Top image: Monument at station "Prospect Park Water Tower," the origin of the borough of Brooklyn coordinates. Bottom image: Plaque commemorating station "Buttermilk."

Report of the New York and New Jersey Boundary Commission for Lands Lying Under Water…(1888)

Most surveyors work in coordinate systems and elevations of one kind or another, whether they are simply computing the closure of a deed on an assumed system or working in the newest HARN adjusted system of the 1983 State Plane Coordinate System. Coordinates and elevations are inescapable and indispensable.

I'd like to discuss the physical representations of these coordinates, namely monuments, and the origins of the systems they represent. Greater New York is one of the most interesting cities to survey. Whether on busy city sidewalks under steel covers or in quiet salt marshes along busy waterways, monuments silently and stoically hold their positions. "Oyster monuments" used in the 1800s to delineate underwater rights to oyster beds expressed as "townships,” state survey monuments along the Arthur Kill and Kill Von Kull, which were set but never located, State Boundary Commission monuments in the same area used to define the state boundary, Borough Topographic Bureau (or Borough President) monuments on street corners, Harborline Reference monuments along navigable waterways, and so many more they are too numerous to list.

In the greater New York City vicinity, there are, by my count, at least 13 coordinate systems and seven elevation datums all pre-dating the state plane coordinate systems and the national vertical datums. This does not include purely local "project systems" used in building bridges, tunnels and railroads, etc. Two reports are instrumental to understanding the New York City Borough systems. The Triangulation of Greater New York City From 1903 to 1908 as published by the Coast and Geodetic Survey (which I will discuss shortly) and Precise Leveling in New York City From 1909 to 1914 by Fredrick W. Koop, and published by the Board of Estimate and Apportionment. Koop was instrumental in the triangulation as an observer and computer and is truly to be commended for his historical insight in gathering information on the vertical datums in use in New York City. These two reports comprise the foundation of survey work in the city and are as valuable for their establishment of uniform systems as for their explanation of observation, computation and problem solving. Koop ran levels from Perth Amboy, N.J. to Dobbs Ferry, N.Y. setting 1,186 bench marks. He covered all five boroughs and was extremely careful in his work (one loop of 73 miles had a closing error of 0.013’). His work was considered accurate enough by the Coast and Geodetic survey to be held as fixed in the general adjustment of 1929. And I find no other way to describe the datums of New York City but to quote Mr. Koop verbatim with minor comments added.

In The Final Results, of the Triangulation of the, New York State Survey dated 1887, five origins are chosen to cover New York state. As well as establishing latitudes and longitudes, spheroidal coordinates were established for these systems, however, it was suggested that they be considered as plane coordinates for small local areas. The one covering the area of New York City, being upstate, is USC&G station “Helderberg (1876)” as adjusted by the state survey (N 875,326.86, E 1,997,122.11 N.Y.L.I.Z. ’27 COMPUTED). This station was chosen to cover the area between 73 degrees 15 minutes and 74 degrees 50 minutes west longitude. This station is based on an arc of triangulation of the U.S.C.&G., starting on the Hudson river near Albany and stretching across upstate New York state and tying into an arc of triangulation of the United States Lake Survey (as reported in The Final Report of the United States Lake Survey, 1882 and The Annual Report of the United States Coast and Geodetic Survey for 1884, Appendix 9).

In Manhattan, which is thick with origins, there is the Randel system, which John Randel Jr. established around 1810 to delineate the new city street grid from near 14th St. to 155th St. (origin unknown). The most important document in the early city’s development, A Map of the City of New York by the Commissioners Appointment by an Act of the Legislature Passed April 3, 1807 and commonly known as “The Randel Survey” or “The Commissioners’ Plan,” of 1811, the map establishes the familiar “grid iron” of most of Manhattan. This map, which measures 8’ 10” by 2’ 7”, shows not only the topography of the island, but also the proposed layout of the future city. It took Randel from May or June 1808 to the fall of 1810 to complete the survey of over 11,000 acres. Between 1811 and 1821, Randel set three-foot nine-inch white marble markers engraved with each street number at each intersection of the proposed street system. Where rock protruded, half-foot long bolts were set. Upon completion 1,549 monuments and 98 bolts were set. Randel then established elevations on some of these points. Randel also drafted a set of farm maps at a scale of 100 feet to an inch, in a series of 92 sheets, which if joined would measure 11’ by 50’. It is known that he derived his latitude and longitude system based on the city hall as an origin.

