Jump to content


+Premium Members
  • Posts

  • Joined

  • Last visited

Everything posted by jwahl

  1. Auxiliary Meander Corner: These are set on small islands when they are surveyed. The BLM Manual of Surveying Instructions 1973 Chapter 3 Section 122 states in part: Any township boundary or section line which will intersect an island is extended as nearly in accordance with the plan of regular surveys as conditions permit, and the usual township, section, quarter-section, and meander corners are established on the island. If an island falls in two sections only, the line between the sections should be established in its proper theoretical position based upon suitable sights and calculations. If an island falls entirely in one section, and is large enough to be subdivided (over 50 acres in area), a suitable sight or calculation is made to locate on the margin of the island an intersection with the theoretical position of any suitable subdivision-of-section line. At the point thus determined a "special meander corner" is established. In the case of an island falling entirely in one section and too small to be subdivided, an "auxiliary meander corner" is established at any suitable point on its margin, which is connected with any regular corner on the mainland. The direct course and length of the connecting line is given in the field notes and shown on the plat. Minnesota GLO plats are online. Here are two which cover islands in that township Plat 1 Another To download higher res versions -jlw Alternate Meandor Corner?
  2. Great research and interesting history.. Your GPS coordinates on some of them you've found would prove interesting. I did some NGS searches around a number of the points on your list and found a few that show up. What I was trying to do is see what shifts or differences there were between NAD83 and the astro positions given. This would help validate that there is no particular reason to suspect the monument has moved based on the coordinate. Here are a few: Beaver, UT 112 38 35.90, 38 16 23.28 W1123836 NAD83 JO0509 38 16 24.72047(N)/112 38 29.33655(W) shifts in seconds 1.44S/6.56W *Gunnison, UT 111 49 15.00, 39 09 25.62 NAD83 KN0411 39 09 30.14434/111 49 15.67291 shift in seconds 4.54S/W0.67 Ogden, UT 111 59 54.64, 41 13 08.56 41 13 11.3/111 59 40.1 shift is 2.74S/14.54W Salt Lake City, UT 111 53 42.90, 40 46 03.76 NAD83 LO1008 111 53 29.54336(W) shift in seconds 6.75S 13.356W and for this monument: Camp Douglas, UT 111 50 14.07, 40 45 47.58 (astronomical monument) GPS given at the top of this thread in DMS 40-45-54.24/111-50-00.12 6.67S/13.95W Is not inconsistent with the rough shifts and variations with other monuments and particularly in that area, i.e. Salt Lake shown right above it. And then the flagpole may also corroborate. Lots of fun.. Thanks - jerry
  3. As I inferred the other day, there is no reason to believe that the monument has been moved, the coordinates are just in another system. BTW the format is common the seconds symbol being used in lieu of the decimal point for decimal seconds. I have seen it many times. So how to convert from NAD83 coordinates to 1880's era astronomic coordinates is a good question. First, the earlier datums specifically NAD27 is inherently closer to astronomic because the model is closer to the actual earth shape for North America. NAD83, is based on a world best fit ellipsoid. Anyway I think that either can be converted back since the gravity components are now readily available. I would have to revisit some NGS publications to get the form to use, and then use the deflec programs. They are available on the NGS website and there is probably an online interactive version also. If I give it a try I can try to outline what I come up with later this weekend. If the station is pure astronomic position, then it will have some inherent error due to the imprecision of the time and instrumentation used. A very interesting and fun find to explore the history of - jerry AFAIK the datum was WGS84; I'm running a Garmin eMap with old firmware (2.04) and it doesn't seem to allow any datum selection. My GPSr reported an accuracy of 16.4 feet. IIRC the "accuracy" measurement is some sort of user-friendly, non-standard Garmin thing, so I'm not sure exactly what it means. I should also mention that I've only taken one reading there, and it sounds like for best results I should take a few and combine them.
