NGS Surveyor

Patty, I was able to click on your links and see the eBay listing for each. However, I would rather have seen the message you quoted blocking them. Several of us here at NGS have been trying to ban the sale of our survey disks for several years (by sending emails to the seller and, when necessary, eBay). Any sales of survey disks could encourage some folks to go out and start prying disks out of the ground - we certainly don't want that! GeorgeL NGS

All the T-shirt orders I have received are being mailed today. I still have a very few XXL T-shirts. GeorgeL NGS

Shorbird - great story! Bill93 - No immediate plans for another contest. Rather busy right now. I only have long-sleeved, size XXL T-shirts left. GeorgeL NGS

I have a few USC&GS T-shirts left ( I originally mentioned these several months ago). See photos at: http://www.flickr.com/photos/12262796@N06/4644665095/ http://www.flickr.com/photos/12262796@N06/4130853597/ http://www.flickr.com/photos/12262796@N06/4131615738/ The Bench Mark on the front is a very close copy of an actual USC&GS Bench Mark. The design on the back is the famous USC&GS Eagle, standing on the globe and surveying using a sextant. The old USC&GS flag waves in the background. These are being sold by the USC&GS Heritage Society. We only have size XXL left. Long sleeve are $16 and short sleeve are $14. Packaging and postage are about $6. Let me know if you are interested, George.Leigh@noaa.gov

I was just looking at the several metal Witness Post signs on my desk and noticed that one of the USC&GS signs has a 2-digit zip code and one has a 5-digit zip code. So, the 2-digit is pre-1963, and the 5-digit is between 1963 and 1970 (when NOAA was formed). GeorgeL NGS

There are at least 4 versions of metal U.S. Coast & Geodetic Survey signs, and I only know of one version of NGS metal Witness Post signs. See my site on FLICKR at: http://www.flickr.com/photos/12262796@N06/4565722774/ for photos of the 5 signs. The USC&GS sign with the name STUDDS is from the period May 1950 to August 1955 when RADM Studds was the Director of the USC&GS. The sign with the 2-digit zip code is prior to Julyl 1963 when 5-digit codes came into usage. I have not seen any text references with dates for various Witness Posts. GeorgeL NGS

Hi, They are called the USCG Light Lists - see: http://www.navcen.uscg.gov/pubs/LightLists/Lightlists.htm GeorgeL NGS

Underground marks were specified by the USC&GS as early as 1905. By 1959 the specifications were published in USC&GS Special Pub. #247, “Manual of Geodetic Triangulation” (http://docs.lib.noaa.gov/rescue/cgs_specpubs/QB275U35no247rev1959.pdf) From page 14 of SP#247: “14. Marks.-Detailed specifications for marking stations are given on pages 84 to 95. Each station will be permanently marked. Surface and underground marks are to be used where local conditions permit.” From page 88: “5. Station mark.-Each station center should be marked with a standard triangulation mark of the type illustrated in figure 48. The mark should be set in the manner described in section 10. An underground station mark should also be set under the surface mark wherever conditions permit. Marks of other organizations may be used as described in section 9. The upper station mark may also be set underground when necessary, as when the station is in a cultivated field.” See also Section 10 on page 90, diagram on page 92, photo on page 93, Section 10(d) on page 93, and “notes” for Underground Marks on page 121. GeorgeL NGS

Remember, the stamping on a disk and the official designation (name) are often not the same. Typically, the year stamped on a disk is not part of the station's designation. GeorgeL NGS

Paper copies of recovery notes are a requirement for our contractors only. GeorgeL NGS