There is the Serrall system used to establish the streets from 155th St. north, which is an extension of the street grid (N 220,692.43, E 2,015,688.10 NYLIZ '27 C.). This system was used by the United States Engineers for harborlines north of 155th St. The computation of this origin, based on a map entitled The Port of New York Authority, Hudson River Bridge, Control Triangulation Systems dated April 1929, shows the southeast corner of Tenth Ave. as N 0.000 and East 0.000 feet. There is the old borough survey system, which covers lower Manhattan, and has an origin in the vicinity of 2nd Ave. and East 14th St., being north 20,000 and west 20,000 (origin unknown). There is also the borough topographic origin, as per the monument sheets issued by the topographic bureau (N 169,751.12, E 1,997,209.04 NYLIZ ’27 C). These sheets show the monuments and their coordinate values and cover lower and mid-Manhattan. Then there is also the borough traverse system, used to traverse between two established USC&G stations as shown on a map entitled Traverse Tie-In to Triangulation Stations of U.S. Coast and Geodetic Survey, Borough of Manhattan, New York City and dated June 1917 (N 162,595.13, E 2,002,422.34 NYLIZ. '27 C.).

And as for elevations, Koop, in “Precise Leveling in New York City,” explains The Public Works Datum of Manhattan. About 1790, John Randel Jr. established a bench mark on the southwest corner of the watertable (foundation stone) of a column at the old almshouse at Bellevue Hospital. Its elevation fixed at "20.558 feet above high water mark.” This location near 1st Ave. and 27th St. was chosen because Randall believed this would be near the center of the new city. Because this bench mark was difficult to access, a monument was set closer to 27th St. between the years 1830 and 1840 whose elevation was 17.797’. From this initial bench mark, several level lines were run to a large "T" cut on a stone just below the water table at the southwest corner of the New York City Hall. And by agreement between the city surveyors around 1840, its elevation was fixed at 24.143’ above the monument at Bellevue, or 42.210’. Until the year 1880 these two bench marks constituted the only "official" bench marks in Manhattan. In 1909 it was found that the "T" cut was nearly three inches lower than its accepted value. It is not known at what point along the shoreline or for how long Randel observed the tides to produce his elevation. This datum (the oldest known in New York) was adopted as "The Public Works Datum" or "The City Datum.” In 1817, as part of his contract to provide the street layout of the new city, Randel wrote on his "Farm Map" of 1819 that he established elevations on the monuments on 1st, 3rd, 5th, 8th, and 10th Avenues, "above a medium between high and low tide"; while a note on his "The Commissioners' Plan" of 1811 states "elevations above high water are shown as V.5, the Roman characters standing for feet and the Arabic for inches."

In 1880, Mr. A. G. Culver, assistant engineer for the Department of Public Works, ran levels from the original monument at Bellevue to Highbridge Tower, setting elevations five blocks apart and at every avenue intersecting these blocks between the Hudson and East Rivers. This datum was adopted by the Sewer, Water and Highway Departments of Manhattan; the Pennsylvania Railroad; the New York Central Railroad; and the Rapid Transit Railroad Commission. None of these monuments, to my knowledge, have survived the ravages of time and construction. The elevation of this datum until 1909 was thought to be 2.67’ above mean sea level, as described in The Proceedings of the Municipal Engineers of the City of New York 1905, the actual elevation of this datum is 2.750’ above mean sea level (NGVD 1929).

Also in Manhattan, there is the general topographic origin at Tenth Ave. extended and W. 225th St. (N 236,938.28; E 2,024,680.81 NYLIZ '27 published). This origin was used in the city’s attempt to perform a triangulation about 1900 and was later adopted for use in the west Bronx and Queens. Map entitled Map Showing the Progress of the Triangulation for the General Topographical Survey of the Five Boroughs of the City of New York dated December 31, 1900. This map is particularly interesting in that it shows that the triangulation is well along in The Bronx and Queens. It also depicts “the bound polygon of control” consisting of “High Bridge Tower” and “Memorial Church” in Manhattan, “Prospect Water Tower” in Brooklyn, “Dunton St” in Queens, and “Jackson” in The Bronx. It also shows two measured baselines in east Bronx, one of which reappears later in the “Triangulation of Greater New York.”

