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trmcconn

Anchor Stubs

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Last week on a business trip to Long Island I had a free afternoon so (what else?) I went benchmark hunting. Turns out there is a little plot of undeveloped land smack in the middle of densely populated Nassau county, and that this little plot of undeveloped land (90 acres or so) just so happens to have a triangulation station smack in the middle of it: BETH-KU2634.  The land is owned by Nassau county and rented by a nice couple who operate a small truck farm there. They kindly gave me permission to visit the site.  

 

The data sheet says the station monument projects 2 inches but I had to dig down through about 2 inches of accumulated leaf litter to find it. One unusual feature of the site is worth mentioning: The station monument sits in the center of a roughly 10 meter square whose corners are marked by embedded chunks of metal that stick up about 6 inches out of the leaf litter. They resemble enlarged versions of the kind of angle irons you find in hardware stores for bracing corners of windows. They are very firmly embedded in the ground, sharp edged, and could inflict a nasty cut on an unwary passerby. The data sheet describes these as' "anchor stubs" and lists precise distances from each oneto the station mark as a kind of supplement to the reference marks. (I didn't find those, alas, but they're undoubtedly still there, buried under the same leaf litter that blankets the whole hilltop.) 

 

My guess is that these are remnants of the light platforms built when Beth was monumented. If so, I wonder why these were left in place, or, conversely, why you don't find them more frequently at other sites - these were the first I've seen.

 

(Tried to upload a jpg under 2 meg but it keeps refusing to upload - no idea why )

 

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Interesting.  It would indeed make sense for those stubs to be left from some tower. 

 

However, I doubt it was the triangulation crew's tower.  In 1951 when this mark was set, US C&GS was using Bilby towers, which were a triangular inner tower for the instrument and a triangular outer tower for the crews.  A single square tower is something else.  And it doesn't seem right that any triangulation tower would have been built so far off center from the disk, since the instrument had to be over the disk.  The stubs aren't mentioned until the 3rd entry on the data sheet, 1966, so I'm guessing there was a tower for some other purpose there sometime between 1951 and 1966. 

 

The data sheet says the leg distances are:

KU2634'THE STATION MARK IS A STANDARD DISK STAMPED BETH 1951 SET IN THE
KU2634'TOP OF A 12-INCH SQUARE CONCRETE MONUMENT PROJECTING 1 INCH ABOVE
KU2634'THE GROUND.  IT IS 11.2 FEET NORTHEAST OF THE SOUTHWEST ANGLE IRON
KU2634'ANCHOR STUB, 10.6 FEET NORTH-NORTHWEST OF THE SOUTHEAST ANCHOR
KU2634'STUB, 8.3 FEET SOUTHEAST OF THE NORTHWEST ANCHOR STUB, 6.9 FEET
KU2634'WEST-SOUTHWEST OF THE NORTHEAST ANCHOR STUB,

I don't think 10 meters is right.  From the data sheet distances, the side of the almost-square is about 12.8 ft (3.9 meters) and the mark is 2.48 ft from center.

 

Your pictures can be linked from your geocaching recovery report for KU2634, as this one of a stub

e52cc89d-a9fb-4917-b486-8d3280630efe.jpg

 

Edited by Bill93

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Thanks, Bill93. Yes, put the wrong units on the size estimate. It was also odd that the RM measurements were off. Maybe the original crew measured slope distance rather than horizontal. Aren't the RM measurements usually horizontal? Or do I have it backwards?

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Fire Observation Tower?

Edited by Z15

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The measurements are supposed to be horizontal. 

 

The fact that the re-measurement found them shorter would be consistent with the first numbers being slope distance with modest changes in elevation (1.72 and 1.42 m).  6.5 cm in 22.78 m sounds like too much to be due to inadequate tension on a sagging tape, which if the difference were smaller would be another likely problem.  But I'd have expected a C&GS crew to avoid both those problems.

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