Bill93

As previously mentioned, the dedication of the Bilby tower that was rescued from oblivion will be held in the home town of Jasper Bilby in southeast Indiana. A public invitation and schedule is posted on the professional forum. Dave Doyle is a featured speaker. Some prior threads: George reports a tower found Some links to tower history A thread with more links

In that thread JS2170 (GC page) (NGS sheet) is discussed. Is anyone near enough Yolo County, CA to get a picture? Should be easy to find with good coordinates and a 1999 to-reach.

Jerry Penry, a professional who frequently comes up with topics of interest, has published an article about USGS bench marks and the various datums they were on. He is building a list of codes stamped on USGS disks. He would welcome any additional codes or information relating to them. See his post at the professional surveyors forum for the links.

I looked almost 10 years ago for the lower disk, and couldn't find enough evidence to be sure whether the culvert was under the present road or had been removed. I suppose I should have logged a NF. It was quite unusual to have two marks so close horizontally, even though they had 35 feet vertical separation. The Hwy 100 extension follows the old RR route out of town, starting from somewhere just west of I380. We've been using a piece of 100 for years, out to Edgewood Rd, while there was a debate about environmental impact of various routes and about funding for the extension. It will cross the river before turning south. Today they removed enough concrete I'm pretty sure that the upper disk is gone, somewhere in the rubble pile below.

I took this picture tonight. Some concrete is already down, but the straight-on profile of the top looks undisturbed. NJ0547 is/was on the near end of the top of the old RR abutment.

>marks near some of the monuments I'd be somewhat cautious about "non-tourist-like" activity around famous memorials and buildings. I recall getting questioned one time about why I was writing down the info from a disk in a retaining wall beside our local federal courthouse. People from the general public were sitting around chatting 20 feet away and I crossed no marked boundaries to get there. I had no camera or GPS. The guard was out of the building and on me in 30 seconds, and it took a while to talk my way out of there. And be sure you don't have all your benchmark hunting gear with you. No pocket knives etc on federal property.

There's always the possibility that it was left over from a project. There seem to be a lot of stations with similar names. The fact that there is no date would lend support to the idea. Maybe somebody stamped a bunch of them in preparation for a project and was going to put the date on them when they were set. The stamping looks cleaner than the cast letters, like it had been stored somewhere it could get wet or dirty at one time, but not after stamping.

Yes, a photo would help us be assured we have the all the information. Does it have a year stamped? That would be important confirmation if any description was found to otherwise match. I think one would need to check out all the related designations, because sometimes the stamping is not the full designation.

You're right that there aren't a lot of dedicated hunters. I suspect a lot of formerly active hunters ran into the same problem that you and I have - you need to travel a long distance to find marks you haven't already hunted. The number of views on some threads is encouraging, however, in that it still shows interest by more people than that.

You could also have a grid vs ground issue. Does the "metadata" from the survey tell whether they are using a state plane coordinate system, using distances on the ellipsoidal earth model, or surface distances? If state plane or a low-distortion custom projection, the azimuths may be relative to that grid and not geodetic.

A typical practice would be to set 2 to 4 nails each 2 feet from the point (more distance if that isn't enough working room), remove the old marker, and place the new marker to match the 2 ft distances. That is usually more accurate than measuring from a greater distance. With care, the new marker should be within 0.005 ft (1/16") of the old one. This procedure shouldn't cause any discrepancies. If there are differences between old and new surveys, then professional judgment based on all the evidence comes into play. Ideally, the two surveyors should discuss why they got different results and see if they can come to agreement.

If you're looking for the land surface that's the highest, it may not help a lot to know where the highest bench mark is. They wouldn't likely have sought out that point to place a disk. For the highest point, you might try Google Earth 3-D view to select candidates and then confirm with the topo map which is highest.

