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The USGS Miscellaneous Publication #1, 1875, pg. 14, states that the elevation at Fairplay (9964 ft.) was determined by a railway survey. Page 63 states that the 9964 ft. elevation was at the "Doorsill of Sentinel office before fire of 1873". I suspect that the elevation on the side of the courthouse was informal, and was simply painted there for public information.

Is that paint underneath the "U.S."? Almost all of the King, Hayden, Powell, and Wheeler survey marks were made for mapping purposes, and were folded into the USGS in 1879 when all the Western Surveys were consolidated. Very few of them were considered accurate enough to be used by the Coast Survey and hence aren't in the NGS database. Wheeler published descriptions of some of his marks, and the USGS belatedly published the triangulation of Powell, but I haven't found sources for King or Hayden that contain descriptions of their marks. The best reference I've found so far has been Gannett's 1895 Bulletin No. 123 of the USGS, and that only contains the triangulation stations, not the bench marks. As a matter of interest, I spent some time trying to figure out the relationships between the surveys and what was surveyed by whom. Ultimately, I intend to make a wiki page from it. Here is a preliminary map that I made showing the surveys and the areas of overlap:

The Department of Interior's Geological Survey *is* the USGS. Maybe they reset their own disk, for some reason. It is weird, though.

PV0523 is what is called an "intersection" station. (See this wiki article.) There was never any mark, if you mean some kind of brass disk. It means that the position was determined by sighting on it remotely from other known locations, but no one ever went to the top of the tower and established a mark or took accurate measurements. If you look at the data sheet, there are three things to notice: 1) HORZ ORDER - THIRD, 2) the wording in description THE POINT INTERSECTED WAS THE APPROXIMATE CENTER OF THE TOP, and 3) MARKER: 55 = TOWER. 1) Third order accuracy is a low accuracy -- sufficient for mapping, but not usually sufficient for geodetic or accurate surveying purposes. Most triangulation stations will be GPS, first order, or perhaps second order. Third order usually means that station was an intersection station, or perhaps was reset from reference marks after being damaged or displaced. 2) When a station description says "the point intersected", it is a pretty conclusive indication that the station will not be a disk, but will instead be some kind of natural or man-made landmark. 3) The marker is the tower rock formation itself, not a brass disk or other artificial mark. If you look at the date of the 2007 recovery report, it is a GEOCAC report, and on geocaching.com you can see that it was reported by wister6813. Wister6813 correctly shows a photo of the rock formation rather than some kind of disk. If I had any complaint about the recovery report, it's that Wister6813 presumably reported the position as suitable for GPS, which isn't really true, because a) Wister6813 couldn't tell what the conditions are at the peak from his/her position a few miles away, and there is no "there" there that would allow precise GPS measurement of a position.

I've flagged those initials so that recoveries must be manually reviewed and assigned to the correct identity. It may be months before the NGS posts the recovery reports, but once you know that the datasheets have been updated, you can check the statistics to verify the correct assignment. Let me know if they show up under the wrong identity.

Ok, you're in. Usually, it works without any effort on your part. I'm not quite sure why you weren't included already, because I try to identify the initials on GEOCAC recovery reports without being asked. Usually I see a new unidentified recovery report, and look at the corresponding log on Geocaching.com. If I can uniquely identify someone who logged on the same date as the recovery report, I assume it is the same person and I cross-reference the initials to the geocacher. I don't automatically include geocachers in the statistics list unless they also report to the NGS, because (a) I have no way of knowing who they are, and ( the list would be too long, and it would include many people who probably don't care about the statistics anyway.

It sounds like you've searched heroically. It was possible (although not likely, given the number of prior recoveries) that the "southwest" direction was mis-stated, but the one certain thing is the rock outcrop. If the only rock outcrop is in the location you originally searched, it seems likely that the mark is lost or very well hidden.

I vote woth Holtie and MLoser. It is possible that the direction was incorrectly stated as southwest of the pole when instead it should be northwest. The two images below provide a strong argument. The first image shows a radius of 108.2 meters around a pole on the grounds of the old fort. The second image shows the USGS quad superimposed and georegistered to the same image. The BM on the USGS quad, at elevation 408 feet, lies almost directly on the 108.2 meter radius of the pole, and the datasheet states that the elevation of FH0806 is 407.5 feet.

Ah, you know, part of my process generates a list of unidentified reports, but in order to prevent seeing the same long list month after month, I have a filter that only lists the recent ones. I occurs to me that because of the large backlog, all the unidentified reports got filtered out because they were all more than 3 months old. I remember thinking "huh, funny there was nothing new in that list", but didn't give it any more thought. For safety's sake, I never automatically identify reports filed under two-letter initials unless there have been other reports under the same initials in the same county. Usually I can manually identify the majority of the new ones, but I only do that if I see them! I'll rerun that part of the process so that I see all the reports from May forward. edit: The statistics have now been updated.

