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Azimuth mark with its own RM? - and USACE disks


TillaMurphs

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We found an Azimuth mark with its own reference mark. Its reference mark is not listed in the NGS database.

 

The azimuth mark was for POLLYWOG RESET (OA0935). At 11.8 feet west of the azimuth mark there is a disk. The disk is a U.S. Army Corps of Engineers station disk that appears to have been pressed into service as a reference mark disk. It has an obviously hand-scribed arrow pointing towards the azimuth mark (and a sideways “V” letter stamp was used for the point of the arrow).

The azimuth mark's reference mark disk is stamped: POLLOYG A. R.M. 2 and looks like THIS and THIS.

 

This leads us to 4 questions:

  1. How often do azimuth marks have their own reference marks (we have never come across one).
    .
  2. Is there any way to find out information about U.S. Army Corps of Engineers (USACE) disks?
    .
  3. Why would the station disk and the azimuth mark disk be USCGS disks and the azimuth mark reference mark disk be a USACE disk?
    .
  4. Why the hand-scribing of the arrow, and possibly the triangle, on the USACE disk?

 

 

Thanks for any help!

 

Bonus question #5 for extra credit:

 

What do you suppose these things are:

They were on the ground right next to the station and they survived a major forest fire that swept that through the area. They are 2.75 inches long and were lying exactly as seen in the photo. We first thought they might be battery cores. However, when we got home and measured, we found out they were too long for that.

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Part I. I would suspect AZ Marks with RM's would be rare. Occasionally when a station is lost, or for other site reasons and RM or AZ Mark is used as a station itself. In that case for an Azimuth mark it would make sense to set RM's to it. It might have just been considered a nice monument to use as a station in a later survey and thus elevate it's status.

 

Part II. I think your idea about battery posts is the most likely, there are or have been all kinds of battery sizes. For example the 4 cells inside a 6v lantern battery might be longer than D cells, but I would not expect them to have the little cap.

 

- jerry

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Great photos!

 

I really like the old compass. I just have a guess on the bonus question. -They look as though they would have been used as containers of some sort. For what? Pencils, matches, camping supplies of some sort? or batteries.-

 

Do not have a clue for the RM for the Azimuth mark.... Benchmark hunters come up with some really interesting ones, don't we?

 

Shirley~

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I'm with Jerry. Two of the carbon rods out of a carbon-zinc-ammoniac old-fashioned lantern battery. And I think they might have metal caps on them in order to have something to solder the connecting wires to.

 

A secondary guess would be carbon electrodes for an arc lamp or similar device.

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Fascinating find(s)! Our guesses on questions 1, 3, and 4 are

 

1. Pretty scarce, we'd suppose; we've never seen an instance of a disk specifically set as an azimuth mark and given a reference mark. Obviously, there are many instances of sets of triangulation stations, each with two RMS, where the two main stations are each other's azimuth marks. That's something else.

 

3. We imagine that the USACE disk was there already when the azimuth mark was set, and so came in handy as a reference, and

 

4. could only be marked by hand in the field.

 

Great log!

 

Cheers,

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Due to some bizarre myth, there are a lot of videos on youtube which dissect 6 volt lantern batteries. They show that it contains 4 cells (not surprising) about the diameter of a D cell, perhaps larger, and longer. So I still say what you found is consistent. This saves us from having to repeat the exercise.

 

This is one of them:

 

 

 

- jlw

Edited by jwahl
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Fascinating find(s)! Our guesses on questions 1, 3, and 4 are

 

1. Pretty scarce, we'd suppose; we've never seen an instance of a disk specifically set as an azimuth mark and given a reference mark. Obviously, there are many instances of sets of triangulation stations, each with two RMS, where the two main stations are each other's azimuth marks. That's something else.

 

3. We imagine that the USACE disk was there already when the azimuth mark was set, and so came in handy as a reference, and

 

4. could only be marked by hand in the field.

 

Great log!

 

Cheers,

 

I agree with all of the above!

 

As for the strange rods, I have seen plenty of them on mountaintops here in Arizona, and have always assumed they were battery cores.

