KU4051 - An interesting Problem

[Papa-Bear-NYC]

Last week Harry Dolphin, Andy Bear and I went along the New Jersey Palisades to find station KU4051 "HIGH POINT". Like many of the triangulation stations on the Palisades, it was set in 1930 and is right on the cliff's edge (acrophobics need not apply). Due to it's location overlooking the Hudson and the City of New York beyond, the Palisades has been a favorite place for triangulation station since the 19th century.

 

Well, last week we had to leave before finding the station due to lack of daylight and time. We had spotted one reference mark as we approached and a witness mark (a chiselled cross in a square) a few minutes later.

 

This week I came back by myself (Harry and Andy went to south Jersey), but this time I had plenty of time, plus my new Radio Shack Discovery 3300 metal detector.

 

Well I dug and I probed and I scanned and I measured from reference marks but still there was no station disk. Every so often I would take a break from digging and go after another reference disk (there were 5!) I would measure off with my tape from the "presumed" location of the station and using my compass would get to an area. Then I would scan with the detector, and not once, not twice, but three times, this "diversion from digging" resulted in my finding another reference mark. This station has no less that 5 reference marks (of which I eventually found 4) but I almost believe it has too many reference marks but too few stations marks (as in zero) . Interestingly, these 3 new reference marks were all on buried rocks in a level area - each an inch or two below dirt and leaf litter. One was set by Westchester County - a disk I had not seen before. So as my confidence in the metal detector at finding reference marks rose, my confidence in it's ability to find the station mark fell.

 

But with each new reference mark found, I would have another point to measure from, so I would measure back towards the station and find a new spot and dig some more, or I would find an old spot and scratch my head. And now I could start to triagulate with two reference marks at one time. But that was hard with just one tape and the inevitable uncertainty of measuring through uneven tarrain with undergrowth, although to be honest, this area was not as nearly bad as many I've see.

 

The problems with measuring with the equipment at hand was uncertain bearing and uncertain distance (that's about it, right ). Sure the tape is accurate to a sixteenth of an inch, but that's only if you lay it on a flat surface and stretch it tight. When I do get a measurement between two known points through the woods, I'm almost always off by sometimes a foot (in say 40 feet). The bearings can be worse as the distances grow. I know surveyors can measure angles very accurately, but they still must use a steel tape and I don't know how they get the accuracy they claim. Now-a-days I guess they use lasers or something, but in 1930 they used tapes just like me.

 

My only idea is to go back with one or two others, and try some simultaneous multi-tape measurements. That should eliminate the bearing problem, but not the distance errors.

 

BTW: I trid the GPS measurement idea which has been discussed here lately, but got considerably less accurate results. It would fluctuate 2 - 4 feet. Pehaps it's the satelites here, but I gave up on this.

 

So I would welcome any brilliant ideas for me to try next. Or volunteers to join me if (when) I go back. Just bring your tape measure and metal detector. And a little magic would help if you have any.

 

It was nevertheless a great day to be out and some beautiful views to boot.

 

Here's some reference marks for your enjoyment (the last is a witness mark "2 1/2 paces" from the station):

 

[+Harry Dolphin]

Wow, Papa-Bear! I'm impressed!! Four of the five reference marks! Must have been might cold on the Palisades. Around here, the ground is frozen. (Northwest Jersey - geocaching event in Sparta.) I have been surprised with the accuracy of the coordinates for the benchmarks atop the Palisades. HAN and LINDY were both within a few feet. I would expect that HIGH POINT is as well. The problem was digging through a lot of soil to find the disks. I am surprised by the soil build up atop the Palisades. The possibility does exist that the disk is missing, but, then, there should be a hole in the rock. As you noticed, I have a bit of a scorched earth policy when digging. (And I did get poison ivy on my arms!) Two reference marks should be enough to determine that we are in the right location. (There are probably a surprising number of circles and crosses carved into the Palisades.) I suspect that we were in the right location.

Did you get GPS coords for the reference marks that you found? We should be able to triangulate to make sure that the coords for the station are accurate. I actually do have a bad fear of heights! But Dolphin and Bear would be glad to assist in another search. After LINDY, anything is possible!

[2oldfarts (the rockhounders)]

I would suggest that you take 3 pieces of heavy string or cord along the next trip. They need to be 8 to 10 feet in length.

 

Go to the 1st RM (Whichever has easy access) and set a way point. Do a go to for the way point. when the bearing is correct and you are too close to the RM, place 1 end of one of the pieces on string on the ground. Anchor it with a rock or something. Now move past where the station should be and line up the bearing again. Draw the string snug and anchor that end.

 

Repeat for 2 more of the RMs. Where the 3 strings cross will have the highest probability of being over the station mark.

 

Good luck on your next trip. We would enjoy being there to assist you in your endeavor.

