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Details for Benchmark: KU1297

N 40° 40.333 W 073° 58.033 (NAD 83)

Altitude: 179.77

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

Location:
In KINGS county, NY View Original Datasheet
Designation:
22
Marker Type:
bench mark disk
Setting:
set into the top of a round concrete monument
Stability:
May hold, but of type commonly subject to surface motion.

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Found it even though it is now covered by some plants and bushes.

[Photos:]
photoBolt

Found easily and in good condition. The original water tower was a benchmark called "Prospect Water Tower" that was part of the 1903 USGS Survey of New York City. As I understand it, the current mark was created when the water tower was demolished by dropping a plumb bob from the center of the tower tank to the ground. In any event, Papa-Bear's description is very accurate. Of note is that, just past the top of the stairs, there is a granite monument bearing the inscription "M.H. 2 Ft." with an arrow. There is nothing that's two feet from the marker, and I have no idea what M.H. represents. If this is a reference marker, it's not in any of the locations of the 1903 reference markers, all of which are long gone. I have posted a photo of this second marker, if anyone can shed light on its meaning.

[Photos:]
photo22 Copper Bolt
photo22 Monument
photo22 Setting
photo22 Second Marker
photo22 Park Entrance

Found as described in good condition.

This is an interesting situation. This station is a vertical control station (bench mark) which was surveyed to use the same monument as a triangulation station ([url=http://www.geocaching.com/mark/details.aspx?Pid=KU3532]KU3532[/url], "Prospect Water Tower").

That station has a long and interesting history and I reccomend you read the datasheet and log entries for it. In short, the old water tower (now gone) served as the origin of the Brooklyn coordinate system which defined street locations for the entire borough and it also served as one of the primary triangulation stations for the 1903 triangulation of New York City.

This station "22", as far as I can tell, was surveyed in 1952, long after the tower was gone, and uses the monument that marks the exact tower location.

To find it, go past the Library on Eastern Parkway and enter Mount Prospect Park (not to be confused with Prospect Park) and when you get to the top of the stairs, look for the granite hexagonal monument off to the right, just past the end of a chain link fence. See the photos.

[This entry was edited by Papa-Bear-NYC on Friday, February 17, 2006 at 2:04:08 PM.]

[Photos:]
photoKU1297 "22", Eastern Parkway, Brooklyn NY
View of the entrance to Mount Prospect Park, just past the Library. Go up the stairs, and the monument will be off to the right, behind the end of a chain link fence.
photoKU1297 "22", Eastern Parkway, Brooklyn NY
View of the granite monument from the top of the stairs. Note the chain link fence which ends just to the left of the monument (seen edge-on in this view).
photoKU1297 "22", Eastern Parkway, Brooklyn NY
The granite monument with the copper bolt. The bench mark is defined as the top surface of the bolt.

Enter the park via the gate and stairs at the westernmost end of the park, just east of the Public Library. When you get to the top of the stairs, you'll see the big hexagonal post protruding a few inches above the ground just ahead and to the right of you a few yards away. I wonder whether this (KU1297) is the same object that's described in the separate entry for KU3532? The description for KU3532 is not as detailed, but it seems to be the same thing, and I didn't find any other object matching the description of KU3532 anywhere in the vicinity. So I'm logging KU3532 as a find too.

[This entry was edited by LeoGeo on Tuesday, July 12, 2005 at 8:22:22 AM.]

Documented History (by the NGS)

Unknown by CGS (MONUMENTED)
01/01/1952 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1952 AT NEW YORK. AT NEW YORK, IN BOROUGH OF BROOKLYN, JUST SOUTH OF EASTERN PARKWAY ABOUT 0.1 MILE EAST OF GRAND ARMY PLAZA, ABOUT 109 FEET SOUTH OF SOUTH CURB OF EASTERN PARKWAY, ABOUT 67 FEET SOUTHEAST OF SOUTHEAST CORNER OF EAST WING OF BROOKLYN PUBLIC LIBRARY, 40 FEET EAST OF A LIMESTONE RETAININ WALL, 29 FEET WEST OF CENTER LINE OF CONCRETE STEPS LEADING NORTH TO EASTERN PARKWAY SIDE WALK, 9 FEET WEST OF CENTER OF A GATE IN PARK FENCE, 2.8 FEET NORTHWEST OF A CORNER IN PARK FENCE ABOUT 35 FEET ABOVE LEVEL OF EASTERN PARKWAY, AND IN THE TOP OF A GRANITE POST PROJECTING 10 INCHES. NOTE-- POINT LEVELED TO IS A 1-INCH BRASS PLUG IN CENTER OF 10-INCH DISK.

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 June 1991.
  • 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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