All of these Manhattan systems hold Tenth Avenue (or Amsterdam Ave.) for orientation, which is nearly 29 degrees east of true north. A map entitled Map Showing True Bearing of Amsterdam Avenue drawn by the Bureau of Engineering of the Manhattan Borough Presidents' office and dated September 1920, shows 10th Ave. as 29 degrees and 11.3 seconds east of true north as determined by observations on Polaris on July 17th, 1920. Through computation I found that the Manhattan traverse is rotated 28 degrees 59 minutes and 28 seconds east, while Serrall and the Queens systems are both rotated 28 degrees 58 minutes and 4 seconds east, which confirms that the Queens system is an extension of the Serrall system. For example, the Serrall coordinate for Memorial Church is S 17,384.49, E 5,254.69 and in the Queens system its coordinate is S 35,952.82, E 5,254.69; only the southing has changed 18,568.33 feet.

Also in Manhattan is the Memorial Church system, which was used by the United States Engineers (of the War Dept.), which has as an origin the northwest, and largest, of four minarets on the Memorial Church of the Beloved Disciple at 89th St. between Park Ave. and Madison Ave. (N 202,938.92, E 2,011,866.01 NYLIZ '27 P.). The U.S. Engineers adopted the Memorial Church grid to delineate Harborlines south of 155th St. And finally, there is the Dock Department system, which has an origin at 40 degrees, 45 minutes north latitude and 74 degrees west longitude (N 191,080.21, E 2,000,000.00 NYLIZ '27 C.). This information is contained on a map entitled Computation of Mosmans’ Three Origins Into Dock Dept. Co-Ordinates and Method of Converting Monuments and Stations in the Several Boroughs Into Dock Department System of Co-Ordinates dated July 1910. A.T. Mosman, the USC&G representative responsible for the report "The Triangulation of Greater New York City.”

As related in Precise Leveling in New York City, The Dock Department Datum was based on mean low water at Pier A at the battery. The initial elevation was determined by a short series of tidal observations made at this point, but in 1898 after 12 years of continuous observations, the datum was raised 0.24 foot and called the "New Battery Datum.” Prior to 1886 elevations were based on a large "T" cut in the south side of the east entrance to Castle Garden (the cut no longer exists), the elevation of which was 14.74 feet above mean low water and 47.09 below the "T" cut on the New York City Hall. The actual elevation of this datum is 2.103 feet below mean sea level (NGVD 1929). According to The Proceedings of the Municipal Engineers of the City of New York 1905, this datum was thought to be –2.09 feet.

When the city of New York was chartered in 1898 it grew from Manhattan Island to include the other four boroughs of Richmond (Staten Island), Kings (Brooklyn), the Bronx and Queens. The city at first tried to perform its own topographic survey based on its own triangulation. However, quickly realizing the scale of the problem, the Board of Estimate and Apportionment asked the United States Coast and Geodetic Survey to aid them in this triangulation. It was determined that Staten Island, Brooklyn and Queens would each receive a coordinate system and origin (with Brooklyn and Queens sharing the same system and origin). Manhattan was excluded having already established several systems. The Bronx was already well along in its triangulation of its western section, thanks to the city topographic bureau, but asked to be provided an origin and system in its eastern section.

As discussed in the published USC&G Report The Triangulation of Greater New York, by the Cooperation of the City of New York and the United States Coast and Geodetic Survey, Executed 1903-1908 this was the first area triangulation of a major city. The report established a primary triangulation and a secondary triangulation, comprising 968 computed triangles, 181 geographic stations and two baselines. The origin of the computations was station Fort Tompkins 2 (1868), and an azimuth to Sandy Hook Light House (1835), both of which still exist. (As an aside, the first triangulation of record on the North American continent was also executed in Greater New York in 1817 and the oldest surviving triangulation station Buttermilk (1833) exists just north of the city; the French having performed a triangulation in South America in the 1730s to determine the length of a degree.) Queens initially cooperated by providing manpower and station building but quickly disassociated itself from the survey and went its own way.