  4. It could be a lot of things, but remember that meridians established for survey or boundary purposes in the mid 1800's would have been established by complex and difficult astronomical observations. One thing is that they would not be based on NAD83 datum that your GPS is. Also somewhat difficult to be precise due to uncertainties of time (remember the famous longitude problem), and limitations in instrumentation available at the time being mechanical theodolites that often had to be transported into the frontier and would not be observatory quality. There are many examples of such lines, and they will all be off, particularly E-W from a modern GPS position. It could also be a meridian stone used to set or calibrate or test compass' or other equipment. I think the plack on top is probably un related. - jlw
  5. Is this about where it was? Was it here? (Topozone) - jlw
  6. Neither are "bench marks". They are General Land Office Land Survey monuments for 2 different 1/4 section corners. - jerry wahl
  7. That is a land survey monument set by a land surveyor with registration number 13584 in that state. The marks represents: T14N R13W -> township and range 1/4 S3 -> the 1/4 corner between sections 3 and section 10. ------- -> horizontal line under the 3 and over the 10. .. S10 -> those dots are not there 1970 -> The year the monument was set The rest may be the surveyors initials and his registration number. I was trying to typographically show the 3 with a horizontal line under it and over the 10 which represents the East and West line between those sections.
  8. Public Land Survey System 1/4 Section corner should be right here: Topozone at that corner http://www.topozone.com/map.asp?z=12&n=519...u=7&datum=nad83 - jlw
  9. That is part of an extensive boundary surveyed in 1997 between a thing called the "Fort Ord Reuse Authority Lands" and BLM lands to the south and west. AP means Angle point or a bend in a line which generall trends to the Northeast and Southwest, it is on the "D" segment of the boundary. In 15S 2E Mount Diablo Meridian within an area that was never sectionalized being old spanish or mexican land grants. - jerry wahl
  10. I agree that it is a BLM boundary marker for some federal agencies land. I can give you more info if we have the general lat long. - jerry
  11. That type of monument is more commonly used for a Right of Way marker, and since it was along a road, that adds some evidence to that possibility. TR could be a lot of things, Town Road, some county, state or local road designation? jerry w.
  12. There are these situations where if you don't have the metal detecting capability, and you don't want to or can't dig everywhere, the only answer is to survey a position in accurately. There are a couple of ways to do that. One would be to use surveyinstruments from nearby stations. In this case it appears there are a few. This takes the proper equipment and surveying expertise to do. The other is to use some form of survey grade GPS (sub centimeter), or resource grade differentially corrected, probably to a foot or so. Both of those would require enlisting the help of someone who has that equipment and knowledge who might be willing to help on occasion. Otherwise you get close with the WAAS corrections. Do some averaging for say 10-20 minutes, then see if you can pick up anything with a good metal locator. - jlw
  13. Perhaps it has a slightly different designation. Just guessing. There was a General Land Office that did Land Surveys. There could be a U.S. Survey done by the GLO. anything is possible, so what might help narrow it down is the location, if you want to five a latitude and longitude, we might be able to narrow it down. - jerry wahl
  14. I am not very expert on leveling, but will take a first shot at this. 1) The superceded value shown was 13383. Note that was determined by vertical angles, not levelling and is shown to the nearest foot. That would also have been based on an old datum (NGVD29). 2) I believe that when the original work was done a preliminary calculation is used to 'mark' an elevation on the cap. That would be where the 13420 would have come from. It would be based observations done before the final network was computed, and so is some degree of an approximation. Again all on an earlier datum. (NGVD29) 3) The current elevation given is a conversion from the 13383 value and as is stated is the result of applying the vertcon datum conversion (not precise) to the NGVD29 value in 1) to come up with the NAVD 88 value 13390, whenever the datasheet was updated after that datum was instituted and computed for this area. - jlw
  15. I think this might be a picture of one: Example - jlw