 

87cdaa6d-634c-457b-8a38-4eca59323e57.jpg

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Thanks - to all of you for your input thus far.

 

3. We imagine that the USACE disk was there already when the azimuth mark was set, and so came in handy as a reference, and

The RM was stamped with an approximate spelling of Pollywog which is 4 miles away. Since there is no other stamping on the disk, if the disk was already set before being used as an RM for Pollywog's Azimuth mark, it would have to have been originally set with no stamping on it.

 

Due to some bizarre myth, there are a lot of videos on youtube which dissect 6 volt lantern batteries. They show that it contains 4 cells (not surprising) about the diameter of a D cell, perhaps larger, and longer. So I still say what you found is consistent. This saves us from having to repeat the exercise.

- jlw

As for the strange rods, I have seen plenty of them on mountaintops here in Arizona, and have always assumed they were battery cores.

Wow – now that is some helpful research that you two have done – thanks. I bet this is the first time there has ever been a detailed discussion of battery internals in the Benchmarking forum :o . I am going to have to go to the hardware store and measure a lantern battery and see if the height is consistent with the length of the cores that we saw.

 

Bizarre. Now we have battery cores on mountaintops from Arizona to Oregon.

Would surveyors of old have a specific need for batteries on summit triangulation stations? Would such surveyors be likely to leave the batteries on the summit rather than packing them out?

Or… are aliens somehow involved? …

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That last pic is the center rod on what used to be a standard size "ignition cell". Those are about 8 ins. tall and 3.5-3 in. diameter and were used for starting model airplane glo-plug engines. I used them to power a home phone system and dozens of other experiments when I was a kid. They were 1.55 volt single cells, but I also remember they were packaged into a 4 cell format in one tin enclosure about a foot long with a handle and were used in electric fence chargers. That would have been a form readily available in hardware stores between 1940 and 1990.

 

Ignition cell example However these are faked up but that's what they looked like mostly.

 

and here, looks like these might still be for sale.

 

Ignition "6" cells

 

Almost any station that had a light for a signal would have had batteries to run them. The NGS picture is a perfect example. There is also a larger dimension lantern battery, horizontally with screw posts and the large reflector light screwed right onto the battery.

 

1231 Lantern Battery

 

Note that spec sheet says it contained 2 rows of 4 "F" sized cells. I suspect that the regular lantern battery cells are thus "F" sized. I have never heard that one before. More research. I find a lot of "F" sized rechargeables referred to as "long D" in some ads.

 

This link, if you get it to work, shows a page that lists D F and G sized carbon zinc cells before the "6" which I think is the ignition cell. No pictures though.

 

Carbon Zinc types

 

LED's would have been great if they existed then.

 

One more link about "F" cells. Note that the size 6 pictured is not a typical type. The real ignition cell has a single large carbon post about 3/4 in. diameter and 6.5 in. long. as shown in the previous post. Because these types are no longer readily available, people are faking up replicas with all kinds of internals.

 

Apparently the "6" sized was also used in old phone systems inside the crank wall phone boxes. I can vaguely recall from my grandmothers house on the farm.

 

More

 

Note to self: interesting how many of these types which were once ubiquitous, are now long gone from the market.

 

PS I remember that the long lantern battery format similar to the 1231 came in either a 6 volt (parallel 2 rows of 4 cells in series) or 12 volt (all in series) apparently a type 732. All the "Lantern" types are still sold today.

 

<Nostalgia alert off.>

Edited by jwahl
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Signal lamps were used so that longer triangulation shots could be sighted accurately at night. Here's a sample photo I found in the NGS photo Library:

Note that spec sheet says it contained 2 rows of 4 "F" sized cells. I suspect that the regular lantern battery cells are thus "F" sized. I have never heard that one before. More research. I find a lot of "F" sized rechargeables referred to as "long D" in some ads.

 

This link, if you get it to work, shows a page that lists D F and G sized carbon zinc cells before the "6" which I think is the ignition cell. No pictures though.