These grids are all computed on the North American Datum of 1913, previously known as the United States Standard Datum, so direct conversion of coordinates established in the report to the North American Datum of 1927 is subject to small errors.

A little basic information becomes necessary at this point. There are several coordinate system types. The report utilizes a "tangent plane" system. In this approach, only one point, generally the origin, is coincident with a spheroid (or ellipsoid) of reference (in contrast the State Plane Coordinate Systems intersect a cylinder along two parallels, as in a Lambert system, or two meridians, as in a Transverse Mercator system). These are very convenient for computational reasons. Scale and convergence are ignored and simple geometry is all that is necessary to compute positions. However, this is not to say there are no problems with such a system. Scale distortions are relatively small within 20 miles of the origin (about 1 part in 60,000 or 70,000) but quickly grow outside this radius. And although scale is exact on any line connecting a point with the origin, grid distances anywhere else between points will be longer than the measured distance. Elevation factors are also acceptably small in such a system (an elevation change of 500 feet is equal to about 1 part in 50,000).

In Richmond borough (or Staten Island), there is the Bogart system holding USC&G triangulation station Bogart (1885) as the origin with the coordinates N 0.000 and E 0.000, which at a later date was changed to south 20,250 and west 20,350; this monument though listed officially as destroyed, still exists in a small patch of woods on Todt hill (N 137,190.02, E 1,967,746.81 NYLIZ '27 P.). The U.S. Engineers use this system in the Upper New York Bay to delineate Harborlines. Distances in this system are on average 1 in 30,000 too small and the orientation is rotated about 5’ west. The borough used to issue topographic sheets from the early 1900s showing the complete topography, traverse lines and spot elevations, as well as references to the original field books. Also issued were computation sheets, showing the traverse lines between triangulation stations, monument designations and coordinates. Due to the nature of the topography of the sparsely settled island at the time, the monuments are random and often in or near the street lines.

As explained in Precise Leveling in New York City, The Richmond High Water Datum was referenced to a spike driven into the outlet of the Water street sewer at Stapleton, about 1890-1891, and considered "approximate high water" by W.S. Bacot, engineer of county roads. This datum was generally used in the county road system, though assumed datums were common. The levels on the Northfield town roads were connected with the Coast Survey bench mark at the foot of Morningstar Road, Elm Park. In 1899, John T. Featherston of the Richmond Sewer Bureau ran a series of levels from this bench mark, holding 13.152’. This value was provided by the Department of Docks and Ferries, and was obtained by adding 2.186’ to the coast survey datum, thus referring the elevation to the Dock Department Datum. In 1900, the Board of Public Improvements of New York City made a survey of the Arietta Watershed, using the County Roads bench marks on Arietta Street and John T. Featherston's bench mark #9 at Tompkinsville. The difference was found to be 5.309’ between these and in May 1900, all the bench marks were referred to high water by subtracting that amount. The bench marks established by the Richmond Topographical Bureau have since all been referred to bench mark #12 at Clifton, as corrected, and held at 9.586’ above high water, and as near as can be determined is coincident with elevations as established in 1890-1891. A series of tidal observations by the Department of Docks from 1908 through 1913 show this datum to be 0.803 foot higher than mean high water, at South Street in St. George. The Richmond Topographical Bureau uses this datum. The elevation of this datum as published in the Proceedings of the Municipal Engineers of the City of New York 1905 was thought to be +3.15’, the actual elevation of this datum is 3.192’ above mean sea level (NGVD 1929).

In the Bronx, in addition to the West Bronx system, there is the East Bronx system, utilizing USC&G triangulation station Parkway (1903-1908), with a value of N 0.000 and E 0.000 later revalued as North 28,000 and West 31,000. This monument was reported lost, then reported found, and then reported lost again, but may still exist (N 230,329.96, E 2,039,669.94 NYLIZ '27 P.). In this system once again, the scale factor is about 1 in 30,000 and the rotation again about 5” west.

