By the spring of 1767, Ratzer had completed enough of his survey to have a small map of Manhattan—roughly equivalent to the area depicted on the Montresor Plan—engraved, and it was offered for sale in the New York Gazette on August 21, 1769.

Today, this smaller map is known as the “Ratzen” Plan due to an error made by the engraver. In its upper left corner, it sports a dedication to “Sir Henry Moore, Baronet, Captain General and Governor in Chief” of New York, which makes it probable that Moore commissioned the map, though we don’t know that for certain. We also don’t know if Moore wanted a second map for military or commercial purposes, though it would ultimately be used for both.

What we do know is that while the Ratzen Plan bears a strong similarity to the Montresor Plan, even a cursory examination shows where Ratzer improved upon his predecessor’s work.

For one, almost every street on the Ratzen Plan is named, where only a handful of roads on Montresor’s survey are given any designation. Also, while both maps include the Collect Pond (labeled “Fresh Water”) behind the Commons, Ratzer’s survey shows what seem to be accurate boundaries; Montresor’s is much more likely just a rough approximation of where the pond lay. Even though Ratzer’s survey must have followed directly on the heels of Montresor’s, he includes full-fledged roads (such as Mott and Mulberry) that Montresor only hints exist. Similarly, Division Street, which created the boundary between the properties of James Delancey and Henry Rutgers, is absent from Montresor and appears on the Ratzen Plan.

Another anomaly: Nearby, Montresor runs the “Road to Crown Point” east from the Bowery to the property of T. Jones. Ratzer designates that street Grand—as it’s still known today—but has it interrupted in the middle by a large rectangle called the “Great Square.” (In the larger Ratzer Plan this will later be relabeled “Delancey’s Square.”)

Here’s where things get tricky. Only a few months—at most a year—had passed between the time Montresor finished his survey and when Ratzer would have been doing his own work. Had so much really changed in that time? 

There are at least three possible explanations. The first is that because Montresor was more concerned with topographical features than with roads, he didn’t get that section of the city right. This seems the least plausible theory, as he’d been specifically charged by Gen. Gage with mapping the northeastern part of the town.

The second possibility is that the roads had been built between the time Montresor and Ratzer completed their surveys. For example, the path of Division Street was agreed upon by Delancey and Rutgers on October 31, 1765, about six weeks before Montresor began his survey. It is certainly possible that when Montresor mapped that part of the city, Division Street didn’t yet exist and by the time Ratzer was there about a year later, it did.

However, that wouldn’t explain all the additions and changes in the Ratzen Plan, which leaves a plausible third choice: Some of the roads on the Ratzen Plan didn’t exist yet at all.

Ratzer may simply have been planning for the future. Cartography was a time-consuming and infrequent undertaking; if these were roads that the Delanceys planned to put in soon, there’s a chance Ratzer was hoping to make his map useful for future generations. (And to curry favor with the powerful Delancey family.) In fact, it’s possible some of the roads did exist as private streets and Montresor didn’t bother to include them, since they were not public thoroughfares.

That, however, doesn’t explain the missing “Great Square.” Since we have no evidence this square actually ever came to fruition, it seems more like it’s a planner’s rendering: the centerpiece of a Delancey family development that never happened, in part because the Delanceys ended up on the losing side of the American Revolution.

Similarly, there’s a spot on the map—near where the Alfred E. Smith houses now stand on the Lower East Side—where the defunct Rutgers Street runs straight through a swampy body of water. Montresor marks this as “overflow… constantly filling up in order to build on.” While Ratzer includes the road, he also shows the outlines of the swamp; as with Delancey’s Square, he’s definitely projecting into the future.

This isn’t that uncommon in mapmaking. After the publication of the Commissioners’ Plan of 1811—which laid out the rectilinear street grid of Manhattan up to 145th Street—New York maps immediately began to depict every straight street and avenue, even though many of them would not be graded, or even cut through, for years.

This doesn’t make these maps wrong, but it does mean that the farther Ratzer’s maps stray from densely populated areas, the more skeptical a modern reader needs to be when consulting them.