<Nostalgia alert off.>

 

southpawaz and jwahl (and AZcachemeister from an earlier post),

 

You have really disappointed me. You seem to have completely solved my mystery and now I have to abandon my alien conspiracy theory - drat. :ph34r:

 

southpawaz's photo is very illustrative (although it looks like they have not quite finished wiring up the inter-battery connections). Were the lights used at night because it was easier to pinpoint a distant position at night with a light than with any other method during daylight hours?

 

jwahl - thanks for the VERY in-depth battery research. (BTW: nostalgia = good). (It took me a while to reply to this thread because I needed to read through all your great info.)

I think the rods that we found must have been from something similar to the F-cell. The top end of the rods appeared to have a "cap" rather than a thread to accept a screw-in fitting such as in southpawaz’s second photo.

 

We will keep our eyes out for more battery cores during future benchmark searches.

Edited by TillaMurphs
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Were the lights used at night because it was easier to pinpoint a distant position at night with a light than with any other method during daylight hours?

 

We will keep our eyes out for more battery cores during future benchmark searches.

 

Partly, but long sightings (as I understand it) were done at night to avoid the shimmering effect of air currents during the heat of the day. This is most important here in the desert southwest, and indeed, you would probably want to do this work at night even if it made no difference at all! :ph34r:

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Similar comment. What we called 'heat waves' limit visibility over long lines. If you're in mountainous country where your line of sight may be some distance above the ground you may be able to see large target sights up to 12 miles or so, but where lines of sight are along the ground it is hard to see or to get accurate angles. Generally the air settles down a few hour into the night and one will get much better results under those type of conditions.

 

I would bet that 95% of all C&GS (NGS) work was done at night to lights set over the station. Usually on whatever stand or tower was erected there for the instrument when occupied. Some data sheets note the height of the light, and some note an eccentric light in rare cases. A light right on the station mark might have been done for a short site such as to an azimuth mark.

 

There are quite a few pictures on the NGS site. You will also find lots of instructions on lights and so forth in various C&GS publications and Manuals on triangulation.

Edited by jwahl
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Similar comment. What we called 'heat waves' limit visibility over long lines. If you're in mountainous country where your line of sight may be some distance above the ground you may be able to see large target sights up to 12 miles or so, but where lines of sight are along the ground it is hard to see or to get accurate angles. Generally the air settles down a few hour into the night and one will get much better results under those type of conditions.

 

I would bet that 95% of all C&GS (NGS) work was done at night to lights set over the station. Usually on whatever stand or tower was erected there for the instrument when occupied. Some data sheets note the height of the light, and some note an eccentric light in rare cases. A light right on the station mark might have been done for a short site such as to an azimuth mark.

 

There are quite a few pictures on the NGS site. You will also find lots of instructions on lights and so forth in various C&GS publications and Manuals on triangulation.

You'd be surprised at the distances they measured even back in the 19th century.

 

I've looked carefully at the first order triangulation done in New England (where the distances were the longest) which were done mostly in the 1860s and found the following as some of the longest (km and mi rounded to whole units):

 

Ragged (ME) to Pleasant (ME) - 135 km (84 mi)

Gunstock (NH) to Wachusett (MA) - 122 km (76 mi)

Gunstock (NH) to Thompson (MA) - 113 km (70 mi)

Ragged (ME) to Blue (ME) - 107 km (66 mi)

Humpback (ME) to Ragged (ME) - 110 km (68 mi)

Monadnock (NH) to Bald (CT) - 99 km (62 mi)

Thompson (MA) to Wachusett (MA) - 96 km (60 mi)

Gunstock (NH) to Monadnock (NH) - 95 km (59 mi)

Harris (ME) to Blue (ME) - 94 km (58 mi)

Unconnunoc (NH) to Blue Hill (MA) - 94 km (58 mi)

Blue (ME) to Washington (NH) - 92 km (57 mi)

 

Pretty amazing.

Edited by Papa-Bear-NYC
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I agree with JWAHL. Not only is it difficult to see long lines during the day but you have to worry about vertical refraction and even horizontal refraction, both of which can make your results poor. Second-and third-order observations were usually done during daylight hours, but first-order observations were usually done during darkness. For more information on horizontal refraction see: http://docs.lib.noaa.gov/rescue/cgs_specpu...o247rev1959.pdf , page 135-137.

