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NGS Surveyor

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  1. Geoides, Glad you liked the contest and seeing the many varieties of USC&GS disks. In my paper there are over 52 different disks described, most with a photo. Hopefully the paper will be on-line very soon. Regarding contests, my next two subjects may be: USC&GS witness posts (wood posts, arrows in stone, metal signs, plastic signs, etc), and old pre-disk USC&GS marks (many varieties, such as chiseled squares, chiseled +, bottles, pots, etc.) GeorgeL NGS
  2. I have written down some detailed instructions on how to write the "To Reach" portion of a station description (or recovery note), see: http://celebrating200years.noaa.gov/magazi...come.html#intro GeorgeL NGS
  3. Difficult Run and All, I meant to mention this in my "awards" post but I forgot. Last year, because of his excellent work in recovering and documenting his early survey mark finds in New England (especially the along the Eastern Oblique Arc), we awarded PapaBear one of the 200th Anniversary commemorative disks! This was long before the contest even started. So, again, Thanks PapaBear for all your good work!! GeorgeL NGS
  4. WINNERS – CONTEST FOR PHOTOS OF USC&GS, NOS, AND NGS SURVEY DISKS A large Thank You to all who submitted photographs and/or information on old survey disks. I have carefully gone through all the submittals and considered all the photographs that met the criteria of being USC&GS and NOAA agency disks and within the correct time period. Many of the photographs were excellent, but fell within the range of know dates, so did not qualify. The winners are listed below. Top prize is a commemorative brass survey mark, honoring the 200th Anniversary of the U.S. Coast & Geodetic Survey (1807 – 2007), see: http://www.flickr.com/photos/12262796@N06/3775260687/ . All other prizes are lapel pins honoring the same event, see:. http://www.flickr.com/photos/12262796@N06/3311544961/ . TOP PRIZE – Geoides for a photo of a flat, stamped plate, PID = HT0688. This is, perhaps, the “missing link” between earlier marks with letters and numbers chiseled in rock, and later survey disks with stamped letters and numbers. Difficult Run – for a photo of a hexagonally shaped, Gravity Station Reference Mark, year c1961, PID = AH7245. These are extremely rare, our gravity field surveyor says that he has only ever seen 4 of these. VagabondWV – for the photo of an old “cup” shaped disk, possibly set as a magnetic station in WV as late as 1944, PID = HX3058. Mega Scooter – for the earliest photo seen of a Magnetic Station, 1917, PID = QE0491, Astro D-Team – for the photo of a Triangulation Station disk with a very large triangle, 1921, PID = PN0027. Harry Dolphin (two) – for the photo of a Triangulation Station flat disk set in 1909, PID = QF0712. And for the photo of a 3” diameter (small) USC&GS AND STATE disk set in 1956, PID = KV0491 . Dixie Dawn – for the photo of a round, Gravity Station disk set in 1937, no PID. Shorbird – for the photo of the first disk I have seen stamped USC&GS and a city – in this case Akron, Ohio, year 1963, PID = MB1249. Thanks again. All winners please email me your snail-mail addresses so I can mail the prizes. GeorgeL NGS
  5. When a mark is not found, its helpful to state the number of person hours spent looking. That gives the next person some idea of how much effort was spent in trying to find the mark. GeorgeL NGS
  6. Airway beacons would also have been on the aeronautical charts - also made by the USC&GS. GeorgeL NGS
  7. Here is a response that was just sent to me by our NGS Wyoming Geodetic Coordinator. GeorgeL NGS "I installed this stainless steel rod in 2004 as a replacement for M158, which had been destroyed by road work. The new mark was observed as part of a re-leveling survey along Park roads between Madison-Norris-Canyon in September 2004. We designed this type of mark for use in wilderness areas such as Three Sisters, where we were asked by USFS to keep our footprint to a bare minimum. The design will accommodate both leveling and GPS observations (note center punch). This type of mark was used only to replace a few destroyed marks in Yellowstone. We expect to have a searchable database of all known (by me) leveling marks in the Park on-line by the end of this year. I can provide a preliminary version on CD-ROM if that would be useful. [Dz]" ________________________________________ Dr. Daniel Dzurisin U.S. Geological Survey
  8. Mike, Here is some information about early leveling reports. The 1907 report is currently being scanned, so it is not on-line yet. 1900 - C&GS Report of the Superintendent 1898-1899, Appendix 8, pgs 347-886, "Precise Leveling in the United States" – http://docs.lib.noaa.gov/rescue/cgs/003_pdf/CSC-0102.PDF 1903 - C&GS Report of the Superintendent 1902-1903, Appendix 3, pgs 189-809, "Precise Leveling in the United States, /1900-1903, with a Readjustment of the Level Net and Resulting Elevations" - http://docs.lib.noaa.gov/rescue/cgs/004_pdf/CSC-0107.PDF 1907 - C&GS published in 1909, "Precise leveling in the United States 1903-1907, With A Readjustment of the Level Net and Resulting Elevations" (to be scanned) 1912 - C&GS Special Publication 18, "Fourth General Adjustment of the Precise level Net in the United States and the Resulting Standard Elevations" - http://docs.lib.noaa.gov/rescue/cgs_specpu...U35no181914.pdf You could