I recently updated our specifications for contractors writing station descriptions and recovery notes, see below. These are not on-line yet, but will hopefully be in about a month. GeorgeL NGS -------- ATTACHMENT S: WRITING STATION DESCRIPTIONS AND RECOVERY NOTES Descriptions are one of the end products of surveying, along with the positions and the survey marks themselves. All three shall be of highest quality. The descriptions must be complete, accurate and in standardized format if the station is to be reliably and easily recovered for use in the future. Descriptions shall be in the standard National Geodetic Survey (NGS) format of three paragraphs as described in Section 2 “Description Format”. 1. GENERAL 1.1 DEFINITION OF DESCRIPTION VS. RECOVERY NOTE A. A description details the location of a new survey mark, or one not previously in the NGS digital database. B. A recovery note is an update and/or refinement to a description already in the NGS digital database, written upon a return visit to a survey mark. 1.2 LEVELS OF COMPLEXITY OF RECOVERY NOTES A. No Changes - If an existing station's digital description is complete, accurate, and meets Blue-Book requirements, the station may be recovered with a brief recovery note, such as “RECOVERED AS DESCRIBED”. B. Minor Changes - If minor changes or additions to the description are required, they may be added after the above phrase, such as “RECOVERED AS DESCRIBED, EXCEPT A NEW WOODEN FENCE IS NOW 3 METERS NORTH OF THE STATION”. See typical cases listed in Section 1.5 A. C. Major Changes - Where major changes have occurred, major inaccuracies are found, or where required information is missing (in any portion of the description), a complete three-paragraph recovery note, with the same format as a new description, is required. If a measurement discrepancy is found, state that the new distance was verified, for example, by taping in both English units and metric units or by two separate measurements by two different people. See typical cases in Section 1.5 B. D. Exemption - If a recovery note has been written for the station within one year and no changes have taken place, a new recovery note is not required. Note, this may cause an error message in the description checking software, which may be ignored. 1.3 SOFTWARE - Descriptions and Recovery notes must be properly encoded into a D-file by using software WinDesc. For WinDesc information see: http://www.ngs.noaa.gov/PC_PROD/pc_prod.shtml#WinDesc , use the latest version available. Also refer to the NGS Web site: http://www.ngs.noaa.gov/FGCS/BlueBook/, Annex P (Geodetic Control Descriptive Data), for information. Note: WinDesc may be used for both new Descriptions and for Recovery Notes. For projects that have no new marks and are not being “Blue-Booked”, the NGS on-line recovery method may be used to submit Recovery Notes; see: http://www.ngs.noaa.gov/ngs-cgi-bin/recvy_entry_www.prl . Submit paper copies for any recovery notes submitted on-line. 1.4 CHECKING - Descriptions shall be written by one person and checked by another. Recovery notes shall also be checked. For example, a mark setter can draft a description immediately after setting the mark, and an observer can check the description during observations. For existing marks, the reconnaissance person can draft the recovery note and the observer can check it. Descriptions and Recovery Notes should be written while at the station or immediately after visiting a station so that all details are fresh in the writer's mind. 1.5 TYPICAL RECOVERY NOTE CASES A. A brief, one or two sentence Recovery Note is adequate: i. When the mark is found and the description is completely accurate, sample: (“RECOVERED AS DESCRIBED”), ii. When the mark is found and there are one or two minor changes, (“RECOVERED AS DESCRIBED EXCEPT A NEW WOODEN FENCE IS NOW 3 METERS NORTH OF THE STATION”), iii. When the mark is not found, (“MARK NOT FOUND AFTER 3 PERSON-HOUR SEARCH”), iv. When the mark is not found and presumed destroyed, (“MARK NOT FOUND AND PRESUMED DESTROYED. CONSTRUCTION FOREMAN STATES THAT THE MARK WAS DESTROYED YESTERDAY”), v. When the mark is found destroyed, (“THE MARK IS DESTROYED AND THE DISK HAS BEEN SENT TO NGS” or “THE MARK IS DESTROYED AND ITS PHOTOGRAPH HAS BEEN SENT TO NGS”). Note, for a station to be considered destroyed by NGS, the disk or photograph showing the destroyed mark must be received by NGS. Otherwise, report the station as “NOT FOUND”. B. A complete, new, three-paragraph Description/Recovery Note is required: i. When a new, permanent mark is set, ii. When an existing mark does not have a Permanent Identifier (PID), iii. When an existing mark does not have an National Spatial Reference System (NSRS) digital description (i.e., description is not in the NGS database), iv. When an existing mark has only a brief description not meeting the three-paragraph requirement (many bench marks have only short, one-paragraph descriptions), v. When an existing mark's description is no longer accurate or complete. 2. DESCRIPTION FORMAT The original U.S. Coast & Geodetic Survey (USC&GS) Special Publication No. 247, MANUAL OF GEODETIC TRIANGULATION, page 116, states, “A description must be clear, concise, and complete. It should enable one to go with certainty to the immediate vicinity of the mark, and by the measured distances to reference points and the description of the character of the mark, it should inform the searcher of the exact location of the mark and make its identification certain. It should include only essential details of a permanent character.” NGS still follows these guidelines, so that a person with a minimal background in surveying and no local geographic or historical knowledge can easily find the mark by logically following the text of the description. 