I would like to use an old Dietzgen Transit to locate the property corners on the ranch. The transit appears to me to have been adjusted to compensate for a magnetic declination of about 182° W. The declination at my location is 12° 38' E so I would like to readjust the transit zero degrees or to the correct setting for my location. So far I have not been able to find a way to do this. The instrument only has an upper motion locking knob, a lower motion locking lever and a ng vernier adjusting knob. I have removed the glass cover and tried to move the outer ring without success. I even loosened the four screws securing the compass face, also without success.
Is this adjustment something I have to have done at a repair facility or just something I am not seeing and can be done by myself?
Any suggestions would be greatly appreciated.
It might help to show a picture(s)
Now is the time for all good men to come to the aid of their country. Typing class 9th grade!
Thanks for the reply. It is a fairly complicated process to attach pictures on this forum but I think I have it figured out and will give it a try. There is a typo in the original post. My transit looks to me like it has been adjusted to compensate for a magnetic declination of 13° 40' W. If I am successful in attaching some pictures, you may be able to confirm what I think my instrument has been adjusted for and hopefully allow you to help me return it to a zero setting. In case the pictures do not load directly, the links to them are as follows:
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Second picture of transit:
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Magnetic declination changes over time, and it's also different from one place to another. Using magnetic bearings to find monuments is not likely to give good results.
What you need is a survey drawing showing the distances and directions between the corners. If you can find two of them, you can then find the others by laying out the angles with your Dietzgen.
You can post images directly until you've had a few moderated posts. You should be able to post images now.
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Thank you this is very helpful and tells me that I am at least able to bring the compass circle back to zero. The manual says that I can rotate the circle back to zero or the correct declinataion by "turning the capstan head pinion near the S or W mark". As far as I can tell this Diezgen transit does not have any kind of pinion near the S or W mark. I have removed the glass and tried to gently move the circle manually but without success.
in answer to the post by Rplumb314: Thank you for the information. I use the NOAA website to calculate the declination for my location and my old parcel map and record of survey was done using quadrant bearing notation. This and the fact that I have two corner pins located will make it fairly easy to locate the other corners that are buried by over fifty years of duff.
Adjusting the compass ring on this old Dietzgen to zero or to my local declination would just make life a little easier on this 82 year old mind as I dragging this 30 lb instrument around the ranch.
I do have a lighter and more precise Wild T0 theodolite with an intergral compass that would be much handier but the needle refuses to come to rest at the same reading and is therefore not very trustworthy. This is slightly depressing since it is a memento from my first and only survey job and very easier to use on this short range stuff.
Thanks to all for the help. God willing, I will try again tomorrow to post pictures.
Here is a picture of the compass and I read it to be adjusted for a W declination similar to the picture posted by Norman
An old ex empoyee of mine dropped by while I was posting this and looked at the picture. When he stopped laughing he reminded me that I had used this old transit on a US Forest Service job 35 years ago and pointed out that it is set for a E declination. I just have to correct it by a couple of degrees if the two of us can figure out how I did it. He's still a youngster at 67 so he may see something I'm missing.
@dinasnore Or leave it where it is and just add or subtract 2 degrees from your reading.
I thought about that and will probably do that but would be convenient to just adjust it and not have to do some more calculations with this 82 year old mind. The scariest part of this discussion is before he left I confessed to him that I still try to visualize the compass headings and still see it reading for a W magnetic declination. He suggested I give it a rest for few days. He could be right but it might take more than a few days.
I've attached the only thing on the transit that I don't know the function of but it does not like anything that would allow me to adjust the declination arc.
BTW, you didn't weigh in on what the transit is adjusted for at the present. Let me know if you have an opinion after seeing the picture.
Picture of the beast in question. BTW this and my other old antiquated survey equipment is going into a trust and the trustee will be posting the items on this forum to be given to someone that has an interest in having them.
Once you do find the adjustment mechanism you will smack yourself!
Now is the time for all good men to come to the aid of their country. Typing class 9th grade!
Don't have to smack myself, still have a couple of younger friends that frequently do it for me. If you would like to speed up the smacking process perhaps you could post a clue as to where to look on this old beast.
My guess would be a small screw underneath the compass.
Now is the time for all good men to come to the aid of their country. Typing class 9th grade!
@dinasnore I had alwaye thought that the item next to and slightly overhanging the level vial was for protecting the vials.
@dinasnore I would call that West Declination. If you were in Virginia that current adjustment would allow you to read N 14d W on the outer dial while the compass needle was pointing to magnetic north and N on the inner dial.The N on the outer dial would be pointing to your adjusted north. Switch the outer N to the left of the inner N 14 degrees and you now could use this compass in Oregon or Washington with its East Declination.
I agree with you but if you look at the page out of a manual, figure 2 is supposed to be an illustration of a transit adjusted for a W declinatio. Unless my eyes decieve me the N on the outer circle is clearly on the left of N on the inner circle. If the illustration is correct, my transit that has the outer circle clearly to the right of N on the inner circle, is adjuste for an E declination.
The problem that raises is if the needle is being pulled East, it is gaining degrees so why would it make sense to rotate the outer circle clockwise to the right of N and add even more degrees to the reading? My reasoning tells me the outer circle needs to rotate counter clockwise as you describe.
What am I missing here guys?
@dinasnore Perhaps we are making the mistake assuming the inner circle is representative of magnetic direction. If you make the outer circle the magnetic north then your compass has an East declination. Looking closer the inner circle is only annotated to 40 degrees.