  16. Perhaps I don't understand... Are you supposed to answer the question, or interpret the entry? Suitable for satellite observations from the point of view of NGS or any surveyor is just a slightly subjective opinon on whether the site is 1) able to be occupied by a GPS receiver, 2) likely to be able to receive reasonably good data. That involves no nearby obstructions that might give interference to GPS signals or reflections giving multi-path, and no extensive overstory, i.e. trees, that will cause problems with GPS observations. That is my take on it anyway, if you think you are to determine this factor, consider if the station is capable of being occupied with relatively open sky. - jlw I accept that the determination is not just counting tall objects on the horizon, but also X. Until I know what X is, I cannot accurately answer "Yes" for any mark that is not either on top of a mountain with no manmade structures and above the treeline, or on a desert with nothing above 5 feet tall for a few miles.
  17. Short answer is 'horizontal component'. All land surveys I am aware of measure and report distances and compute acreages using horizontal component of the distances. In the old days one way that could be done was to hold the chain level plumbed to the uneven ground by such means as a plumb bob. (with an exception described below, some surveys now report grid distances and areas). In the technology of the 20th century the distance may be directly measured on the slope, but a vertical angle is measured and by using almost basic trig the horizontal component is derived and used. Most total station instruments actually spit out the horizontal distance directly if you want it, or it is dumped into a data collector and reduced to horizontal later. Now with survey grade GPS this is harder to get to from the 3 dimensional vector one gets between points to the proper horizontal ground equivalent. People use a number of techniques to compute or closely approximate the equivalent horizontal ground distance to report for a land survey. One solution is now more common and that is to convert the lat long to some projection grid such as UTM but more often one of the published State Plane Coordinate Systems, and treat it like a 2d coordinate deriving a grid distance. You may see boundary descriptions with grid distances more often now as a result. Another solution is that many surveyors develop custom projections that are at the average terrain elevation of the project area and map the geographic coordinates to them, thus computing with those coordinates give you close to horizontal ground equivalent. Technically it is still not a perfect process. if the land varies much in elevation the question becomes horizontal based on what elevation. Anyway it is probably best not get into the technical details. - jerry
  18. I will add my 2 cents worth since I am a cadastral surveyor and have also been a geodesist. Cadastral Surveying is just a term for a land surveying specializing in locating and sometimes establishing boundaries of land, i.e. ownership boundaries. It is sort of 2d in that we think of the boundaries of lands being defined or shown on a map which represents measurements of directions and distances on the ground. Of course the ground is not flat, but legal descriptions of parcels act like it is. Large scale cadastral surveys must also take into account the size and shape of the earth, but are not usually concerned directly with the elevation of the land. Geodetic Surveying has more to do with precise absolute location of things, usually involving large areas and particular care in order to maintain high precision. Such surveys ares usually related to established control. The 'things' being located are sometimes boundary related but don't have to be. In order to perform geodetic surveying usually requires paying attention to the size and shape of the earth in a fairly scientific way. Actually not sure if that helps or not. These days with a lot of surveyors using GPS for surveying even some ordinary land surveying tasks are being done with 'geodetic' tools. jerry wahl
  19. There are some odd comments here and on another thread that someone said a third order station was not occcupied. Almost all horizontal control stations were occupied unless they are identified as an 'intersection station'. Thus some towers are intersection stations and were not occpied. But many belfries, etc. were occupied. A point would have been carefully set up below the spire or observable object to be directly below it and it could then be occupied by an instrument or lights. Other stations could sight the spire, or whatever. Anyway that's my sense of it as a surveyor that used to read a lot of datasheets. So my take on it is that in a sense both points are the 'mark'. A lot of old triangulation took advantage of existing tall structures in this fashion. - jerry wahl
  20. jwahl