2.1 FIRST PARAGRAPH - The first paragraph is the description of locality. This part of the description begins by referring to the airline distance and direction (cardinal or inter-cardinal point of the compass) from the three nearest well-known mapped geographic feature(s), usually the nearest cities or towns. Use three references equally spaced around the horizon, if possible. In writing the Description, always progress from the farthest to the nearest reference point. Distances in this part of the description shall be in kilometers (followed by miles), or meters (followed by feet), all distances to one decimal place. Detailed measurements which appear elsewhere in the description should not be repeated in this paragraph. Points of the compass should be fully spelled out. Do not use bearings or azimuths. State the name, address, and phone number of public sector property owners (however, phone numbers of private property owners are NOT included). State any advance notice and security access requirements for reaching the station. Also state any unusual transportation methods that may be required to reach the station. Sample first paragraph: “STATION IS LOCATED ABOUT 12.9 KM (8.0 MILES) SOUTHWEST OF EASTON, ABOUT 6.4 KM (4.0 MILES) NORTHWEST OF CAMBRIDGE, AND ABOUT 3.6 KM (2.2 MILES) EAST OF SMITHVILLE ON PROPERTY OWNED BY MR. H.P. LAYTON, AND KNOWN AS OLD GOVERNOR JACKSONS ESTATE.” 2.2 SECOND PARAGRAPH - The second paragraph contains the directions to reach the station. This section is one of the most useful parts of a description. It usually enables a stranger to go directly to a station without a delay due to a detailed study of maps or of making local inquiries. It is a route description which should start from a definite point, such as (a) the nearest intersection of named or numbered main highways (ideally Interstate and U.S. highways, or at least those which are shown on commonly used road maps), and approximately where that intersection is, or ( some definite and well-known geographical feature (e.g. main post office or county courthouse) and give its name and general location. Odometer distances shall be given to tenths of kilometers (followed by tenths of miles). For roads with names and numbers, give both in the first occurrence. A. The format for the first leg of the “To Reach” is: i. FROM THE MAIN POST OFFICE IN DOWNTOWN SMITHVILLE, or FROM THE INTERSECTION OF INTERSTATE XX AND STATE HIGHWAY YY, ABOUT 4.8 KM (3 MILES) NORTH OF SMITHVILLE; ii. GO A DIRECTION (north, northeast, northerly, northeasterly, etc.); iii. ON A ROAD (name and number of road or highway); iv. FOR A DISTANCE (km followed by miles in parentheses); v. TO SOMETHING (intersection, or fork in road, or T road left or T-road right). B. The format for additional legs, as needed: i. TURN LEFT OR RIGHT, OR TAKE RIGHT OR LEFT FORK, OR CONTINUE STRAIGHT AHEAD; ii. GO A DIRECTION (north, northeast, northerly, northeasterly, etc.), iii. ON ROAD (name or number of road or highway); iv. FOR A DISTANCE (km followed by miles in parentheses); v. TO SOMETHING (intersection, or fork in road, or side-road left or right, or station on left or right). Repeat Section B as required. All five parts of each leg shall be included in each “To Reach”. Sample: “TO REACH THE STATION FROM THE INTERSECTION OF INTERSTATE 300 AND MAIN STREET (STATE HIGHWAY 101) IN JONESVILLE, GO EASTERLY ON HIGHWAY 101 FOR 3.7 KM (2.3 MILES) TO AN INTERSECTION. TURN RIGHT AND GO SOUTH ON MILLER ROAD FOR 5.1 KM (3.2 MILES) TO A SIDE-ROAD RIGHT. CONTINUE SOUTH ON MILLER ROAD FOR 6.6 KM (4.1 MILES) TO AN INTERSECTION. TURN LEFT AND GO EASTERLY ON SMITH ROAD FOR 2.4 KM (1.5 MILES) TO STATION ON THE LEFT IN THE FENCE LINE.” Use the word “EAST” if the road goes due east and “EASTERLY” if the road wanders in a general easterly direction. Use intermediate references, such as the “side-road right” off Miller Road above, if the distance in a leg becomes longer than about 5 miles. The place at the end of truck travel should be mentioned. If walking is required, note the approximate time required for packing. If travel to the station is by boat, the place of landing should be stated. 2.3 THIRD PARAGRAPH - The third paragraph provides details of the mark and reference measurements. A new, Third Paragraph shall contain the following information, unless the same information has already been entered into a special field in the WinDesc software. (A) The station mark type; ( How the mark is stamped; © How the mark is set; (D) Reference measurements; (E) Hand-held GPS observations; (F) Primary Airport Control Station (PACS)or Secondary Airport Control Station (SACS) designation, if appropriate. Older descriptions will usually be in this format: SECTION EXAMPLE (A) - What the mark is: THE MARK IS AN NGS HORIZONTAL DISK, or A USC&GS TRIANGULATION DISK, or A STAINLESS STEEL ROD, or A CHISELED “X”, ETC.), ( - How the mark is stamped (in dashes): STAMPED --JONES 1952--. © - How and in what the mark is set: THE MARK IS SET IN A DRILL HOLE IN BEDROCK, or SET IN A SQUARE CONCRETE MONUMENT, or IS A ROD DRIVEN TO REFUSAL, ETC. A GREASE-FILLED SLEEVE ONE M LONG WAS INSTALLED. Specify whether the rod was driven to refusal or whether it met the slow driving rate (this is specified in Attachment V, Section 4.0 as 60 seconds per foot or 90 feet). It shall also state the length of rod driven. Also state if a grease-filled sleeve was installed and its length. For a rod mark, the diameter of the stainless steel rod and the diameter of the PVC pipe with the aluminum cap should be in English units, and the length of the plastic sleeve should be given in metric units only. - State if the