 

For first-order observations at a USC&GS/NGS triangulation station, the observer and recorder would arrive at the site while it was still light. They would check the previously drafted station description, tape the distances to the reference marks (in both feet and meters), and for a period starting in the 1970s, electronically measure the distance to the azimuth mark. They would usually set up a tripod with light, and possibly mirror, over the azimuth mark. For a reference mark target, at least one observer put a small piece of white, adhesive tape right on the disk next to the center of the arrow and then made a short ink mark on the tape directly above the arrow’s cross bar (the center of the disk). This was for the cases where the reference mark disk could be seen from the top of the Bilby Tower.

 

They then hauled their equipment up the Tower using an electric winch mounted in the back of the observer’s truck. They would then check the plumb of the light plate atop the outer tower using an instrument called a collimator and then install and center the theodolite plate atop the inner tower. The observer then set up the theodolite and began locating the stations to be observed, sometimes placing tape on the platform’s rail marking the direction to the distant stations. If light(s) were to be shown to other observers, the recorder would climb to the top of the outer tower to install and point the necessary light(s). See the following link for a photo from c1934 showing the observer’s tent being installed (to protect the instrument from the sun and wind), and the light-keeper atop the outer tower pointing four lights to four distance observers: http://usasearch.gov/search?v%3aproject=fi...amp;rpaid=& . This photograph shows three people because two were required to read both sides of the older theodolite, and the third person was the recorder. After the Wild T-3 theodolite (see: http://docs.lib.noaa.gov/rescue/cgs_specpu...o247rev1959.pdf , page 29) came into usage, only one observer and the recorder were required. The signal lights and the theodolite lights (for reading the directions) were powered from the battery in the observer’s truck. This was done by using the two towers to conduct the electricity from a battery connection at ground level, through the towers, and then to the bulbs at the top.

 

While it was still light, the observer would then observe directions to the azimuth mark, the reference marks, and any intersection stations (towers, tanks, spires, etc.). When these were complete, and as it began to darken the observer would locate the scheduled signal lights around the horizon, one by one, and call each light-keeper, in turn, and have the light-keeper adjust the light in direction (both horizontal and vertical), and intensity. Once all lights were adjusted, the observer would point and read vertical angles and then horizontal angles to all the scheduled stations. Vertical angles were used to compute the approximate elevations of triangulation stations. The horizontal observations consisted of 16 positions of the theodolite’s horizontal circle. Since each “position” involved a direct and reverse pointing of the theodolite (to help balance out instrument errors), each signal light was actually pointed on 32 times! The recorder hand recorded the observations and kept running means. When the observations were completed, the recorder was expected to immediately tell the observer which lines, if any, needed to be re-observed to meet the accuracy requirements (outside a 4-seconds of arc tolerance from the mean). Once complete, the observer would call each light-keeper and give them the completion signal “DG”. In the early days, the lights were flashed using Morse Code to transmit information between the stations, later radios were used.

 

For stations where only light(s) were to be shown (there were no observations at that station that evening), only one person would go. That person would stay on top of the tower until the light was correctly pointed and then could come down and wait on the ground for the DG signal (assuming the radio communications would work at ground level). I sometimes read the newspaper while sitting at the top of the tower waiting for the observer to check my light.

 

Here are some links for those that would like more information about light-keeping:

 

“Light-Keeper’s Manual” – USC&GS Special Pub. #65, 1936, at: http://docs.lib.noaa.gov/rescue/cgs_specpu...653rded1936.pdf . This shows everything including how to wire the batteries in various combinations, including series-parallel; Morse Code and signals such as “DG”; sample sketch; importance of work; etc.

 

“Manual of Geodetic Triangulation” – USC&GS SP #147, 1959, at: http://docs.lib.noaa.gov/rescue/cgs_specpu...o247rev1959.pdf , pages 45-51, 101-103, and 137-140, all on light-keeping.

 

GeorgeL

NGS

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Fascinating stuff George!

