Academic journal article The Geographical Review

Re-Creating the Historical Topography of Manhattan Island*

Academic journal article The Geographical Review

Re-Creating the Historical Topography of Manhattan Island*

Article excerpt

During the nineteenth century the Island of Manhattan was transformed into a physical representation, or "material replication," of the Cartesian coordinate system through development of the grid street plan. The original grid plan, the Commissioners' Plan of 1811, consisted principally of a rectilinear matrix of 12 major avenues and 155 cross streets (Randel 1811). (1) All streets and avenues were numbered in consecutive order, thereby announcing to the world that the Manhattan landscape--with its hills, wetlands, streams, farmlands, and estates--was to be converted into a life-size Cartesian coordinate system. (2)

Before the plan was implemented, the Common Council hired John Randel Jr. to survey Manhattan Island. (3) The most detailed cartographic products of his surveys, the Randel Farm Maps (Randel 1819-1820), are currently held at the Manhattan Borough President's Office, and Randel's Field Books can be found at the New-York Historical Society (Randel 1812-1822). The Randel Farm Maps offer a unique snapshot of various socioenvironmental characteristics of the Manhattan landscape before the "armies of street openers" (Smith 1938, 127) leveled much of the island to make way for the grid. These maps depict the pre-grid landscape circa 1819 as well as the then-imaginary streets and avenues of the proposed grid plan. The surveying process that led to the production of the Randel Farm Maps was an integral component of the project to rationalize the landscape, so it is ironic that the same quantitative techniques that facilitated the "obliteration" of the pre-grid landscape offer the means by which to construct a three-dimensional digital model of pre-grid Manhattan topography.

RANDEL'S ELEVATION DATA

As a master's student in the Department of Geography at Pennsylvania State University during the fall of 2000, I became interested in the environmental history of New York City. Existing environmental histories of the city tend to focus on Central Park, water and sewer systems, and public health, but the development of the grid street system, which dramatically transformed the landscape and provided the spatial framework within which future environmental change would occur, was central to Manhattan's environmental history during the modern period. The literature on the Manhattan grid includes Paul Cohen's article, "'Civic Folly': The Man Who Measured Manhattan" (1988), and Paul Cohen and Robert Augustyn's book, Manhattan in Maps, 1527-1995 (1997). (4) From these sources I first learned of John Randel's forty survey field books and the Randel Farm Maps (Randel 1812-1822, 1819-1820).

A first look at the original versions of the Randel Farm Maps revealed that amid the profusion of cartographic information were pre-grid elevation values (in feet above a specified datum) at many of the then-imaginary intersections of the streets and avenues of the grid plan between 1st and 155th Streets. Cohen and Augustyn quote Randel as having stated that the Farm Maps included "the elevation of all monumental stones placed on the 1st, 3rd, 5th, 8th, and 10th avenues, above a medium between high and low tide water" (1997, 110). Although Cohen and Augustyn made note of this fact, no one-to my knowledge-had ever taken the time to convert this geospatial data set into digital format using geographic information systems (GIS) technology. I realized that by creating a point coverage of Randel's pre-grid elevation data using the Arcview GIS software package, it would be possible to make contours from the original data set and even create a three-dimensional surface model of Manhattan's pre-grid topography.

COMPILING THE DATA AND DETERMINING THE DATUM

During the summer of 2001 I compiled Randel's pre-grid elevation data, along with other cartographic information, from the Randel Farm Maps. In addition, I compiled a more limited elevation data set from the 1811 map of the Commissioners' Plan for comparative purposes. …

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