mark projects above the MARK PROJECTS 15 CM (5 IN), OR ground, is flush, or is recessed and the MARK IS FLUSH WITH THE GROUND, amount, (for a rod mark state the above OR MARK IS RECESSED 20 CM (8 IN); for both the rod and the logo cap): OR LOGO CAP IS FLUSH WITH THE GROUND AND TOP OF ROD IS 10 CM (3.9 IN) BELOW THE TOP OF THE LOGO CAP, - State the depth of the monument, if known CONCRETE MONUMENT, 1.2 M (4FT) DEEP, OR, ROD DRIVEN TO REFUSAL AT 15 M (49 FT) (D) - State reference distances and directions IT IS 20.7 M (67.9 FT) SOUTHWEST OF from three or more permanent objects in the POWER POLE #2345, 15.2 M (49.9 FT) mark's immediate vicinity (farthest to WEST OF THE WEST EDGE OF HIGHWAY 134, AND 3.4 M (11.1 FT) nearest), and equally spaced around the NORTH OF A CHAIN-LINK FENCELINE. horizon: Examples of objects used as references: existing reference marks, witness posts, center lines of roads, edges of roads, edges of runways, ditches, power or telephone poles, and buildings. Start with the farthest distance. Horizontal distances should be used. If slope distances were measured, that fact should be stated in the paragraph. Specify whether the reference distance was from the center or the edge of the reference object, and specify which edge, like “north edge”. The distances shall be in meters (followed by English measurement units in parentheses, except as noted in © above), and the directions shall be cardinal and inter-cardinal directions, fully spelled out, such as “NORTH”, “NORTHEAST”, or “NORTH-NORTHEAST”. Magnetic bearings from the reference objects are recommended to assist in future recoveries. (E) Provide a handheld GPS position for all new and recovered marks, and for all proposed mark locations. Include the position and the accuracy code of HH1 or HH2, depending on the type of receiver used. HH1 stands for Hand-Held accuracy code 1 (differentially corrected, hand-held GPS), and HH2 stands for Hand-Held accuracy code 2 (stand-alone, hand-held GPS), as follows: Accuracy code 1 (HH1) = ± 1-3 meters Accuracy code 2 (HH2) = ± 10 meters GPS Data Formats: CODE LATITUDE LONGITUDE SECOND PLACES HH1 NDDMMSS.ss WDDDMMSS.ss (2 places of seconds) HH2 NDDMMSS.s WDDDMMSS.s (1 place of seconds) Use “N” or “S” for latitude and “W” or “E” for longitude. Use three digits for the degrees of longitude, adding one or two leading zeros if required. (F) If the station is a Primary or Secondary Airport THIS STATION IS DESIGNATED Control Station mark, the third paragraph shall end AS A PRIMARY AIRPORT CONTROL with the appropriate designation of Primary or STATION. Secondary Airport Control Station): Sample for a rod mark: “THE STATION IS THE TOP-CENTER OF A 9/16 INCH STAINLESS STEEL ROD DRIVEN TO REFUSAL AT A DEPTH OF 18M. THE LOGO CAP IS STAMPED --SMITH 2003--. THE LOGO CAP IS MOUNTED ON A 5 IN DIAMETER PVC PIPE. A ONE METER LONG GREASE-FILLED SLEEVE WAS INSTALLED. LOGO CAP IS FLUSH WITH THE GROUND AND TOP OF ROD IS 10 CM (3.9 IN) BELOW THE TOP OF THE LOGO CAP. THE MARK IS 32.4 METERS (101.74 FEET) NORTHEAST OF NORTHEAST CORNER OF THE HOUSE, 16.62 METERS (54.5 FEET) NORTH OF WATER PUMP ALONGSIDE OF HEDGE AROUND OLD FLOWER GARDEN, AND 4 METERS (12.96 FEET) NORTH OF NORTHEAST CORNER OF HIGH HEDGE ENCLOSING OLD FLOWER GARDEN. THE HH1 GPS IS: N304050.2, W1201020.4.” Sample for a concrete monument: “THE STATION IS AN NGS HORIZONTAL CONTROL DISK, STAMPED --JONES 2003-- SET IN A ROUND CONCRETE MONUMENT 1.2 M (4 FT) DEEP AND 0.3 M (12 IN) IN DIAMETER. IT IS SET FLUSH WITH THE GROUND. IT IS 32.4 METERS (101.74 FEET) NORTHEAST OF NORTHEAST CORNER OF THE HOUSE, 16.62 METERS (54.5 FEET) NORTH OF WATER PUMP ALONGSIDE OF HEDGE AROUND OLD FLOWER GARDEN, AND 4 METERS (12.96 FEET) NORTH OF NORTHEAST CORNER OF HIGH HEDGE ENCLOSING OLD FLOWER GARDEN. THE HH1 GPS IS: N304050.2, W1201020.4.” 3. IMPORTANT POINTS REGARDING DESCRIPTIONS 3.1 NAMES - Use the station designation (name) and PID, exactly as listed in the NGS database, in all survey records. Do not add dates, agency acronyms, or other information to the name, nor the stamping. Do not use abbreviations of the name. Note, frequently the stamping and the official station designation are not the same. For example, stampings include the year set, but designations generally do not. 3.2 TERMINOLOGY - Correct NGS survey terminology shall be used in all station descriptions and reports (see GEODETIC GLOSSARY, NGS, 1986). 3.3 DISTANCES - All measurements are assumed to be horizontal unless labeled “slope”. Distances measured from a line (e.g., the center-line of a road or a fence line) are assumed to be measured perpendicular to that line. The origin of measurements at the junction of two roads is assumed to be the intersection of center-lines of both roads. Measurements are assumed to be from the center of an object (i.e. power pole) unless stated otherwise. 3.4 REPAIR - Any work done to repair a mark shall be described completely in the updated recovery note. Note: a repair strengthens the mark but must not change its position, elevation, or orientation. For example, adding concrete or epoxy around a disk where some is missing is a repair. 3.5 REFERENCE MARK NAMES - Note, reference marks are abbreviated “RM x” in descriptions, but on “Reference Mark” disks they are stamped “NO. X”. Also, some reference marks and some azimuth marks have their own PID. 3.6 METRIC CONVERSION - Use the U.S. Survey Foot conversion, in which 3.2808333333 feet equals one meter. 3.7 ABBREVIATIONS – KM = kilometer, M = Meter, CM = centimeter, and NM = nautical mile, MI = mile, FT = feet, IN = inch. 3.8 GPS OBSERVATIONS - Remember to enter "Y" into the satellite usage code field in the Header Record if the mark is suitable for survey-grade GPS observations.