Some who visit this forum may find the article interesting http://www.dnainfo.com/new-york/20131218/astoria/map-found-overseas-may-offer-rare-glimpse-of-revolutionary-era-new-york

Back in 2005, BuckBrooke (Buckner Creel) created a page and gave a link (about 3/4 down on page 1 of this thread). It was on a university web site where he was a grad student. After this many years, I'm not surprised if he's moved on and the university cleaned out his account. That username has not logged into this site in the last 2.5 years.

The reverse azimuth might imply that the center was fixed and the outer circle would have something attached and rotate to read the azimuth at an index mark on the center piece. That would yield normal azimuth values. But I don't see the index mark and can't tell if anything rotates.

Counterclockwise azimuth?

Photos via Surveyors Historical Society: https://plus.google.com/photos/109209179919974559773/albums/5935100767612928177

>planned on removing it and sending it in to NGS and then at the end of the project a reset would be placed So what will hold the elevation in the meantime?

One could hope, but not expect, that they would be able to keep the disk intact in place, or else do an official RESET. Chances of either are slim. You might ask at any surveying companies in your area to see if they are interested in having this mark or a reset available for future use. If flood certificates are frequently done in your area, and especially if there aren't a lot of readily accessible vertical control marks in the area, they might care about it even though the bridge contractor doesn't. Professionals might be able to save it when you can't. That's more important than a souvenir.

The linked thread on the surveyors forum now says NGS will set a commemorative disk, and there will be a formal dedication, probably in June 2014. So I needn't have worried - the Surveyors Historical Society does things up right.

The tower is now up just south of Osgood, IN. Pictures and discussion in this thread on another forum. I'm not sure they have it over a disk, but have inquired. If they need a disk, does anyone have a C&GS tri-station disk they would donate? (Cross reference an additional thread here about Bilby)

My criterion for finding bogus logs would be: any log (including Notes) containing the words "wrong disk" OR any mark that has a Destroyed report followed by Found logs without a picture of the correct disk or intersection station. Even then, some judgment will be required, and I'd rather risk a few bogus ones than delete a good one. Some of the other proposed methods would inadvertently select more correct logs.

Technically if a point is rebuilt, it isn't the same point - it's destroyed. Practically, I'd guess that a completely rebuilt cupola, dome, or spire won't be close enough. But if a church spire or cross is removed for re-shingling and replaced without structural modifications, it probably is within an inch or so, and may be "good enough" for the purposes intersection stations were/are used for, when observed from triangulation stations at typical distances of a few miles. The spec for third order I believe was 1:10,000 relative to other network stations (2-sigma or 95% confidence?), but most observations would have been good to maybe arc seconds, say 1:200,000 precision or 0.3 inch per mile and small changes would be detectable if anybody re-observed to that precision (which NGS won't be doing). That's a totally unofficial guess, of course.

There are some pictures on this thread http://surveyorconnect.com/index.php?mode=thread&id=221840 Matt was on the measuring team that won the contest. Participants used four different historical measuring methods to see who could come closest to modern measurements. I didn't get pictures of that, unfortunately. Bill & Matt I took my turn during the setting of a spike to mark the location of Mason and Dixon's observatory. This was 700 or 800 feet south of the famous "Stargazer's Stone" which was actually their backsight or azimuth mark.

To answer the title question, obviously it was not placed by USGS, USC&GS, or NGS, but rather is a benchmark placed by Clark County. They had the option of collecting their data in accordance with NGS procedures and adding it to the NGS data base. If you click on "nearby benchmarks" you will find some other Clark County disks with 5-digit designations that were in the NGS data base when Geocaching took their snapshot around 2001. See for instance http://www.geocaching.com/mark/details.aspx?PID=RD4255, number 16391 I don't see 16499 (nor 16488 in case I read it wrong the first time) in that list. Neither do I find it in the current NGS list. The county probably only went to the trouble of submitting data to NGS for a fraction of their benchmarks. Even so, there are a lot of benchmarks in the NGS list within a very few miles of that location.