also check the USC&GS Annual Reports for the years that interest you, see: http://docs.lib.noaa.gov/rescue/cgs/data_r...al_reports.html The flat top bench mark disks were used from c1903 to c1916, although at least one was used as late as 1932. Here is a section from my survey mark paper on early bench marks (meaning vertical control points only): “Known symbols in the disk center, in approx. chronological order, include: A. Slash (about ¾ inch long) (c1903 – c1913) One was also found from 1932, PID = HT0568, see Figure 19. B. Circle (about 15/16 inch in diameter) (c1907 – c1911); a convex disk with a circle in the center was found dated 1941, PID = AG1367. (Center square mentioned in 1909 and 1914, but not seen), C. Circle with slash inside (c1916 – c1970), this disk is convex, first used for all bench marks, then after c1924 used for tidal bench marks only. D. Three slashes, each with a cross slash about 3/16 inch long; convex disk; most common; text “BENCH MARK” upside down compared to other disks except the TRAVERSE STATION disks. See Figure 31, photo Dan Winester, NGS ; (c1923 – c1985), PID = RL1697. E. One slash, with a cross slash about 3/16 inch long (c1957 – c1970), see Figure 32.” GeorgeL NGS
  9. 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
  10. topflitejr1, There have been times when some folks thought our night operations were "extra-terrestrial" but we stopped doing evening first-order triangulation about 1984, so the lights your friends saw a couple of years ago weren't ours. GeorgeL NGS
  11. PapaBear, Out west the observed lines were even longer. The line from MT SHASTA to MOUNT HELENA was 190 miles - the longest ever observed, even longer than any lines observed in Europe, see Holoscenes excellent map at: http://www.holoscenes.com/cgi-bin/moin.cgi/ShastaTriangle . GeorgeL NGS
  12. 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
  13. From “Manual of Geodetic Leveling, USC&GS, 1948, (http://docs.lib.noaa.gov/rescue/cgs_specpubs/QB275U35no2391948.pdf) From page 43: “Buildings-In general, public buildings, buildings of a memorial character and churches have a longer life than do commercial buildings. On the other hand a new and modern bank building in a city or large town is apt to remain undisturbed longer than an antiquated city hall or county courthouse, unless the old structure has a historical significance which may insure its remaining untouched for that reason. Railroad stations in growing communities are frequently demolished or rebuilt to provide added station facilities for increasing traffic. A bench mark set in the wall of a building is less apt to be disturbed than one set in a step or portico, since these portions of the structure are more frequently changed than the building itself. Bench marks should not be placed on steps or other projecting portions of buildings unless these portions are supported on massive foundations to prevent settlement or heaving from frost action. Bench marks are frequently destroyed or rendered inaccessible by reason of additions being made to the buildings on which they are set. For this reason placing bench marks on the sides of buildings where additions are possible should be avoided.” From page 49: “In stating the character of a mark, such as our standard bench-mark tablet or other similar mark, the mark should be referred to as a “disk”, since that is all that is visible to the person trying to recover it. If the mark is set with the disk in a horizontal position so that the rod can be stood on it, it is not necessary to state that the disk is horizontal. However, if the mark is set in the wall of a building or is placed in a vertical position in any type of structure, so that a rod cannot be stood on it when leveling to or from the mark, this fact should be stated in the description.” From page 65: “Quite frequently the first backsight or the last foresight of a section is made on a tape. This is the case when the bench mark is in the wall of a building and it is impossible to hold a rod on it. The record should indicate clearly what readings were made on a tape and should also include the number of the tape.” For a modern look at the problem see the photo at: http://www.flickr.com/photos/12262796@N06/3707001715/ , which shows a commercially available invar strip (with bar-code) being held on a knife blade centered on the mark on the VERTICAL CONTROL MARK disk. GeorgeL NGS
  14. Papa-Bear, Thanks for the links to the photos of the 1910 BM. I have a photo of this type of disk from 1903 already, so I'm set. GeorgeL NGS
  15. Geoides, Thanks for permission, the paper will be published on-line in the not-to-distant future. The “History Page” is being worked on right now. I will post a note on GC when the paper is on-line. The resolution of your posted photo is fine. Regarding the size of the square mark, I did some calculations and if the letters are 3/16” (the later USC&GS standard), then the size of the square comes out to just about 2” which is what one of the earlier recoverers stated. Papa-Bear, I showed a photo of this square mark to DaveD and he had never seen one like this before either. He said that it could have had horizontal coordinates which were not brought forward from the old Datum (probably due to missing observations or data quality, etc.). I don’t know why USC&GS ended up with some many different kinds of disks. My guess is that USC&GS officials wanted users to be able to easily distinguish between Triangulation Stations and Bench Marks (vertical control). Then, when the decision was made to require Reference Mark disks, they wanted to make sure that the RMs were not confused with the main Triangulation Station disk, so they were made differently. By 1921, there were five types of disks, Triangulation Station, Bench Mark, Magnetic Station, Reference Mark, and Hydrographic Station. The Traverse Station was added in 1924. By 1940, there were 11 types and by 1961 12 styles, some of which had changed. Recently NGS made the decision to have one type of disk. All, Remember July 15th midnight ET is the end of this photograph contest. Thanks, GeorgeL NGS
