Manhattan: Bolted at the Edge of the Grid

I like to look at history underfoot, though this bit of history is 5½ inches above my feet.

The history here is not only precisely 5½ inches above the sidewalk, its elevation is precisely 148.729 feet above sea level, and the historical object has been in place since the 1880s when Alston Culver put it there.

Here’s a closer look at what I’m talking about it.

See it? Not really? No worries – let’s set the scene.

The location where I’m standing is on 155^th Street, a significant street in New York City history. In the early 1800s, a Commission was formed to plan the growth of the city, and that plan turned out to be a grid of streets and avenues that reached as far as where I am standing at 155^th Street.

After City Surveyor John Randel, Jr. marked the grid on paper in 1811, his next step was to mark the grid on land by placing marble markers at proposed intersections. When markers couldn’t be placed because of bedrock outcrops, he set bolts in the bedrock. He placed a marker at the intersection where I am standing, but it was across the street from my location, and the marker doesn’t exist anymore.

Instead, what does exist is this galvanized iron bolt protruding from the column base.

The red arrow points to the bolt.

The bolt is not a bench mark set by Randel in the early 1800s, but, rather, one set by Alston Culver decades later in the 1880s.

Quite a bit happened in the area between 1811 when the City planned the grid and 1880. One significant change is that the countryside estates and farms around 155^th Street were sold off.

One large parcel of land was sold by a box-maker turned land-speculator, named Richard Carman, to Trinity Church in the 1840s, and the church made a large cemetery on the land. The north side of the Trinity Cemetery runs along 155^th Street and a stone wall marks the boundary. On the corners of the wall are ornamental columns, and on the base of the column on the corner of 155^th and Amsterdam Avenue is a bolt placed there by Alston Culver.

But why? Why was this bolt set here and who was Alston Culver?

Culver lived in Harlem, was involved with Tammany Hall politics, and was the Assistant Engineer for the Department of Public Works. Part of his job was to measure the elevations of Manhattan from Bellevue Hospital downtown all the way to High Bridge Water Tower uptown. To do that, he set markers, called bench marks, at intersections like John Randel, Jr. did years before him. The bench marks were then measured against a set mark to determine the elevation at each location. One of those bench marks is the bolt on 155^th Street, on the northeast corner of Trinity Cemetery.

Culver later took a job as Water Purveyor in the city, and he was noticed. The New York Press wrote, “Water Purveyor Alston G. Culver can be seen any day driving the avenue in his buggy on his way to inspect the work under his command.” He then ran, unsuccessfully, for state public office.

A few years later, his name hit the papers outside of New York City in connection with a mysterious death after Roy Culver, Alston’s younger half-brother, was fished out a river upstate. Even though he was found in the river with a weight tied to him, the coroner found no water in the victim’s lungs. There was, however, poison in his stomach. Alston thought his brother was murdered. A clue in the case was a letter signed by “A Stranger” who claimed that he killed Roy, who was obsessed with researching genealogy to prove his right to an inheritance. It seems that a Culver ancestor was an early settler of Long Island and Roy thought he might have a stake in the estate. As far as I can tell, the “Stranger” was deemed to be Roy himself, the mysterious death was officially assumed to be suicide, and there was no long-lost inheritance to be had.

Alston Culver changed jobs within the City and worked for the Finance Department, and he largely disappears from the public eye. 

Meanwhile, the city kept expanding, and 155^th Street was finally graded. Eventually the city grew all the way to 220^th Street at the upper tip of Manhattan.

As the city grew, a young man named Frederick Koop graduated from Cooper Union as a civil engineer, passed the civil service exam for assistant draughtsman with a respectable score of 92%, and was hired by the City. He shows up in the papers with a bit of mystery too. His roommate accused him of stealing $30, but when the police nabbed Koop that same day, Koop denied the charges, didn’t have the money on him, and said he simply was out having breakfast.

Koop, like Culver, worked on measuring the elevations of the City. By this time, in the early 1900s, however, the City was more than just Manhattan. In 1898, all five boroughs of Manhattan, Bronx, Queens, Brooklyn, and Staten Island consolidated into one City of Greater New York. Koop, promoted to Assistant Engineer, set out to measure them all.

To do so, Koop set 1,186 bench marks throughout the five boroughs and also gathered the data from existing bench marks set by others in the past, including the bolt on 155^th Street.

In this 1910 photo, you can see the ornamental column to the right of the intersection. This is how the place looked when Koop worked on his measuring project.

Photo by Thaddeus Wilkerson,1910, from the Collections of the Museum of the City of New York.

Over the years, the City used several different sites to measure elevation against. These sites are called datums, and Koop documented all of them, but only one was decided to be the official datum from that point forward. It's called, appropriately, the Standard Datum, and it's defined as the mean sea level at Sandy Hook, New Jersey. The bolt on 155th Street is, therefore, 148.729 feet above the mean sea level at Sandy Hook.  

Koop published his findings, listing all the bench marks in New York City and their elevations, in a publication called Precise Leveling of New York City in 1914. He went on the lecture circuit with it, at least a circuit of fellow engineers, and even illustrated his talks with lantern slides.

The bench marks that still exist are still used as measuring devices throughout the city. They mark history hidden in plain sight, not quite underfoot, but just above it.

Sources.