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Details for Benchmark: HV1841

N 38° 53.367 W 077° 02.100 (NAD 83)

Altitude: 36.02

Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)

Location:
In DISTRICT OF COLUMBIA county, DC View Original Datasheet
Designation:
A
Marker Type:
NGS Benchmark
Setting:
setting not listed - see description
Stability:
May hold, but of type commonly subject to surface motion.

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Definitely will have to arrange visit to this one!

[Photos:]
photoWashington Monument Benchmarks

Atlas Obscura has an entry on this benchmark:
http://www.atlasobscura.com/places/washington-mini-monument

The GPS in my Android phone read:

N 38:53.344
W 77:02.115

The GPS in my phone is not surveyor grade.

[Photos:]
photoView of the monument.

Found in good shape while exploring Washington DC with TaGeez

In DC for a conference and mapped out an ambitious agenda for finding virtual, earth, multis, puzzles and regular caches, as well as some bench marks!
Walked all around the monument!
TFTC< ponil

found while doing nearby virtuals

Recovered in good condition.

What a fascinating piece of history. I was able to spot the location based on this article: http://archives.profsurv.com/magazine/article.aspx?i=71196 and this video: https://www.youtube.com/watch?v=ioZIwoFT_LA

[Photos:]
photo22 Sep 14
photoHV1841

Based on what I could tell this is the cover to the benchmark, then again I could be as wrong as the rest. I was not about to hop the chains or try to lift the cover here.

[Photos:]
photoHV1841 Benchmark Cover
located in Washington, D.C.
photoHV1841 Benchmark Area
located in Washington, D.C.

Please read the note from DaveD...he is the Chief Geodetic Surveyor for the National Geodetic Survey. The datasheet from the NGS has photos of the mark. The September 2012 issue of Professional Surveyor Magazine includes a story about Benchmark A, or the mini-monument, and a photo. http://www.profsurv.com/magazine/article.aspx?i=71196

Found while on vacation

None of the posts listed below found station A (HV1841). Look at the pictures of the station on the NGS datasheet and you will get a better idea of where it is. You need National Park Service permission and assistance to remove the cover and see the actual mark - at NGS we call it the Mini Monument.

Used other photos to find this one.

[Photos:]
photoclose up view of benchmark
photoMr Sammydogs pointing to the benchmark

Eine interessante Variante von Geocaching, die ich so bisher noch nicht kannte. Und wenn man schon mal über den großen Teich gereist ist, muss man dies natürlich auch mal testen! Der Benchmark befindet sich wie angegeben in gutem Zustand am bekannten Ort!! Vielen Dank fürs Zeigen!!

[Photos:]
photoHV1841

We found the covers mentioned below...however we aren't convinced either is 'the one' so we are not claiming this as a find. The cover should be metal and 24 inch wide, we only found ones that met one of these criteria. We also found several sewer covers.

A walk around Washington Monument to find all the BMs.

[Photos:]
photoHV1841

Found this one today while walking around - sharing the monument area with thousands of my best friend here looking at the cherry blossoms! According to description, this mark is approx 120 feet south of the monument, so it's not the small circular covers around the base of the monument. Didn't attempt to open this manhole cover.. found as described. "Carson" inscribed on southern edge of cover. Cover is rectangular, with long dimension being the 24 inches described.

[Photos:]
photoBenchmark HV1841
photoBenchmark 1841 - Vicinity - looking North

I found the manhole which lies inside the chained grassy area. This is a full-sized manhole, not the small aluminum access lids located near the monument base. This is approximately 150' south from the base of the monument.

[Photos:]
photoA - Washington DC

Found while in D.C. with the family geocaching and vacationing!

Found it but did not attempt to open it.

N 38° 53.365 W 077° 02.122

Found this one while on a visit to the Washington Monument with my family. Got some interesting looks from passers by, but I am used to it.

[Photos:]
photoAccess Cover opened

Found the cover as noted. Talked with a park policeman who knows about all the benchmarks around the WM... Pointed me to this one.

Found it on a beautiful day in DC.

Found the cover and all the references are very good. Did not attempt to open cover - it looks really heavy and there are lots of park police around. I judged the mark to be better left unrecovered as inaccessible.

Documented History (by the NGS)

Unknown by DOD (MONUMENTED)
01/01/1971 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1971 AT WASHINGTON. AT WASHINGTON, D.C., 121.0 FEET SOUTH OF THE SOUTH FACE OF THE WASHINGTON MONUMENT, 28.0 FEET SOUTH OF THE SOUTH CONCRETE CURB OF THE CIRCLE DRIVE AROUND THE MONUMENT, 3 FEET SOUTH OF THE SOUTH FACE OF A 15- X 21-FOOT CONCRETE BOX WHICH PROJECTS 2 1/2 FEET ABOVE THE SURFACE OF THE GROUND AND WHICH HAS A METAL COVER, AND IS THE TOP OF AN OBELISK WHICH IS INSIDE A BRICK WELL WITH A 24-INCH METAL COVER.
01/01/1974 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1974 RECOVERED IN GOOD CONDITION.
01/01/1984 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1984 RECOVERED IN GOOD CONDITION.
05/13/1992 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1992 IN WASHINGTON, D.C., AT THE WASHINGTON MONUMENT, THE POINT LEVELED IS THE TOP OF AN OBELISK WHICH IS INSIDE A BRICK WELL, 36.9 M (121.1 FT) SOUTH OF THE SOUTH FACE OF THE MONUMENT, 8.5 M (27.9 FT) SOUTH OF THE SOUTH EDGE OF A CIRCLE DRIVEWAY, AND 0.9 M (3.0 FT) SOUTH OF THE SOUTH FACE OF A 15 BY 21-FOOT CONCRETE BOX THAT PROJECTS 18-INCHES ABOVE THE GROUND SURFACE. NOTE--ACCESS TO THE DATUM POINT IS THROUGH A 24-INCH METAL MANHOLE COVER.
06/15/1992 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1992 IN WASHINGTON, D.C., THE POINT LEVELED IS THE TOP OF AN OBELISK WHICH IS INSIDE A BRICK WELL, 36.9 M (121.1 FT) SOUTH OF THE SOUTH FACE OF THE WASHINGTON MONUMENT, 8.5 M (27.9 FT) SOUTH OF THE SOUTH CONCRETE CURB OF A CIRCLE DRIVE AROUND THE MONUMENT, 0.9 M (3.0 FT) SOUTH OF THE SOUTH FACE OF A 15- BY 21-FOOT CONCRETE BOX WHICH PROJECTS 0.8 M (2.6 FT) ABOVE THE SURFACE OF THE GROUND. NOTE--ACCESS TO THE OBELISK IS THROUGH A 24-INCH METAL COVER.
09/28/1998 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1998 (RLA) RECOVERED AS DESCRIBED.
11/22/1999 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1999 (RWA) RECOVERED AS DESCRIBED.

Control Text

  • The horizontal coordinates were scaled from a topographic map and have an estimated accuracy of +/- 6 seconds.
  • The orthometric height was determined by differential leveling and adjusted by the National Geodetic Survey in April 2000.
  • The geoid height was determined by GEOID99.
  • The dynamic height is computed by dividing the NAVD 88 geopotential number by the normal gravity value computed on the Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 degrees latitude (g = 980.6199 gals.).
  • The modeled gravity was interpolated from observed gravity values.

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