A really fun find

[Papa-Bear-NYC]

LX4165 "HOOK MT 2"

 

I wanted to share this experience since it brought to bear all the techniques we as amateurs sometimes need to find a mark which is not sitting there asking to be found. And what is more - I found it.

 

I first decided I had to recover this station when I found that log for BUTTERMILK, the oldest NGS mark in the US, which I recovered with Holtie a few months ago, had in the 1897 entry: "LINE WAS OPENED TO HOOK MT. 2". So I said, I gotta find that one, now that we've found this one.

 

This recovery made me happy to be a benchmark hunter. It involved climbing a mountain with a beautiful view, using every clue in the description including the use of two steel tapes to zero in on the mark, finding it 3-4 inches below the surface, and lastly finding all the reference marks and reference points. To make matters "more interesting", both Reference Marks had been cut off, and only the stems remained.

 

The entrance to the trail is off Route 9W about .4 miles north of Christian Herald Avenue. I had plotted out the bearing to the 1938 Azimuth Mark from the station using Google Maps and the azimuth line crossed the road very near the start of the trail. After one false start, I found it in plain site practcally acrross the road from the trail entrance (it's about 45 yards south on the opposite side of the road). This easy find was a good omen.

 

Azimuth mark near the start of the trail

 

The trail is relatively easy and I was at the top in about 20 minutes. I started by surveying the area and looked for every drill hole and spot on the bedrock to find the reference marks. They were both only stems. At last I found RM 2, which was a prominant shiny brass plug which was easy to find if you happened to look at it.

 

RM 2 was easy if you looked at the right spot

 

From this point I used tape and compass to the station mark area. Use of a metal detector turned up nothing. Undaunted, I measured out to RM 1 from the presumed area. In the meantime, several bird watchers showed up and we chatted as I measured and searched. Meanwhile I noticed a few drill holes which I would come back to later. I decided that RM 1 was near where one of the bird watches was, so I told him what I was looking for and he helped me scout around. One false lead was a depression filled with dirt which turned out to be just rock under the dirt. Finally I saw something right where he was standing, and close inspection showed it was the very faint remnant of the brass stem of RM 1. Now it was two down and closing fast!

 

RM 1 was much tougher to spot

 

The bird watchers wandered off and some hikers showed up. As I explained what I was doing to them, another pass of the metal detector turned up nothing so I took out my two steel tapes, held the ends down with rocks on the 2 RMs and triangulated the respective distances to the station. I found the spot, probed a bit and voilla! Paydirt! The hikers were not a little amazed that I could find the thing so easily - HA! There under 3-4 inches of hard packed dirt was the old USE disk placed 75 years ago. This was the first disk placed on the 1851 station. It's position was verified by measurements from 4 old drill holes.

 

Success 3-4 inches below ground

 

Those 4 drill holes now occupied me. I found the 3 from the 1992 report, and the 4th one which they had not reported. It turns out they are located at appoximatly the 4 cardinal directions from the mark, and the lines connecting the north/south and the east/west drill holes cross at the station. It all worked. If you find the drill holes, it may be easier using them than trying to measure from the RMs.

 

I thought it woukld be cute putting this collage together. Oops! Where is the Azimuth Mark?

 

If you recover this mark, be sure to bury it when you are done. It has only lasted as long as it has since it it out of sight and underground away from vandals and muggles.

[+Klemmer]

Another great recovery! Way to go!

[CallawayMT]

As always a well documented and interesting story.

 

Another job well done.

 

CallawayMT

[Difficult Run]

Nicely done Papa-Bear!

As always, a wonderful story to boot!

 

~ Mitch ~

[+Holtie22]

Great find Papa-Bear! So, could you see over to Buttermilk from up there?

[Papa-Bear-NYC]

Thanks to all.

 

As for BUTTERMILK, there wasn't much view in that direction. The best views were southeast across the Tappan Zee Bridge.

 

This one:

 

 

Now here's a question for the experts:

 

In 1932 the USE recovered and remarked the station with one of their disks (it's still there). Later that year, the CGS came in and "checked" what the USE had done. here's the log:

 

LX4165 STATION RECOVERY (1932)

LX4165

LX4165''RECOVERY NOTE BY COAST AND GEODETIC SURVEY 1932 (CAE)

LX4165''STATION WAS APPARENTLY RECOVERED. WITHIN YEAR, U.S. ENGINEERS

LX4165''HAD RELOCATED AND REMARKED THIS STATION WITH ONE OF THEIR OWN

LX4165''STANDARD DISKS, WHICH IS NOW IN PLACE.

LX4165''

LX4165''IN REOCCUPYING THIS STATION, AN INTENSIVE STUDY AND SEARCH

LX4165''WAS MADE FOR EVIDENCE BEARING ON POSITION OF STATION, AND OLD

LX4165''DRILL HOLES WERE RECOVERED. MEASUREMENTS CAREFULLY MADE WITH

LX4165''ARCS DRAWN LED TO CONCLUSION THAT IT HAD BEEN REMARKED BY

LX4165''U.S.E.D. AS ACCURATELY AS COULD BE DONE CONSIDERING TRIANGLES

LX4165''OF ERROR WHICH AROSE FROM THESE ARCS DRAWN. STATION WAS

LX4165''THEREFORE ACCEPTED AS RECOVERED.

