Shawn, the above post by me?ÿ about 6 circle settings; I gave you what the book says to use but I never set the 10 seconds on the 1st set. I always use around 30 seconds.
That's great information, John. I really appreciate it.
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The T2 (I think) was what I used in surveying courses in '81-'82.?ÿ I got a T16 about 6 years ago here and used it to layout about 1000' of gently curving 8" waterline trench and a new concrete roadway about the same length (both on private property).?ÿ Cool times - now I'm stuck with the S6 and some old GPS equipment to get that stuff done.?ÿ But your post made me break out the T16 today, turn all the knobs, apply some strategic penetrating oil and fiddle with a few tiny screws.
@thebionicman I was just picking. I was referring to the western regional conference in Las Vegas last week. And yes, he was there. Lol. I understand there were three baptisms after the altar call.
@shawn-billings In addition, buying 4 new trucks, and a Wang Labs 720C computer/input-output writer (for $11,500), starting out in private practice in1972, was quite a bit for 2 poor country boys who had no network of contacts. Fortunately, Disney World had just opened and the Orlando area was beginning to boom, so we never ran out of work.
@john-nolton Exactly. Range of motion was the killer when the pole had to be removed for a tall monument.
These are tables showing the plate settings for observations (both Parkhurst and Wild T3). The idea is make observations on different parts of the plate?ÿ
The table was taken from Special Publication No. 47 available for free download through the ??Publications? link on the NGS site. See below:
https://geodesy.noaa.gov/library/pdfs/Special_Publication_No_247.pdf
This is a great 1959 manual on not only triangulation but related activities like baseline measurement, leveling, astronomic observations as well as reduction-to-center and eccentric observations. There is a note therein remarking about some interesting develops using laser technology with possible future application.
For those not interested in the old methods, there are a good number of illustrations, figures and forms to solve problems using logarithms.?ÿ
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@shawn-billings?ÿ ?ÿShawn I can help you with turning angles with a Wild T2.?ÿ We will only talk about one set of D&R and how to record and mean.
First a little hint; if using in day time use an umbrella (useful but not required) plus I always like to use the battery box ( that way you always have uniform light on the scales; useful but not required). There are more but this will get you started. Now if you are going to turn more that one set (here one set is a Direct and Reverse to your back site and a Direct and reverse to your fore site). You will have to get the circle setting from one place or another. One place to get them is from NGS pub. "Specifications to Support Classification, Standards of Accuracy, and General Specifications of Geodetic Control Surveys (July 1975 and revised June 1980) NGS internet site. So now your inst. is set up (of course it is in adjustment according to the manual) and leveled.
You look at your back site and set something positive on the plate around 30". This is done with the circle setting knob and your micrometer knob.Look at the back site and bring to cross hairs on the target (always remember that your last movement of the horizontal knob is clockwise), bring the lines into coincidence and read the circle.
D?ÿ 0-0-30?ÿ (this value is +/- say 10 sec, it does not have to be exactly 30") Turn your inst. clockwise to you next target. Site the target and make sure the last motion of the horizontal motion is clockwise. Read the circle the same way as above.
D 45-23-56?ÿ (here if you want you can estimate to 0.1 seconds). Now you plunge the scope (this is where you turn the scope on its vertical axis 180 deg. this will make the objective end of the scope facing you without touching the horizontal motion YET. Now you turn the scope counter clockwise and point back to you fore site?ÿ and read the scale. R 225-23-52. then you turn the scope (still turning counterclockwise back to your rear site and read the scale R 180 00 22. If a recording book it will look like this.
D 0-0-30
R 180 00 22
D 45 23 56
R 225 23 52
I agree that the recording book will look like that.
However observationally the following will take place at the instrument:
1. Point on first target in telescope direct (D) setting the plate to close to 0d 0m 0s
2. Make observations to targets in D
3. Flip telescope ?ÿto be in Reverse (R) read value on last target.
4. Return to first target in R which should be within a few seconds of 180d 0m 0s.
5. With telescope still locked (and in R) reset plate to 225d 01m 0s.
6. Make observations in R.
Perhaps it is simpler just to show what the values will be at the first target???ÿ
When a direct pointing (D) is followed by a telescope reverse pointing (R) the telescope was flipped at the last target. Note how the plate setting change by 45d in the four-position set. The minutes are changed as a blunder check. The values shown as 0 seconds are actually only near zero.
?ÿ ?ÿ0d 0m 0s D
180d 0m 0s R
225d 01m 0s R
?ÿ045d 01m 0s D
090d 02m 0s D
270d 02m 0s R
315d 03m 0s R
135 03m 0s ?ÿ D?ÿ
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@geeoddmike?ÿ Please note that the NGS pub. SP #247 you quote (on page 193 and other pages) spell the word
base line?ÿ not baseline
Also note that if you want Wild T2 (or any other 10 minute micrometer drum instrument) you can go to "Specifications to Support Classification, Standards of Accuracy, and General Specifications of Geodetic Control Surveys" page 8 as I have posted.
Since you are very good at posting references (like you did above from SP 247) maybe you could post the page 8 I made reference to. Thanks in advance.
JOHN NOLTON
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@geeoddmike?ÿ I guess I did not explain it good enough or you did not understand my wording.
I am giving ONE angle and how to record the D&R's for just ONE angle. Also note that you never set?ÿ ?ÿZero (your first angle Direct setting) on the plate on on any directional instrument.
But Shawn, you're going backwards in technology.. ?????ÿ
Brings back old memories.?ÿ You inspired me.?ÿ In the Army, we had T-2's graduated in mils instead of degrees.?ÿ I think it was a NATO thing.?ÿ Meters and mils.?ÿ So every country was on the same page.
Three sets of D&R readings, throw out the worst set.?ÿ Superb optics.
Later in life in private practice, before the Geodimeter days, we used one with a top mount Topcon edm.?ÿ I think it was a DM-S2 or 3 variant.?ÿ ?ÿWhat is yours?
I hope no one was confused by my use of ??baseline? rather than ??base line.? Having managed to get my link correct ;> I did not bother to check for this nomenclature. I still cannot get my spellchecker to accept ??data sheet? for ??datasheet.?
As for posting your preferred reference for plate settings, the document you cite seems unavailable on either the NGS or FGCS sites. You reference a valid document and I did find it via Google. I will contact the NGS regarding the omission.
@geeoddmike?ÿ ?ÿIf you cannot find that publication I can mail you mine and you can copy it, if you want. It's 46 pages long.
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