From NGS' GEODETIC GLOSSARY (not on-line): Survey Station - (1) A point at which or from which observations have been made for a geodetic survey. (2) A definite point, on the Earth, whose location has been determined by geodetic surveying. (3) A point, on a traverse, over which an instrument is placed (a setup). (4) On a traverse, a length of 100 feet measured on a given broken, straight, or curved line. (5) A stake indicating one end of a 100-foot-long interval on a traverse. The nature of a survey station is usually indicated by adding a term that describes the station's origin or purpose, for example, triangulation station, topographic station, or magnetic station. A survey station may or may not be marked on the ground. If it is, a geodetic marker (monument) of special construction, or a natural or already present artificial structure is often used to mark the station. GeorgeL NGS

Great photos of marks and scenery!! I especially enjoyed seeing the 1910 flat, triangulation station disks. That type of disk only started being used in c1909. I did an Inertial Survey System (ISS) test in the Yuma area in 1981. The then NGS Arizona State Advisor (LW) and I recovered 99 stations. Check out our 1981 recoveries along U.S. 95 north of Yuma and north to Quarzite and also east along the east-west road just north of I-8 (GEL is me.). Our goal was to set up North-South and East-West test courses for the ISS (since the rotation of the earth was likely to effect the ISS). We then had a helicopter fly the ISS along the test courses and land periodically on top of the known control. The ISS worked well but was soon replaced by GPS. Over the years, LW recovered many of the old marks in AZ and I remember him telling how he found an Indian necklace on a ledge while climbing up to one of the stations. GeorgeL NGS