This once, yes. You can obtain a 3 Mb ZIP file of the datasheets at http://www.holoscenes.com/dsarchive/Sep10.zip. The reason I say "just this once" is this: from past experience, providing stuff for free encourages people to expect it, and it soon becomes a burden on me. I don't want to feel obligated to add extra work to my monthly process, and I don't like to hear complaints if I forget to do something or don't have time to do it as quickly or as often as people would like. Also, the more data I provide, the less freedom I have to modify the process or the format. So yes, you can have the datasheets I just obtained this month, but in general for the future, probably not.

Yes and no. Is there an easy way? Not that I know of. A number of years ago, the NGS FTP site used to have a download of all datasheets updated in the past month, but that hasn't been supported for quite a while. I haven't looked lately to see if a simple download is available again. The FTP site does have downloads of updated states, but I don't think they create all the state files at the same time, and the downloads seem to have a lag -- they are not immediately available at the beginning of each month. I wrote a 'bot that simply uses the datasheet retrieval by date page and walks through all the states looking for all datasheets updated in the last month. There are complications related to the limits on the number of datasheets that can be retrieved in one request, and of course, 'bots should try to avoid overloading the server. The process sometimes takes a few hours, which is why I only do it once a month.

The September statistics are available on the statistics page. The maps and counts by county have been updated also. There were 605 datasheets updated with GEOCAC recovery logs. The most recent recovery added to the datasheets was dated June 24, so there is still a backlog of updates remaining at the NGS. It looks like TheBeanTeam bagged the five westernmost stations in the 48 contiguous states in June. Congratulations!

I re-read the Ludlow report, and it is clear from the report, and also from the time differences, that the chronometric time referenced St. Paul, Minn, which was also the point of embarkation for the expedition. However, I couldn't find any mention in Ludlow's report of the exact location in St. Paul that was the basis of the calculations. So it is next to impossible to re-crunch the numbers. Perhaps there was an assumed location in St. Paul. In the Lake Survey report of 1872, the astronomical station in St. Paul was located 451.3 feet east and 48.4 feet south of the southeast corner of "the new custom-house on Wabashaw street". The position of the southeast corner of the custom-house was used in several subsequent publications by the Army. The position was determined to be 40m 10.15s of time west of the Lake Survey observatory in Detroit, or 1h 4m 10.14s of time west of Washington, D.C. As of 1873, the Army used a value of 5h 8m 12.12s for the longitude of Washington, D.C., so the longitude of the southeast corner of the custom-house in St. Paul would have been 6h 12m 22.26s, or 93° 05' 33.9". That is also the value quoted in several other Army publications. There is a non-published PID PP2512 with the name ST PAUL CUSTOMHOUSE at N 44° 56' 44.8", W 93° 05' 41.1" NAD83. Unfortunately, if you correct Wood's coordinates based on the St. Paul custom-house coordinates, it pushes Wood's station even further west of the crossing. Most of the Ludlow report's longitudes are either 00 seconds or 30 seconds, so it looks like Wood may have computed most longitudes to the nearest half-minute or sometimes quarter-minute of arc. If that is the case, the published longitudes have a wide error.

Astronomic Lat = Geodetic Lat + Xi. West Astronomic Lon = West Geodetic Lon - Eta / cos(Lat). To account for the Airy meridian, subtract another 5.64 seconds. So the correction would be 9 seconds, making the astronomical coordinates N 47 33 40.61, W 108 21 13.12 relative to Airy. That actually increases the discrepancy by about 0.1 mile.

Longitude was uncertain at that time. First, all the longitudes were astronomical longitudes, and were referenced indirectly to the Airy meridian at Greenwich, which is west of what is now accepted to be the zero longitude. The report you found shows that Wood didn't have access to telegraphic longitude, and needed to rely on a chronometer instead. Chronometers were very hard to keep accurate when transported over land, so I'm not surprised that his determination might be off by a mile. In general, most of the West was referenced directly or indirectly to the Salt Lake Pier longitude established by George Dean of the Coast Survey in 1869. In 1873, Lt. Wheeler established an astronomical station at Bozeman, MT, connected by telegraph to Ogden, Utah, and determined Bozeman's longitude to be W 111° 02' 36.64". On page 36 of the Ludlow report you linked to, you find a recommendation to establish "an Observatory on Mount Washburne, with a wire to Bozeman," meaning that a tie into the growing telegraphic longitude network could provide an accurate basis for mapping. It is likely that Wood's datum was Wheeler's, and Wheeler had Salt Lake at 111° 53' 42.9", which is about a quarter-mile west of the modern location. edit: Using Wheeler's published coordinates for the Bozeman station (111° 02' 36.64") and his description of the station location (about 100 feet northeast of the grave of Bozeman, which is in Sunset Hills Cemetery), it looks like Wheeler's Bozeman coordinates are about 0.9 mile west of the NAD83 coordinates. Assuming that Wood's longitude was based from Bozeman, that explains most of the 1 mile discrepancy you found.