According to Precise Leveling in New York City, The Bronx Borough Datum was referenced to a horizontal arrow marked "10 feet above mean high water" cut in the southeastern face of the north abutment of the old Third Avenue Bridge over the Harlem River. This bench mark was established from a bench mark of the Public Works Datum on the Harlem side of the same bridge whose elevation was 11.085’. From the "Arrow Bench" a cross was established at the entrance to the old Town Hall of Morrisania at 160th St. and 3rd Ave. The elevation was fixed at 25.935’ above mean sea level. The bridge and the town hall are both gone. In 1901 a complete system of levels radiating from the Town Hall and consisting of closed loops established bench marks throughout The Bronx. This datum, subject to random error, is identical to the Public Works Datum. The Commissioners of the Town of Morrisania, the Park Department and the Department of Street Improvements adopted this datum. The elevation of this datum, as reported in the Proceedings of the Municipal Engineers of the City of New York 1905 was +2.67’. The actual elevation of this datum is 2.608’ above mean sea level (NGVD 1929).

And in Brooklyn, USC&G triangulation station Prospect Park Water Tower (1903-1908) is the origin with coordinates of north 0.000 and east 0.000, and although the water tower itself is long gone, borough officials diligently prepared for the towers destruction and were able to place a monument which still sits quietly exposed behind a baseball homeplate in Prospect Park (N 162,779.32, E 2,008,942.41 NYLIZ '27 P.). Only Brooklyn retained its origin value as chosen in the report. Distances in this grid are about 1 in 25,000 shorter and the rotation is about 6” west.

As related in Precise Leveling in New York City, The Brooklyn Highway Datum was determined by J.S. Stoddard, a surveyor associated with John Randel Jr., who was hired to lay out the street system and the monuments necessary to delineate the intersections. He established elevations on 827 of these monuments relative to "the highest tidewater mark.” George Ingraham, extended a series of levels in Bay Ridge based on the monument on the northwest corner of 58th St. and 7th Ave. IN 1891, the Bureau of Highways used a bench mark on the Wallabout Bridge, based on the benchmark at Dry Dock number one in the Navy yard. It was soon discovered this elevation was in error and elevations were then referred directly to the bench mark at the Navy yard. About 1905, the Bureau of Highways ran a new series of levels from the monument at 58th St. and 7th Ave. throughout the borough. These elevations are based on Stoddards' determination of 98.48’ above high water. This datum was adopted by the Bureau of Highways and the Brooklyn Topographic Bureau, and was extended, with some random errors, to Flatbush, Flatlands, Gravesend, New Utrecht, New Lots and Bath Beach. The elevation of this datum was thought to be +2.80’ as reported by the Proceedings of the Municipal Engineers of the City of New York 1905. The actual elevation of this datum is 2.547’ above mean sea level (NGVD 1929).

And finally, the most interesting system, namely "The Queens Topographic" or "Queens Borough President" or "The Tenth Avenue" system. Queens chose to adopt the city topographic origin, which was at the southeast corner of Amsterdam Ave. prolonged and W. 225th St. It selected N 0.000, E 0.000 as the value of this point placing the entire borough in the southeast quadrant, making coordinates negative northings (or southings) and positive eastings. Manhattan was in the northwest quadrant as was the Bronx, and Staten Island revalued its origin to place itself in the southwest quadrant. Only Brooklyn retained its unique arrangement of a central origin and coordinates in all four quadrants.

Having selected its origin, it oriented its coordinates to Amsterdam (or Tenth) Avenue, which the borough holds as 28 degrees 59 minutes and 13.5 seconds east of the meridian of this point. The origin is based on an extension of one of Manhattan’s coordinate systems, namely, the Serrel (or Serrell or Serrall) system. This origin is on the east side of Amsterdam (or Tenth) Ave. at the south side of W. 155th St. This point is coincident with the East House Line of Amsterdam Ave. and the South House Line of W. 155th St. Holding this point and extending it through a similar point at W. 175th St., a distance of 18,568.333 ft., it was intended to arrive coincident with the city topographic origin. However, Tenth Ave. is unfortunately not a straight line, and the deviation caused an error of 4.20 feet to the east at the origin. When projected in the reverse direction, the line enters the South House Line of W. 155th St. by 2.64 feet and the East House Line of Tenth Ave. by 6.35 feet. Therefore, extending the Serrel origin to the actual origin (rather than the intended origin), one derives 18565.69 feet. The borough issues monument sheets showing the geometry of the blocks and the designated number of the monuments, which are often placed on every other block at a constant offset from the property lines, and as such are usable. However, knowing the monument’s number, one can go to the topographic bureau and find the monument’s coordinate (or rather a list of its changing coordinate values, the last being the most current) in a card file.