 

John

[Papa-Bear-NYC]

Two reference marks should be enough to determine that we are in the right location. (There are probably a surprising number of circles and crosses carved into the Palisades.) I suspect that we were in the right location.

Hi Harry.

There's no question but that we are "there", else there wouldn't be 4 marks pointing at the same locale. Add the circle with the coss and it's a "gotta be". I am assuming there may be just a hole there now. I think the metal detector would have actually found a disk, given it found 3 other disks.

 

Did you get GPS coords for the reference marks that you found? We should be able to triangulate to make sure that the coords for the station are accurate.

I only took a waypoint of the first RM we found last week. But after difficulty in using a GOTO to point back to it, I gave that up. We should assume the station mark location is more accurate the the RMs by far. But even if they're off by a foot or two we should still find the mark.

 

I actually do have a bad fear of heights! But Dolphin and Bear would be glad to assist in another search. After LINDY, anything is possible!

Well this is the last unfound mark on the Palisades as far as I know. So we'll keep trying. I'll see if we can work out a date for a return engagement.

[Papa-Bear-NYC]

I would suggest that you take 3 pieces of heavy string or cord along the next trip. They need to be 8 to 10 feet in length.

 

Go to the 1st RM (Whichever has easy access) and set a way point. Do a go to for the way point. when the bearing is correct and you are too close to the RM, place 1 end of one of the pieces on string on the ground. Anchor it with a rock or something. Now move past where the station should be and line up the bearing again. Draw the string snug and anchor that end.

 

Repeat for 2 more of the RMs. Where the 3 strings cross will have the highest probability of being over the station mark.

Hi John

Sound like a good method, definately worth a try. It would also be a check on the GPS if the second bearing (the one past the station) also agrees with a line-of-site through the first end of the string and the RM. Some sticks to use for alignment would be useful. Be aware that the station is near the cliff edge, so one cannot go too far past it.

 

Good luck on your next trip. We would enjoy being there to assist you in your endeavor.

 

John

I'd like to take you up on that. I'll email you with schedule suggestions.

[+Holtie22]

Here's a method for getting a distance-distance intersection with a single tape and one person: Anchor one end of the tape on the first RM, for example with a rock or nail (as an alternative you can anchor it beyond the mark in such a way that an even foot coincides with the mark). Take the sum of the two distances from the RMs you are using and find that sum on the tape (plus the even foot if you used the alternate anchor above). Anchor the tape so that the sum of the distances coincides with the second RM. Now find the point of the first distance on the tape, and holding that point, pull the tape taut from both anchors. The closer you are to a right angle between RMs, the better your results will be. Accuracy can be increased if you have more people to monitor the anchors. If steep slopes are involved, plumb bobs can be employed to keep the tape level.

[Papa-Bear-NYC]

Here's a method for getting a distance-distance intersection with a single tape and one person: Anchor one end of the tape on the first RM, for example with a rock or nail (as an alternative you can anchor it beyond the mark in such a way that an even foot coincides with the mark). Take the sum of the two distances from the RMs you are using and find that sum on the tape (plus the even foot if you used the alternate anchor above). Anchor the tape so that the sum of the distances coincides with the second RM. Now find the point of the first distance on the tape, and holding that point, pull the tape taut from both anchors. The closer you are to a right angle between RMs, the better your results will be. Accuracy can be increased if you have more people to monitor the anchors. If steep slopes are involved, plumb bobs can be employed to keep the tape level.

Thanks Holtie

 

I had actually thought of that. The slope is not steep - in fact it's almost level, so the affect of that should be minimal. The real problem is there are lots of small trees and bushes in the area so it would be difficult to do the stretching and and moving the tape to get both legs straight and taut.

 

I could always clear cut the area with a chain saw , but seriously, I would actually have to thread the tape down through the trees and bushes and then back to the second RM. So I would almost need to know where the two legs of the triangle went before starting. But it's well worth a try and with a little cutting of some key bushes with a hand saw I might get a workable triangle. And with 3 usable RMs (the 4th would involve a tape hanging out past the cliff edge) I could make 3 such triangles. The advantage is also that this method will not depend on errors in the bearings, but it will be subject to errors in the original distance measurements (which I am always suspicious of).

 

Thanks again. Just having you suggest this makes me rethink why I didn't initially try it, so maybe I can work out some solutions to the problems.

Edited December 11, 2006 by Papa-Bear-NYC

[ArtMan]

Interesting story. Best of luck in finding this one.

 

It's noteworthy that the mark is in New Jersey but was set by the City of Yonkers, New York, which is across the Hudson River from this location.

 

I suppose the Palisades was used to provide a uniquely visible vantage point, high above other possible sites that are in or closer to Yonkers. Perhaps someone with better knowledge of the area could comment?

 

-ArtMan-

[Papa-Bear-NYC]

Interesting story. Best of luck in finding this one.