 

Now my question is what do they mean by "ARCS DRAWN"? When I sighted along the drill holes, the two sets aligned with the station and the intersection of the lines made by the north & south holes and the east & west holes was at the station, (to within an inch or two - the best I could do without fancy-shmancy equipment).

 

So what's with "ARCS"? with the two lines only 25 - 30 feet long, aren't straight lines as good as you can get? Were they trying to construct great circles on the earth ellipsoid? That seems kind of overkill.

 

Anyone know what that log means?

[Bill93]

Only a guess, but I'm going to suggest that they relied more on distances from the RM's rather than intersecting the lines. So if you hold a tape on each RM and swing an arc across the region of the main station you get a set of slightly curved arcs that don't cross precisely in the same place. Any three of them make a triangle of uncertainty (with an indistinguishable bulge to the sides), where the smaller the triangle the better the agreement.

[Papa-Bear-NYC]

Only a guess, but I'm going to suggest that they relied more on distances from the RM's rather than intersecting the lines. So if you hold a tape on each RM and swing an arc across the region of the main station you get a set of slightly curved arcs that don't cross precisely in the same place. Any three of them make a triangle of uncertainty (with an indistinguishable bulge to the sides), where the smaller the triangle the better the agreement.

The problem with that interpretation is that prior to the 1932 CGS "Investigation", there were no RMs. They are the crew who set the RMS after they decided that the position was good. If you look at the datasheet, here is the complete log from 1932:

LX4165

LX4165 STATION RECOVERY (1932)

LX4165

LX4165''RECOVERY NOTE BY COAST AND GEODETIC SURVEY 1932 (CAE)

LX4165''STATION WAS APPARENTLY RECOVERED. WITHIN YEAR, U.S. ENGINEERS

LX4165''HAD RELOCATED AND REMARKED THIS STATION WITH ONE OF THEIR OWN

LX4165''STANDARD DISKS, WHICH IS NOW IN PLACE.

LX4165''

LX4165''IN REOCCUPYING THIS STATION, AN INTENSIVE STUDY AND SEARCH

LX4165''WAS MADE FOR EVIDENCE BEARING ON POSITION OF STATION, AND OLD

LX4165''DRILL HOLES WERE RECOVERED. MEASUREMENTS CAREFULLY MADE WITH

LX4165''ARCS DRAWN LED TO CONCLUSION THAT IT HAD BEEN REMARKED BY

LX4165''U.S.E.D. AS ACCURATELY AS COULD BE DONE CONSIDERING TRIANGLES

LX4165''OF ERROR WHICH AROSE FROM THESE ARCS DRAWN. STATION WAS

LX4165''THEREFORE ACCEPTED AS RECOVERED.

LX4165''

LX4165''TWO NEW REFERENCE MARKS WERE SET, BOTH STANDARD BRONZE DISKS

LX4165''STAMPED HOOK MT. 2.

LX4165

LX4165 STATION RECOVERY (1932)

LX4165

LX4165''RECOVERY NOTE BY US ENGINEERS 1932

LX4165''RECOVERED IN GOOD CONDITION.

LX4165

So it's back to the drill holes. But it's still a valid scenario, assuming the drill holes do not line up exactly, the sweeping of an arc from each of the 4 drill holes will give a set of overlapping triangles which presumably was where the station disk was found.

[mloser]

This seems to be one of those odd marks that had no useful data before they were "rediscovered" (maybe Dave Doyle can dig up some old paper trail for us though), and a couple of things come to mind.

 

The first is that your belief that the drill holes line up to cross the station is valid and a common occurance in older tri-stations. DAUPHIN is an old mark from 1883 whose monumentation states FOUR HOLES ARE DRILLED IN NEIGHBORING ROCK SO THAT LINES JOINING OPPOSITE ONES, INTERSECT OVER CENTER OF STATION. PORT CLINTON is similar: FOUR HOLES ARE DRILLED IN NEIGHBORING ROCKS, SO THAT LINES JOINING OPPOSITE ONES INTERSECT OVER CENTER OF BOLT, being only one word different. I have seen others like this and in fact would expect interesecting drill holes in any mark around my area that was set in the late 1880s whether they were mentioned or not.

 

The second is that Bill93 is also correct about the arcs, or at least it makes sense. If they 1932 party had access to the distances from the drill holes they could have swung arcs and recovered the station location.

[Papa-Bear-NYC]

This seems to be one of those odd marks that had no useful data before they were "rediscovered" (maybe Dave Doyle can dig up some old paper trail for us though), and a couple of things come to mind.

Actually I don't agree with this. This mark has a continuous history of recoveries since the 19th century and it's one of only a few First Order stations in the area. I think the 1932 crew was very interested in verifying the location of this mark since it would be needed as a basis of many of the triangulations that went on in that time frame. Most of the marks on both side of the Hudson were done in the 1930s and this is one of the few First Order stations, along with HIGH POINT now lost (but I'm still looking ), ALPINE, and of course BUTTERMILK.

 

Maybe Dave Doyle can relate how a First Order station was (or was not) important in that era.

 

But I think your analysis of the use of the drill holes and the "arcs" is probably right on the mark.

Edited May 18, 2007 by Papa-Bear-NYC

[+shorbird]

What a great story, and pictures! It's so satisfying, isn't it?