  16. Geoides, Very interesting that this is a metal plate set in concrete. It might even be the “missing link” between marks with a few letters carved in stone (eg “U S C S”) and the standard round disks which USC&GS starting using about the year 1900. Do you know what the measurements of the plate are? According to the datasheet, this survey mark has an accurate elevation (first-order) but not an accurate horizontal position. Regarding the point of the triangle, I can’t recall ever hearing that the triangle corners pointed to other stations. Sometimes lines were carved in rock radiating out away from the station and pointing to other marks, and sometimes nails were laid in the top of still wet concrete monuments also pointing to nearby stations. Regarding the center-punch mark inside the triangle, perhaps it was intended to later use this point as a triangulation station but it never happened. Regarding old stations in CA, the Coast Survey began surveying on the West Coast in about 1851. George Davidson was in charge of this for many years, see: http://www.history.noaa.gov/giants/davidson.html , and http://www.lib.noaa.gov/researchtools/subj...s.html#DAVIDSON . The Transcontinental Arc of Triangulation work in CA was done in the 1870s and 1880s, see Holoscenes excellent web site at: http://www.holoscenes.com/cgi-bin/moin.cgi/WesternSeries . Regarding research, the USC&GS Annual Reports are on-line at: http://docs.lib.noaa.gov/rescue/cgs/data_r...al_reports.html . Check out the reports around 1892. May I use your photo in my survey marks paper? Thanks, GeorgeL NGS
  17. Geoides, Your photo of station MENDELL is very interesting and indeed unusual. I can't tell from the photo or the description what the mark actually is. Is the lettering carved in stone or concrete, or is the lettering on a metal plate of some type? Thanks, GeorgeL NGS
  18. Anyone know what happened to Buckner Creel's web site listing MANY different types of survey marks? GeorgeL NGS
  19. Does anyone have any photos of a USC&GS flat bench mark disk from 1903 or earlier? I have one of Z 3 1903 (HT0568) but it is a little blurry and I would like a sharp image. This disk had the following stamped around the outer edge “U.S. COAST & GEODETIC SURVEY B.M.” and a single slash in the center. Thanks. This contest for photos of old and unusual USC&GS survey disks will end on July 15th, so hurry and get some more photos in! Thanks, GeorgeL NGS
  20. Stations OLGA and MT OLGA LOOKOUT TOWER If the tower was rebuilt, then the original position given for the tower was lost. This is because it is very unlikely that the second tower was built in exactly the same position. This example illustrates why surveyors must be very careful when using Intersection Stations (towers) as starting azimuths – often times the towers have been rebuilt in slightly different positions. Note that station OLGA (a survey disk) is underneath the tower and the tower was positioned from station OLGA. In the description for MT OLGA LOOKOUT TOWER it states, “The traverse connect was made to the center of the base of the lookout tower.” Then goes on to state that the distance was 1.216 meters. The center of the base of the tower would have been found by stretching strings from the base of opposite legs of the tower and considering the point where the strings crossed to be the center of the tower. The distance was then measured from station OLGA to the string crossing point. GeorgeL NGS
  21. There are also CORS there, see the eastern portion of the map at: http://www.ngs.noaa.gov/CORS/ GeorgeL NGS
  22. Jasper Bilby invented the Bilby Tower in 1926, see: http://celebrating200years.noaa.gov/survey_towers/bilby.html . It was first used in 1927. For a photo of him in about 1903, see: http://usasearch.gov/search?v%3aproject=fi...amp;rpaid=& and another photo of him this time atop of pole doing reconnaissance, see: http://usasearch.gov/search?v%3aproject=fi...amp;rpaid=& GeorgeL NGS
  23. For the official NGS statement on the Four Corners Monument, see: http://www.ngs.noaa.gov/INFO/fourcorners.shtml GeorgeL NGS
  24. Several of us here at NGS watch the on-line auction site and if we see a USC&GS or NGS disk listed we send an email to the seller explaining the significance of the disk and ask them politely to remove it. If they don't, then we send an email to the auction site asking them to remove the item. GeorgeL NGS
  25. Mega Scooter, Thanks for the excellent photos of a very green “old-style” cup disk. Your side view really shows how deep the center area is recessed. We have one of this type (with the triangle on the central, recessed area) mounted on a display here in NGS, but I have never seen one in the field. GeorgeL NGS
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