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Details for Benchmark: KU1276

N 40° 35.200 W 073° 57.933 (NAD 83)

Altitude: 10.49

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

Location:
In KINGS county, NY View Original Datasheet
Designation:
217
Marker Type:
chiseled square
Setting:
light structures
Stability:
Mark of questionable or unknown stability.

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Found in good condition, right above mark 216 (KU1277). Neat to get two marks together, and both are a cool part of NYC topographic history.

[Photos:]
photo217 Chiseled Square
photo217 Setting
photo216 and 217

There were two bench marks set on the old 5 story building of Coney Island Hospital at the corner of Avenue Z and Ocean Parkway. The building was completed in 1908 and the marks were set at the "northwest corner of the building", probably in 1909. Unknown to me (until I Googled the place), after the marks were set, they built a two story extension to the old building to the north with matching yellow bricks. So the old corner is no longer the corner. But it's OK, the marks are there and easy to find once you realize what's going on.

These marks were part of the first city-wide survey done with consistant datums after the consolidation of the city. The work was done from 1909 - 1913 amd the 1914 report [i]Precise Leveling in New York City[/i] by Frederick W. Koop is available in the NY Public Library. The marks in Brooklyn were numbered 178 (at Fort Hamilton) to 504 (at Newtown Creek). Some like these, are in the NGS database, but many are not and a number of these old marks are still around. Today I also recoverd #220 (see [url=http://www.geocaching.com/mark/details.aspx?Pid=KU1279]KU1279[/url]) and also #215, a non-NGS mark (see [url=http://www.geocaching.com/mark/details.aspx?Pid=KU1278]KU1278[/url], a nearby NGS mark across the street from #215).

The two marks consist of a chiseled square on the water table, and a 2 inch brass disk mount about 18 inches below. This survey often set marks in pairs - one for easy use by surveyors (the square) and one for very accurate leveling (the disk). The disk is a rarity. It's the only disk I know of made by New York City and there are probably less than 20 of them still in existance.

The chiseled square is on the corner of the limestone corner block of the brick water table at what used to be the northwest corner of the building.

[Photos:]
photoKU1276 "217" setting, Coney Island Hospital, NY
The north end of the old Coney Island Hospital building showing the 2 story extension, and the 5 story old section on the right. The 2 marks are at the corner of the old section of the building.
photoKU1276 "217" setting, Coney Island Hospital, NY
The corner of the old section of the building showing the two marks.
photoKU1276 "217", Coney Island Hospital, NY

Documented History (by the NGS)

Unknown by NYBE+A (MONUMENTED)
01/01/1952 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1952 AT NEW YORK. AT NEW YORK, IN BOROUGH OF BROOKLYN, IN SOUTHEAST QUARTER OF INTERSECTION OF AVENUE Z AND OCEAN PARKWAY, IN TOP OF LIMESTONE CAPSTONE OF BRICK WATER TABLE ON WEST SIDE OF CONEY ISLAND HOSPITAL BUILDING, 40 1/2 FEET SOUTH OF NORTHWEST CORNER OF BUILDING AND 2 FEET ABOVE GROUND.
01/01/1989 by USPSQD (GOOD)
RECOVERY NOTE BY US POWER SQUADRON 1989 (JD) RECOVERED IN GOOD CONDITION.

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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