This origin information comes by way of a map entitled Relationship of the Origin of the Queens Coordinate System, the S.E. Corner of 155th St. and (10th) Amsterdam Ave. and USC&G Station Prospect Water Tower drawn by M.E. Milone, asst. engineer of the Topographical Section of the Dept. of Public Works, N.Y. city and dated March 1942, as copied by C.T. Chatfield A.E. of the Queens Borough Topographic Bureau.

As told in Precise Leveling in New York City, The Queens Borough Datum originated from a bench mark established on the old almshouse on Blackwells Island (Roosevelt Island), referred to mean sea level as established by a commission to lay out the streets of Long Island City, formerly a part of Newtown. From this bench mark, level lines were run throughout Long Island City and one in particular was established at Scwalenberg's Hotel at Borden Ave. and Vernon Ave. In July 1900, W.S. Dalyrimple, assistant engineer of the Queens Borough Topographic Bureau ran a series of levels over the entire borough. The origin used was the United States Coast and Geodetic bench mark "B" established in 1887 on Millers Hotel at Borden Ave. and Front St. The elevation was accepted as 5.770 feet above mean high water (in 1909 this mark was found to have settled 0.06 foot). In October 1902, the datum was modified by Ernest Ankener, Assistant Engineer, to agree with that of Long Island City. Using the old benchmark at Schwalenberg's Hotel as the new initial elevation, 0.578 foot was subtracted from all previously determined elevations, accepting 10.970 as the initial elevation. The actual elevation of this datum is 2.725 above mean sea level (NGVD 1929), as opposed to the published elevation of +2.75’, as given in the Proceedings of the Municipal Engineers of the City of New York 1905.

And the final datum, and the most interesting, as explained in Precise Leveling in New York City, is The United States Navy Yard Datum as referenced to a square cut in the top coping at the southwest corner of dry dock number one, in the Brooklyn Navy Yard, as established in 1850 (and still exists, and as far as I know, is the oldest bench mark in New York City). The elevation of this mark was determined as five feet above mean high water, the sill of the dry dock being 26 feet below mean sea level, as determined by tidal observations made about 1840. A series of tidal observations made at the yard by the Bureau of Yards and Docks from June 1902 to June 1903 show the mark to be only 4.43 feet above mean high water ±0.2 foot due to the short duration of the series. Between 1850 and 1860, the Division of Water Supply of the City of Brooklyn ran a series of levels holding 4.997 feet as the accepted elevation. The Brooklyn Sewer Bureau established a series of its own levels holding 4.999 as the fixed elevation of the mark. The Brooklyn Highway Department considers this mark as 4.167 feet. The Board of Estimate and Apportionment found 6.677 feet in its determination of the elevation and the Board of Water Supply found 6.762 feet according to its levels. No less than seven elevations have been determined for this one single bench mark! The actual elevation of this benchmark is 6.677 feet above mean sea level, thus giving the datum of 1.177 above mean sea level (NGVD 1929), as opposed to the elevation of +1.72’ as given in the Proceedings of the Municipal Engineers of the City of New York 1905.

And finally, the Administrative Code of the City of New York recognizes as the legal boundaries of Manhattan the Harborlines of the U.S. Engineers. The boundaries of The Bronx also include reference to coordinates of the “Parkway system.” Brooklyn similarly is defined by the “Prospect Water Tower” system of coordinates. And finally, in Queens, reference is made “to a certain large Pepperidge tree whose coordinates, based on the Tenth Ave. system, are south 62,552.329 and east 85,574.915 feet” being a corner in the borough boundary.