Be careful about where you attempt to obtain one. You can buy new ones as LSUFan mentioned. If you try to obtain an old one, you may not personally damage a marker, but it's highly likely that you would buy it from someone who did. That would also be called receiving stolen property.

The second problem you mention is much easier, because you can use the "Forward" program at this link to compute coordinates at a given radius and direction from another point. Simply choose three directions from your central point, and you get three points. For the original problem, in virtually all the practical cases, you need to convert the lat/lon coordinates into x/y map coordinates of some kind, UTM or State Plane being the most obvious, since your GPS can do the calculation for you. The simplest method involves some graph paper, pencil, and compass. You can use that method on the USGS quad map sheets. If you have GIS software, you can create a map containing the three points, add circles centered on the points, and then get the coordinates of their intersection. Different mathematical methods will vary in their tolerance to errors, which is important because the distances given to you are approximate, which means that the three circles won't perfectly intersect, which means that mathematically speaking, there won't be an exact solution to the system of three equations. In the example you gave, you can see that there is no exact solution, because the three circles don't intersect. This is an especially bad example, because the circles from points A and C don't actually meet anywhere, the circle around A is entirely contained within the circle around C. It is hard to see, but you can compute the distance from A to C using the "Inverse" program, which gives you 0.1695 miles. Since circle C is 0.28 miles, that means that it is 0.1105 miles from point A at its closest. Since the circle around point A is only 0.11 miles, that means that there is a gap of 0.0005 miles (2.6 feet) between circle A and circle C. Most likely, the puzzle author expected you to enter the three waypoints, and use your GPS to guide you to based on the ranges from the waypoints. That may be how they created the puzzle in the first place -- standing at the cache location and using the GPS to compute the ranges to three waypoints, not realizing how bad the configuration was mathematically.

Just to make sure we understand the problem, are you saying that you know the locations (a,, (c,d), (e,f), and the distances R, S, and T in the diagram below, and you are trying to find the coordinates (x,y)? Technically, that problem is called trilateralization. Next, are you looking for mathematical formulas so you can calculate it yourself, or are you looking for some web site or program that does all the calculations for you?

Sometimes you get excited to see an old mark monumented 1897, and the description says it is a standard bronze disk placed on the mountain peak accessed by helicopter. You realize there was a typo and the date was actually 1987, not 1897.

The August statistics are available on the statistics page. The maps and counts by county have been updated also. There were only 2 datasheets updated with GEOCAC recovery logs, and those appear to be backdated reports for June 2009 recoveries. It looks like the NGS is still working through their backlog of updates. There were about a hundred recovery reports from a surveying firm dated July 27th , so at least some updates are getting loaded.

There are 3141 county and county equivalents in the US. Some of those are incorporated cities which are not within the bounds of counties, for instance Baltimore, MD, Washington, D.C, and numerous cities in Virginia. The number includes the boroughs in Alaska and New York that are equivalent to counties. The NGS also has datasheets for other territories and protectorates like Guam, Virgin Islands, American Samoa, and others. There are 78 county equivalents in Puerto Rico.

That's good news, Paul. I guess we can look forward to a big jump in the numbers at the end of August.

Depending on how you georeference the images, there can be a huge difference between orthorectification and georeferencing. In terrain that has high relief, the difference is large. See the attached PennPilot image that has been orthorectified. The higher elevations get shifted inward toward the axis of the photo, and the lower elevations get shifted away, in a very nonlinear manner. If you are trying to get coordinates from the image, basic georeferencing might be off by hundreds of meters. In the orthorectified photo, even with estimated camera parameters, the coordinates are generally accurate to within a few meters. Click the thumbnail to get a larger image (but still about 1/6 of the full scale image). Notice what looks like distortion, which is really correction for the original photo's distortion.

In the 30's, the federal government's Agricultural Adjustment Administration did a fairly widespread aerial survey project, one of the first in the nation. I know that Pennsylvania scanned and put a large quantity of photos online at the PennPilot web site. It would be nice if more states did the same. I've used them for mapping historical railroad rights of way. Some commercial web sites also have old aerials available. One consideration is that the photos are not ortho-rectified, so you can't get accurate positions from them unless you process them with software such as Grass. But the raw photos do help you visualize the landscape and would get you in the correct neighborhood if you can spot other landmarks.

Yep, the last month that had a lot of updates was May (the statistics I posted at the beginning of June).