I recommend including the type of fence(s), e.g. barbed wire, chain-link, split-rail, etc. Also, remember to list the reference distances from longest to shortest. GeorgeL NGS

From the USC&GS “bible of triangulation”, Special Publication No. 247, “MANUAL OF GEODETIC TRIANGULATION, page 89: “8. Witness posts.--In order to aid in the preservation and to serve as a means of easy recovery of the monuments being established, a wooden post will be set adjacent to the concrete station monument or near one of the reference marks at each station, preferably at the station mark. This post shall be 4“x 4” in cross section, about 3 1/2 feet in length, and shall be set to project 15 to 18 inches above the ground surface. The top should have a 1/4 to ½ inch bevel. It shall be painted white and shall have lettered thereon in black the legend “U.S. (triangle)” or U.S. (triangle) R.M.” These posts will be set for monuments established along public highways, in rural districts, along the rights-of-way of railroads, and along the shore lines of rivers and lakes. They need not be set for monuments established along business streets, in residential sections of cities, on the grounds of schools 2nd churches, in cemeteries, in cultivated farm lands, or on bare mountain tops. For survey stations established in cultivated fields and marked with an underground mark, the post shall be set at a reference mark." This publication was updated in 1959. Since then Witness Posts were changed to metal signs on metal posts, and more recently to fiberglass posts with labels. GeorgeL NGS

