to me that I’ve never looked up Ealing Corp since the time I worked there around 1969. So I Googled ‘Ealing’ and then finer and finer restrictions but did not really find it.

    Then, I added ‘Stern’ to the search — and found this list. The reason I added ‘Stern’ was because I wrote the user guide for the Stern-Gerlach apparatus for Ealing! Including the error analysis which I had learned a few years before and had never used since that time.

    So I’m very pleased to read this discussion.

    Actually, at the time I was writing the user guide I thought that this was a rather poor experiment for students. I felt the trouble with it was that there was always the one single value that was the target. I felt that students ought to be given a ‘mystery’ object and try to find out its properties — or something like that.

    Anyway, again, glad to meet you all. I haven’t done physics for a long time but it’s still one of my favorite reads.

    -yoram gelman

    1. Hello Yoram! So glad you joined the conversation! To be completely honest with you, it turns out we may have lost some of the crucial pieces of the apparatus over the years. Given that I can essentially do a perfectly analogous demonstration with photons, I haven’t pursued fixing it. Perhaps someone else on here has actually gotten theirs to work? We have the manuals and the boxes, but some pieces are missing. Given how long we have had it, it has survived multiple building changes so who knows where the parts could be.

      1. I would love to have a copy of that manual !

        Mel Daybell, Vintage Physics Professor (emeritus) University of Southern California
        Box 300, Shaver Lake, CA 93664

        (I developed the original of that apparatus under an NSF grant while a young physics professor at New Mexico State University in 1965. It took first prize at the apparatus competition at the AAPT annual meeting in New York. As required by the grant, I found a commercial vendor for it, and worked with T. Wally Williams at Ealing. They made some improvements in design before selling a kit version. I was following in the spirit of the “Apparatus Drawings Project” of the American Institute of Physics.)

      2. I think a former student of mine digitized it. I’ll see if I can dig it up. Maybe I’ll post it. I imagine that any copyright issues are long gone.

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