A couple years ago we were visiting some acquaintances of ours in the foothills above us here in the Antelope Valley. After dinner and a few drinks, they started telling us that a few nights previous, they saw lights off in the near distance. They said that the lights were some secret covert Gov't ops and that their Headquarters was the building higher up on the hill (ok- maybe they were putting us on, but they never copped to it and they kept straight faces the entire time). Understand this- The Antelope Valley has been thought by some to be another Pensacola Fla. or Roswell NM type place. Anyway, I'm thinking now, what they might really have been observing, was a night op, first order Benchmark Survey.

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A marvelous account, George!

 

Question: what was the physical diameter of the reflector of one of the lights, and what was its observed circumference when observed at a distance (like 10 mi.). I would think that this would be a key variable (or source of error) in the measurements. [OK, your manual cite answered the first question: 7 inches! Obviously a case of RTFM for me.]

 

P.S. Glad I didn't have the job of climbing up and down a Bilby Tower in pitch darkness!

 

-Paul

Edited by pgrig
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George,

 

Thank you. As usual, you have provided excellent educational information. I always look forward to your posts.

 

I can't seem to get the link below to work. If I knew what search terms you originally used I might be able to find it. Can you help?

See the following link for a photo from c1934 showing the observer’s tent being installed (to protect the instrument from the sun and wind), and the light-keeper atop the outer tower pointing four lights to four distance observers: http://usasearch.gov/search?v%3aproject=fi...amp;rpaid=& . This photograph shows three people because two were required to read both sides of the older theodolite, and the third person was the recorder.

 

Thanks again,

 

--The TillaMurphs

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Wow! I now read in the manual (p.6) that if a Lightkeeper had problems with his smaller dry cells, he was advised to use the storage battery of his truck, wiring one side to the inner tower structure and the other to the outer tower frame, and making contact at the light on top.

 

So not only does the Lightkeeper have to clamber up and down the tower in pitch darkness, he has to do it on an electrified tower! Perhaps in a light rain!

 

I do see now why I have a mystical affinity with these poor people--my facility with code! It does look, however, like the abbreviations would confuse a "normal" operator--like sending "R" for "I missed your msg, pls send again," when over the air, this means the exact opposite!

 

This manual is a great read!

 

-Paul

N1HEL

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Manual, p.21:

 

"Do not leave odd bits of lumber, papers, worn-out cells, or tin cans around the station."

 

Oops! There goes another government guideline...!

 

It's also notable to see that more members of observing parties were fired for truck driving

offenses than for any other reason (careening up those well-cleared trails to the stations!), and that

the government warned staff that their potential for advancement would be directly related to their observed level driving skills!

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OK George, Bill, et al. --after reading the manuals, it strikes me that a team of you Triangulation Greybeards need to plan and schedule an annual "Triangulation Day" (akin to Amateur Radio's "Field Day"), during which Geocaching.com volunteers (and other hangers-on) organize themselves in to "field parties" and carry out a triangulation survey on a set of existing stations. This should be easier in 2009 than it was in 1939! Please keep the towers at 20 ft. or less :ph34r: and do not pick locations involving the rental of pack horses.

 

Let me know when you have this organized and tell me what role you want me to play...

 

Thanks,

-Paul

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While my beard does have a touch of gray, it didn't get that way from surveying experience. I'm just an interested amateur.

 

Actually, I have done a hobby project vaguely like this around where I live. I started with a slightly damaged brass transit and then got a GTS-2B (25 year old 6" station with manual readout of angle and distance).

 

It is more of a resection network than a triangulation network because most of my occupied points are not intervisible from ground level and I certainly am not going to put up towers.

 

I have some supposedly known points, converted to State Plane Coordinates. Only 2 have NGS data sheets (3rd order intersection stations). I have data from the county for a couple more and one that belongs to the company I used to work for. Most are within an area of about 2x5 miles.

 

From several occupied positions I took angles between all visible radio towers (top of red light if any, highest mast if not), the 2 intersection stations when visible, etc. I processed it all in a least squares program and believe I know the position of a point in my driveway within a few tenths of a foot. I can hold some of the known station values and predict another one within about that tolerance. I would expect the county marks done in 1995 or later to be good to a cm or so. I'm in the range where the precise version of NAD83 makes a difference.