LSUfan, Here is what the DB guy said: We have a RAYVILLE RESET (CU7543) in the data base , set in 1970, However, there isn't a position or an elevation on the mark ( I need to move the position and obs to the reset mark and scale an elevation in order to get the mark published.) LSU fan can send in a recovery note and a picture if he/she wants to and I'll fix up the mark tomorrow. Thanks for your input, GeorgeL NGS

LSUfan, I sent your info to our "database guy". I'll let you know what he says. GeorgeL NGS

Some thoughts on finding the Cache. 1. Plot 3 or 4 of the points on a map as suggested by 2oldfarts and obtain an approximate position for the unknown point “C”. You mainly just need to know where “C” is with respect to the other points, north or south, east or west. 2. Pick two of the survey marks that have adjusted horizontal positions. Call them points “A” and “B”. Do an “inverse” between them using NGS’ on-line software (need to enter the lat. and long. of each point). The inverse will give you the distance between points “A” and “B” (called AB), and the azimuths each way between “A” and “B”. 3. You now have the three sides of a triangle, AB from the inverse, AC from the list of given distances, and BC also from the list of given distances. 4. Use the Cosine Law to find the angle at point “A” of the triangle. 5. From the inverse done in step #2, find the azimuth from “A” to “B”. 6. From the map (step 1) determine if you need to add the angle at “A” to the azimuth from “A” to “B”, or subtract it (is point “C” to the left or right of the line AB?) The result of this arithmetic will then give you the azimuth to “C”. (Remember, azimuths increase clockwise.) 7. Using NGS’ on-line “forward” software, enter the lat. and long. of “A”, the azimuth to “C”, and the distance AC, and the result will be the lat. and long. of “C”. To check the results, select two different points for “A” and “B”. The result should be very close. Note, “inverse” and “forward” are in the “Geodetic Tool Kit” under “Tools” on the NGS Home Page. GeorgeL NGS

For those interested in Satellite Triangulation, there is a two-part article in the January 2010 and March 2010 issues of "Professional Surveyor" magazine, see below. THE BEGINNINGS OF SATELLITE GEODESY A two-part article on the USC&GS satellite triangulation project of the 1960's is included in the January 2010 and March 2010 issues of "Professional Surveyor" magazine. The articles were written by George Cole, former USC&GS employee and participant in the project. Part 1 is at: http://www.profsurv.com/magazine/article.aspx?i=70528 and part 2 is at: http://www.profsurv.com/magazine/currentedition.aspx , and scroll down to the article. There is also an article on USC&GS/NGS using satellites for surveying on the 200th Anniversary web site at: http://celebrating200years.noaa.gov/founda...come.html#intro , entitled "Entering the Space Age: The Evolution of Satellite Geodesy at the Coast and Geodetic Survey". GeorgeL NGS

A USC&GS publication on leveling, listed on the NGS “History” page as not available digitally, is now available on-line. The title is “Precise Leveling in the United States, 1903 – 1907” see: http://docs.lib.noaa.gov/rescue/cgs_suppl/...391903-1907.pdf . Another publication not listed on the NGS “History” page is available in hard-copy at the NOAA Libraries in Silver Spring, MD and Miami, FL. The title is “Descriptions of bench marks in the United States: with a readjustment of the level net and resulting elevations” 1934. It is not available on-line. GeorgeL NGS