    Gcs Term

    When conventional survey triangulation was performed, normally a station would be occupied by a theodolite at some point and angles turned from the nearest 'connecting' or intervisable stations. Work was often done at night to lights set on the other stations. This note seems to indicate that the point was sighted from several remote points and never occupied by an theodolite. Thus only a lightkeeper occupied the station. The lightkeeper would set up point and ignite the lights, and possibly on a schedule point them in different directions. Depending on the era of of the observations the lights could have been different things. NGS web site has a lot of pictures which probably show such things. No stigma, except it would mean that the point did not have the full geometric check one would have hoped for. - jlw
  21. If your guard post concrete is the remains of the actual guard post, there should be some evidence of a hole 2 feet north of it where the mark was. Unless it was set very shallow. And then there should definitely some evidence of the telephone pole west of that 2 feet. Typically posts or poles or the holes they came out of leave some kind of variation in the color or composition of the soil that can be seen as you dig carefully down through layers of more recent layers of vegetation soil and debris. A telephone pole would be set at leat 4 feet in the ground would leave behind a good opportunity to find some indication. - jlw
  22. Unless I misread the data sheet, no one has responded to the thing being right next to a telephone pole TO REACH FROM THE LEHIGH VALLEY RAILROAD STATION IN RUSHVILLE-- PROCEED 1.9 MILES NORTH ON AN IMPROVED ROAD, TO SITE OF BENCH MARK. BENCH MARK IS 68.0 FEET EAST OF THE EAST CORNER OF AN ABANDONED BRICK BUILDING, 28.0 FEET WEST OF AND ABOUT 1.0 FOOT ABOVE THE CENTERLINE OF ROAD AND 2.0 FEET EAST OF A TELEPHONE POLE. IT IS 2.0 FEET NORTH OF A 4X4 INCH WOODEN MARKER POST. MONUMENT PROJECTS 0.4 FOOT. There is high resolution photography available from NYS NYS Ortho Imagery The 2002 stuff is 2 foot and identical to what was just posted. There is also 1998 Color, fairly low resolution. It appears from the shadows that there are power poles on the East side of the road. A telephone line or pole could have been to provide lines to the structure, whatever it was. If the pole was torn out, another possibility is that the mark may have been damaged or removed also. However the dates are problematic. If UPSQ really found it in 2002, some or all of this imagery is of that date or earlier, the pole should show. The area appears to be on the edge of cultivated area which varies in appearance in each set of imagery I can find. It is possible the mark was damaged or destroyed by farming activity, however the later images appear to show cultivation 'around' and excluding the site and not over it. Trees often grow up around old houses, schools, buildings, etc. and so the clump of vegetation shown in the pictures is consistent, it is just hard to see clearly in all the ortho's. Virtual work like this can be useful, but sometimes difficult. If it were able to see the same clump of vegetation in the ortho's we could probably predict the building footprint and measure the 68 feet and see where that fits the road, but that is going to be less definitive than on the ground debris unless we find photography that shows the building more intact. In the later images, an area north of the trees appears almost fenced off. So there is also the possibility that the main structure was there and the location with the trees and brick debris is an outbuilding or dump area. Like I say, virtual work and speculation leaves a lot to be desired and most of those thoughts can be quickly dispelled by 10 minutes on the ground. - jlw There are sources of agricultural photography, that go way back, I don't remember the link, but I will try to track it down. (not online here) APFO source I am checking other sources now. USGS shows a number of images, but again they have to be ordered. Ontario County shows ability to order imagery back to 1969.
  23. There are some confusing elements that you have probably considered. 1) The road direction is just west of north maybe N. 20d W., the call is 68' East of the East corner of an abandoned brick building. I would at first take that to mean east and not in a direction along the road but more toward the road. The quad has the structure far enough away from the road for that to still fit. 2) the call for being just East of a telephone pole. Is there anything like that in the area? There can be concrete around a lot of things, mailbox posts, etc. I know there is always some ambiguity about directions in descriptions. It might be useful to check the description of another mark along the same line north or south and see how the terms East are used, along the road or basically map east. - jlw
  24. Give me a lat long if you get a chance... - jlw
  25. Another tool which can be used to approximate township range meridian and section and works in western states is derived from a program called TRS2LL. A web interface can be found here: TRS2LL interface the part that goes from lat long to the description can be found here: Latitude and Longitude entry UTM entry here: UTM entry It is sometimes time consuming to find the townships and ranges on continuous coverage quad bases like topozone or terraserver since that into is mostly on the map collars which are cut off. - jlw PS For instance Mono Pass is at 37-25-30 / 118-46-21 which plugged into the second link above yields and extensive feport which begins with this: Latitude/Longitude 37.4250°N, 118.7725°W ( 37°, 25', 30.0" N; 118°, 46', 21.0" W ) The legal description is: California, Mt. Diablo Meridian T6S,R29E,sec14 UTM zone 11 (X,Y) 343165 , 4143496
  • Create New...