 

Since the 3rd order stations are mostly 4-8 miles from the nearest NGS triangulation stations, 1:10,000 would put them within a very few feet at high confidence and possibly better than a foot, and they match my network about so.

 

One mystery remains in that I used two points that had SPC values to 0.001 ft written on laths when they widened a major street, and they don't fit my network solution by around a foot. I had hoped they were GPS-derived and good to cm. I haven't been able to figure out if I have bad measurements or if they were using some kind of rescaled local coordinates on that project (i.e. divide SPC coordinates by scale factor to get distances on surface and offset to hold one point's project coordinates equal to true SPC ? ).

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TillaMurphs and All, Sorry, I didn’t notice that this search used “usasearch.gov”. That search engine only saves its searches for a short time. To find this photo, go to the NOAA Photo Library at: http://www.photolib.noaa.gov/search.html, and click on “Search”. Then enter “survey light” in the search box. A series of photos will come up and it’s the 9th photo. Note, you can also search on other terms like “Bilby Tower” to get some great photos. If you want to see all the photos that I have submitted, search “George Leigh” (10 pages of photos).

 

Pgrig, The size of the light reflector got smaller over the years. The first electric lights used were early, large automobile headlights. Here at NGS we have two signal lights on display that are about 8” in diameter. The reflector diameter on the final light we used (called the “PeeWee” light) was 2 ¾”. For an article on survey signals (including photos of many different light styles) see: http://celebrating200years.noaa.gov/magazi...ls/welcome.html . One of these photos shows the photo that TillaMurphs asked about, see above. The last photo shows the orange PeeWee light, the last variation of signal light. We used these, then new, lights on my survey party about 1980.

 

Regarding the reflector size introducing an error, this was minimized by careful pointing and dimming of the light. As the observer was watching through his theodolite, the light-keeper rotated the light back and forth in the horizontal plane until the observer got the maximum light. They then repeated this in the vertical plane. This procedure should result in the light pointing directly at the observer. Then the observer had the light-keeper dim the light until only a point of light could be seen. You are correct that this was very important. If the light was not properly aimed the light could bounce off one side of the reflector and the observer could end up observing part way out the reflector instead of in the center. This could have introduced an error of several inches when using the older, very large reflectors.

 

Re the electrified tower, that’s what I was attempting to explain in my earlier post – that’s what the observer did all the time, clip truck battery leads onto the tower at the bottom and then use the power at the top. And, I just remembered, the light-keepers did it that way also.

 

P.S. I once climbed up a Bilby Tower knocking ice off each step as I went.

 

Re a “Triangulation Day”, a first step might be to just establish 3 temporary points on the ground that “see” each other, and are not too close together. Then with 3 tripods, 2 signals and a transit, or preferably a theodolite, observe the 3 angles (many times), average the results at each station and then see how close they add up 180 degrees. (The required average triangle closure for Third-Order, Class I was 3 arc-seconds, for First-Order 0.8”.) The observer would, of course, have to write a station description, etc. Especially at short distances, all survey equipment would have to be very carefully centered and angles very carefully measured to have any hope of meeting the above stated closures. It would be hard to find three inter-visible existing stations in the East, but maybe out West. Another possibility would be to start on two known points (need position and azimuth) and then observe a traverse through a few new points and then end up on two known points again. This would require measuring the distances with a tape or electronic distance measuring instrument. For a diagram of a traverse, see: http://celebrating200years.noaa.gov/founda...l/traverse.html .

 

Bill93 – Your project sounds neat. Any time you are using points from different sources you have to expect that they may not be fully compatible.

 

GeorgeL

NGS

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We had a bunch of those PeeWee lights at the DOT. Supposedly donated by NGS back in the mid 1970's after a co-op project in Southern Michigan. NGS also forget to take a couple of those orange NGS umbrella's when the skipped town. We used them a lot on densification projects along US Hwy 2 from St Ignace to Spalding. DOT employees volunteered as light keepers. One of the guys was a LS in the UP always talked about those crazy NGS guys.

Edited by Z15
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