Frex3wv, Re your question, “Can someone tell me the significance of Tidal marks - why so many so close together…” USC&GS/NOAA has two types of bench marks (I’m discussing only vertical control points). The first are “geodetic bench marks,” and the second are “tidal bench marks.” Geodetic bench marks are surveyed with respect to the current national vertical datum which is NAVD 88. These are spaced along lines surveyed by spirit leveling and are normally not close together. Tidal bench marks (BM) are surveyed with respect to their nearby tide gauge. Since ocean water levels vary from place to place, each tide gauge usually has a slightly different “zero.” Three to ten tidal bench marks are set and leveled to at each tide gauge location. These tidal BM are normally set within one mile of the tide gauge. The reason for having multiple tidal BM is to help ensure a permanent record of the datum (zero) established from the tide gauge observations at that location. For the detailed specifications for tidal BM, see: http://tidesandcurrents.noaa.gov/publicati..._Bench_Mark.pdf . For descriptions of the different types of disks, see my paper on USC&GS and NOAA survey disks at: http://www.ngs.noaa.gov/web/about_ngs/hist...ey_Mark_Art.pdf . GeorgeL NGS

A small percentage of tanks and towers were positioned by traverse. This one clearly states that. I recall a case where we turned a direction to the a large standpipe (tank sitting on ground), measured to the near edge of the tank, measured the circumference of the tank, computed the radius of the tank, and add the radius to the distance to the near edge of the tank and obtained the distance to the center of the tank. Thus, the tank had a position determined by traverse. If there is nothing to point on to obtain the direction to the center of the tank, the observe sometimes observed both tangents (left and right edges) of the tank and meaned the directions. Since this is an unusual case, the recovery note should explain the situation. GeorgeL NGS

The RESET was installed because the guard rail (evidently built after the older disk was set), was directly over the older mark so that a level rod could not be held on the disk. The older disk was not in danger, it just wasn't usable. For some reason the older mark must not have been included in the NAVD 88 readjustment, so its NGVD 29 height was converted to NAVD 88 using VERTCON, see notes copied and pasted below. Also note that this datasheet has links to 3 photos of the mark. HT0496* NAD 83(1986)- 37 31 46.50 (N) 122 21 45.39 (W) HD_HELD1 HT0496* NAVD 88 - 93.15 (+/-2cm) 305.6 (feet) VERTCON HT0496 ___________________________________________________________________ HT0496 GEOID HEIGHT- -32.58 (meters) GEOID09 HT0496 VERT ORDER - FIRST CLASS II (See Below) HT0496 HT0496.The horizontal coordinates were established by differentially corrected HT0496.hand held GPS obs and have an estimated accuracy of +/- 3 meters. HT0496 HT0496.The NAVD 88 height was computed by applying the VERTCON shift value to HT0496.the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.) HT0496.The vertical order pertains to the NGVD 29 superseded value. HT0496 HT0496.Photographs are available for this station. GeorgeL NGS

Another clue is that the station is listed as "Third-Order". Intersection stations were "Third-Order. GeorgeL NGS

All, Several of us are trying to learn more about the USC&GS bench marks (vertical control) from c1903 to c1920. Many of these disks are flat, quite thick and have Bench Mark abbreviated as “B.M.”. Later disks have it spelled out as “BENCH MARK”. At least some of the “B.M.” variety have only two rows of factory stamping. The “BENCH MARK” variety seem to have three rows of factory stamping, adding “FOR INFORMATION WRITE TO THE SUPERINTENDENT, WASHINGTON D.C.”. Most have a single “slash” as the center symbol, although a circle appeared in the center about 1907. A circle with a slash inside the circle appeared about 1916 and convex disks appeared c1916. In publications from 1909 and 1914, a square center symbol was mentioned, but I have never seen a photo or drawing of one of these. If you have recovered a USC&GS bench mark from this era, please post a link on this thread, ideally with a photo. Thanks, GeorgeL NGS