 

It's noteworthy that the mark is in New Jersey but was set by the City of Yonkers, New York, which is across the Hudson River from this location.

 

I suppose the Palisades was used to provide a uniquely visible vantage point, high above other possible sites that are in or closer to Yonkers. Perhaps someone with better knowledge of the area could comment?

 

-ArtMan-

Yes, these triangulation stations were used by New York City and other east of Hudson cities from the 19th century on. The station HIGHWOOD 2 (KV4020) dates from 1867 and was used in the 1898 and 1903 triangulation of NYC. PALISADES (KU3890) dates from 1898. In fact they are more useful to those parts to the east (NY) than to the west (NJ) due to the shape of the land.

 

This is not uncommon. I've encountered marks set by Canadian entities in Maine and Vermont. You need good triangles and you get them where you can. Check this one out QH0621.

Edited December 11, 2006 by Papa-Bear-NYC

[+Harry Dolphin]

One of the best names for a bench mark that I've seen! SEARCHME

[+PFF]

If there is line-of-sight, and if you have a couple of LASER devices (pointer, measuring device, etc.), try shooting beams from two of the reference marks, in the exact direction indicated by the arrow on the disk. When the beams converge, you should find the main station.

 

-Paul-

[Papa-Bear-NYC]

If there is line-of-sight, and if you have a couple of LASER devices (pointer, measuring device, etc.), try shooting beams from two of the reference marks, in the exact direction indicated by the arrow on the disk. When the beams converge, you should find the main station.

 

-Paul-

Thanks Paul

 

I don't have access to laser pointers, but there is line-of-site. We can certainly lay a tape down and site along it. But I see two problems (even if we had lasers): 1) It was my understandingt the arrow on a disk was a rather rough direction indicator. Maybe at 40 feet it doesn't matter that much. 2) It's pretty hard to take a siting with respect to a mark on a ground level disk. You would practically have to lay on the ground to even have a chance. That's why surveyors set up a tripod and do eye level sightings.

 

But it's one more idea to try. If I try every idea given on this thread I will have a better chance than not.

[ArtMan]

One of the best names for a bench mark that I've seen! SEARCHME

I noticed that. I think it's across the river from NYAHNYAH and just down the road from NOWAYJOSE. :-)

[+Klemmer]

Can't you just imagine the conversation:

 

FIELD GUY TO TEAM LEADER:

"What's the name of this mark going to be?"

 

TEAM LEADER TO FIELD GUY:

"Search me."

 

FIELD GUY TO TEAM LEADER:

"OK, thanks."

 

Edited December 12, 2006 by Klemmer & TeddyBearMama

[Papa-Bear-NYC]

I returned yesterday for the third time and spent another 2 1/2 hours searching, but without success. In preparation I calculated the locations of all the RMs (with FORWARD) as well as distances and bearing between them (with INVERSE). As a check I measured these on the ground and the distances were within an inch or two and the bearings (after applying magnetic declination) agreed with the line-of-site. This not only confirmed the validity of the box score information, but also confirmed the accuracy of the tape measurements and the compass bearings. I also cleared all bushes and vegetation from the respective line-of-site swaths from the RMs to the station locale. This made sighting and tape measurements easier.

 

I tried a variety of strategies to locate the station.

 

1) Double tape method: I brought two tapes and measured off the distances from two of the RMs simultaneously. The intersection point of the tapes (both straight and tight) sahould have been the station. I did this twice from two combinations of RMs. The two result points were close but no station was found.

 

2) metal detector. I found all the RMs (except the one on an exposed rock ledge) with the detector. I scanned the entire presumed location area to no avail.

 

3) Set waypoint and GOTO. This was not successful. Although there was no leaf cover, there were numerous trees which resulted in highly variable and unreliable results. Use this method only in open areas.

 

4) Sighting along the arrows. In all cases except one, the arrow aligned with my compass after applying the megnetic declination. The one which didn't, pointed over the cliff. The others gave indicatiosn close to the first method.

 

Conclusion: the disk is most likely gone and a drill hole may be there, but I could not find it. I will report this to the NGS as Not Found with an explanation of what I found and what I did to searchg for the station.

 

I will official "Give up" on this one, but if anyone wants company for a try they would like to make, talk to me and I'll probably come along.

 

But The Benchmark Gods not only taketh away, but ocassionally they giveth.

 

I had my revenge an hour or so later. This:

 

(click on image for log)

Edited December 18, 2006 by Papa-Bear-NYC

[+Ernmark]

Congrats on the FOREST recovery ! ...looks like some serious elevation change getting down to that one!

[+m&h]

Fabulous log! Fun to read, fun to look at. Very impressive. Congratulations.

[mloser]

Dang! And I was invited along on this trip but a family engagement prevented me from going.